what is essay restricted and non restricted

TOPICS A. Fill-in-the-Blank Items B. Essay Questions C. Scoring Options

Assignments

Extended Response

Extended responses can be much longer and complex then short responses, but students should be encouraged to remain focused and organized. On the FCAT, students have 14 lines for each answer to an extended response item, and they are advised to allow approximately 10-15 minutes to complete each item. The FCAT extended responses are scored using a 4-point scoring rubric. A complete and correct answer is worth 4 points. A partial answer is worth 1, 2, or 3 points.

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i. Restrictive and Non-restrictive clauses

What are restrictive and non-restrictive clauses.

Consider these two sentences, both of which contain the same relative clause. Do you see the differences in their meanings?

All politicians who are crooks should go to jail.

All politicians , who are crooks, should go to jail.

The commas make a big difference. In the first sentence, we’re told that only those politicians who are crooks should go to jail.

In the second, we’re told parenthetically that all politicians are crooks, and they all should go to jail.

We’re comparing restrictive and non-restrictive relative clauses here. In the first sentence, the restrictive clause restricts the meaning of all politicians to include only those who are crooks. The non-restrictive clause in the second sentence informs us that all politicians are crooks.

The pair of commas in the second sentence (known as parenthetical commas ) make the enclosed information supplemental so that the relative clause does not modify or restrict the words all politicians .

Here are some more examples:

It’s fun to watch magicians who are clever .

It’s fun to watch magicians, who are clever .

The first sentence tells us that only some magicians (those who are clever) are fun. The second sentence gives us some supplementary information about all magicians.

Notice that the non-restrictive clauses could be enclosed in parentheses instead of commas.

In some sentences, the commas don’t seem to make much difference:

I dislike those baseball fans who are rude .

I dislike those baseball fans, who are rude .

In both cases, we’re speaking about a particular group of fans, although the first sentence seems to be about all rude fans; the second, about a particular group of rude fans.

LICENSE AND ATTRIBUTION

“Restrictive and Non-restrictive clauses” adapted from “Restrictive and non-restrictive clauses” of  Brehe’s Grammar Anatomy from  Steven Brehe, University of North Georgia , used according to creative commons  CC BY-SA 4.0 . Access for free at https://oer.galileo.usg.edu/english-textbooks/20/

UNM Core Writing OER Collection Copyright © 2023 by University of New Mexico is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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The ultimate essay test guide: achieve top grades with ease.

An essay test, a fundamental tool in academic assessment, measures a student's ability to express, argue, and structure their thoughts on a given subject through written words. This test format delves deeper into a student's critical thinking and writing skills unlike other conventional exam types.

What is an Essay Test?

An essay test is a type of assessment in which a student is prompted to respond to a question or a series of questions by writing an essay.

This form of test isn’t merely about checking a student’s recall or memorisation skills , but more about gauging their ability to comprehend a subject, synthesise information, and articulate their understanding effectively.

Types of Essay Tests

Essay tests can be broadly classified into two categories: Restricted Response and Extended Response .

• Restricted Response tests focus on limited aspects, requiring students to provide short, concise answers.
• Extended Response tests demand more comprehensive answers, allowing students to showcase their creativity and analytical skills.

Advantages and Limitations of an Essay Test

Essay tests offer numerous benefits but also have certain limitations. The advantages of an essay test are :

• They allow teachers to evaluate students’ abilities to organise, synthesise, and interpret information.
• They help in developing critical thinking and writing skills among students.
• They provide an opportunity for students to exhibit their knowledge and understanding of a subject in a broader context.

And the limitations of an essay test are :

• They are time-consuming to both take and grade.
• They are subject to scoring inconsistencies due to potential subjective bias.
• They may cause the students who struggle with written expression may face difficulties, and these tests may not accurately reflect the full spectrum of a student’s knowledge or understanding.

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Understanding the Structure of an Essay Test

Essay tests involve a defined structure to ensure organised, coherent, and comprehensive expression of thoughts. Adhering to a specific structure can enhance your ability to answer essay questions effectively .

The 7 Steps of an Essay

Writing an essay test typically involves seven steps :

• Understanding the question
• Brainstorming ideas
• Creating an outline
• Crafting a thesis statement
• Writing the essay body
• Formulating the conclusion
• Revising and editing for clarity and conciseness

The First Sentence in an Essay

The initial sentence of an essay, often termed a hook , plays a crucial role.

It aims to grab the reader’s attention and provoke interest in the essay topic. It should be engaging, and relevant, and set the tone for the rest of the essay .

The 5-Paragraph Essay Format

The 5-paragraph essay format is commonly used in essay tests, providing a clear and organised approach for students to articulate their ideas. In this format, the introduction and the conclusion include 1 paragraph, while the body of the essay includes 3 .

• Introduction : The introduction sets the stage, providing a brief overview of the topic and presenting the thesis statement – the central argument or point.
• Body : The body of the essay contains three paragraphs, each presenting a separate point that supports the thesis statement. Detailed explanations, evidence, and examples are included here to substantiate the points.
• Conclusion : The conclusion reiterates the thesis statement and summarises the main points. It provides a final perspective on the topic, drawing the essay to a close.

How to Prepare for an Essay Test?

Preparing for an essay test demands a structured approach to ensure thorough understanding and effective response. Here are some strategies to make this task more manageable:

#1 Familiarise Yourself with the Terminology Used

Knowledge of key terminologies is essential. Understand the meaning of directives such as “describe”, “compare”, “contrast”, or “analyse”. Each term guides you on what is expected in your essay and helps you to answer the question accurately.

To make it easier, you can take advantage of AI technologies. While preparing for your exam, use similar essay questions as prompts and see how AI understands and evaluates the questions. If you are unfamiliar with AI, you can check out The Best Chat GPT Prompts For Essay Writing .

#2 Review and Revise Past Essays

Take advantage of past essays or essay prompts to review and revise your writing . Analyse your strengths and areas for improvement, paying attention to grammar , structure , and clarity . This process helps you refine your writing skills and identify potential pitfalls to avoid in future tests.

#3 Practice Timed Writing

Simulate test conditions by practising timed writing . Set a specific time limit for each essay question and strive to complete it within that timeframe. This exercise builds your ability to think and write quickly , improving your efficiency during the actual test.

#4 Utilise Mnemonic Techniques

To aid in memorisation and recall of key concepts or arguments, employ mnemonic techniques . These memory aids, such as acronyms, visualisation, or association techniques, can help you retain important information and retrieve it during the test. Practice using mnemonics to reinforce your understanding of critical points.

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Strategies to Pass an Essay Test

Passing an essay test goes beyond understanding the topic; it also requires strategic planning and execution . Below are key strategies that can enhance your performance in an essay test.

• Read the exam paper thoroughly before diving into writing : read the entire exam paper thoroughly. Understand each question’s requirement and make a mental note of the points to be included in each response. This step will help in ensuring that no aspect of the question is overlooked.
• Answer in the First Sentence and Use the Language of the Question : Begin your essay by clearly stating your answer in the first sentence. Use the language of the question to show you are directly addressing the task. This approach ensures that your main argument is understood right from the start.
• Structure Your Essay : Adopt a logical essay structure , typically comprising an introduction, body, and conclusion. This helps in organising your thoughts, making your argument clearer, and enhancing the readability of your essay.
• Answer in Point Form When Running Out of Time : If time is running short, present your answer in point form. This approach allows you to cover more points quickly, ensuring you don’t leave any questions unanswered.
• Write as Legibly as Possible : Your writing should be clear and easy to read. Illegible handwriting could lead to misunderstandings and may negatively impact your grades.
• Number Your Answers : Ensure your answers are correctly numbered. This helps in aligning your responses with the respective questions, making it easier for the examiner to assess your work, and reducing chances of confusion or error
• Time Yourself on Each Question : Time management is crucial in an essay test. Allocate a specific amount of time to each question, taking into account the marks they carry. Ensure you leave ample time for revising and editing your responses. Practising this strategy can prevent last-minute rushes and result in a more polished essay.

About the Author Oğulcan Tezcan is a writer, translator, editor, and an accomplished engineer. Oğulcan is also a keen researcher and digital market analyst, with a particular interest in self-development, productivity, and human behaviour.

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Frequently Asked Questions About Essay Tests

How do you answer an essay question, when taking an essay test what is the first step, what type of test is an essay test, what is the first sentence in an essay, what are the six elements of an essay.

Good procedure is emphasized when: There is no product The procedure is orderly and directly observable Correct procedure is crucial to later success Analysis of procedural steps can aid in improving product Learning is at an early stage Good product is emphasized when: Different procedures result in an equally good product Procedure is not available for observation Procedural steps have been mastered Product has qualities that can be identified and judged Degrees of authenticity-- Note: More here than in your textbook

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Grammar: Relative, Restrictive, and Nonrestrictive Clauses

Relative clauses and relative pronouns, relative clause.

This is a clause that generally modifies a noun or a noun phrase and is often introduced by a relative pronoun ( which, that, who, whom, whose ). A relative clause connects ideas by using pronouns that relate to something previously mentioned and allows the writer to combine two independent clauses into one sentence. A relative clause is also known as an adjective clause. There are two types of relative clauses: restrictive and nonrestrictive .

Here are a few examples:

• The book that she read was important for her literature review. (restrictive)
• The participants who were interviewed volunteered to be part of the study. (restrictive)
• Walden University, which is entirely online , has main administrative offices in Baltimore and Minneapolis. (nonrestrictive)

Relative Pronouns

* In APA 7, per Section 4.19, use "who" or "whom" instead of "that" when referring to a human.

** Although both "which" and "that are grammatically correct in restrictive clauses, APA prefers "that" for restrictive clauses. See APA 7, Sections 4.19-4.21 for more information on this topic.

• Take this quiz on Grammar Diagnostic Quiz to test your understanding of relative pronouns.
• Use relative clauses to create more sentence variety .

Restrictive Clauses

Restrictive clause.

A restrictive clause restricts or defines the meaning of a noun or noun phrase and provides necessary information about the noun in the sentence. It is not separated from the rest of the sentence by commas. Restrictive clauses are more common in writing than nonrestrictive clauses. A restrictive clause is also sometimes referred to as an essential clause or phrase.

• The student who sits in the back of the room asks a lot of questions.
• The results that I obtained may invoke positive social change.
• The journalist whose story I read yesterday has won prizes for her work.

When the relative pronoun functions as the object of the sentence, it can (and usually is) omitted from the relative clause.

• The article that I requested did not arrive on time.
• The participants who I interviewed met me at the local library.

Nonrestrictive Clauses

Nonrestrictive clause.

A nonrestrictive clause adds additional information to a sentence. It is usually a proper noun or a common noun that refers to a unique person, thing, or event. It uses commas to show that the information is additional. The commas almost act like parentheses within the sentence. If the information between the commas is omitted, readers will still understand the overall meaning of the sentence. A nonrestrictive clause is also known as a nonessential clause or phrase.

• With the nonrestrictive clause omitted: I want to thank my father for all of his love and support.
• With the nonrestrictive clause omitted: The hypothesis was rejected.
• With the nonrestrictive clause omitted: I have found the article.

Although "that" is sometimes used in restrictive clauses, it is not allowed in nonrestrictive clauses.

• CORRECT: Minneapolis , which has a population of about 400,000, is the largest city in Minnesota.
• INCORRECT : Minneapolis , that has a population of about 400,000, is the largest city in Minnesota.  
• CORRECT: I had to fix my printer , which I bought less than a year ago.
• INCORRECT : I had to fix my printer, that I bought less than a year ago .

A relative pronoun cannot be deleted in a nonrestrictive clause.

• INCORRECT : Minneapolis , has a population of about 400,000, is the largest city in Minnesota.  
• INCORRECT : I had to fix my printer, I bought less than a year ago .

Reduced Relative Clauses

In academic writing, relative clauses are often reduced for a more concise style. This also creates more sentence variety . When reducing a relative clause, it is necessary to delete the relative pronoun and either delete or change the verb. Here are some examples:

• Gun control is a controversial issue that is about personal rights. ("be" + prepositional phrase)
• The steps that were followed were explained in the Methods section. (passive)
• Other researchers who are exploring the same topic have discovered similar solutions. (progressive verb tense)
• Participants who were available to meet in my office completed their interview there. ("be" + "-able " adjective)
• Some of the subjects lived in urban areas that had with high crime rates. ("have" as a main verb is replaced by "with")
• In this paper, I reviewed many research articles that addressed addressing the topic of gun control. (linking verbs or verbs describing facts can be changed to "–ing" clauses)
• The changes that are to be implemented with the new curriculum revisions are outlined in the handout. ("to" clauses)

Related Resources

Knowledge Check: Relative, Restrictive, and Nonrestrictive Clauses

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Restrictive and Non-restrictive Clauses

Which and that both introduce clauses (groups of words) that provide more information but are not grammatically necessary to the sentence.

• e.g., The daily special, which was poached salmon , cost a lot.
• e.g., The dish that the sous-chef prepared turned out to be better than the daily special.

Using Restrictive Clauses: That

Use  that  when the information in the clause is  necessary  to the meaning of the sentence. It’s called a restrictive clause because it  limits  or  affects the purpose  of the sentence.

• that weigh more than 23 kg  is necessary to the purpose of the sentence. If you removed this restrictive clause, it would imply that all suitcases must be checked, which isn’t what the author intends.
• that have caffeine  is also restrictive. If you take this part out, it suggests that all drinks make it hard to fall asleep.

Some writers will use  which  for a restrictive clause instead of  that . This is technically fine, but if you are having any confusion about the distinctions between restrictive and non-restrictive clauses, it is better to maintain a clear distinction between  that  and  which , for clarity’s sake.

Using Non-Restrictive Clauses: Which

Use  which  when the information in the clause is  not necessary  to the meaning of the sentence. It might be helpful or interesting, but if you took it out, the sentence would still make sense.

• If  which  was removed: e.g., The suitcase didn’t fit in the overhead bin.
• If  which  was removed: e.g., Coffee and tea are Canada’s favourite morning drinks.

Note that the non-restrictive which clause is set off by commas.

Use  that  without commas for a  restrictive  (necessary) clause.  That  is required more often than  which . Use  which  with commas for a  non-restrictive  (not necessary) clause.

Practice: Which vs. That

Write in  that  (for restrictive clauses) or  which  (for non-restrictive clauses).

• The spoon __________ fell on the floor needed to be washed.
• The book __________ she wanted was on the top shelf.
• They used Post-It notes __________ come in various colours to organize the pages.
• For the hike I need shoes __________ are sturdy.
• For the hike I need sturdy shoes __________ are expensive.
• The first skyscraper we saw __________ was the biggest one on that street had 67 floors.
• The only elevator __________ went all the way to the top was out of service.
• The cord __________ charges this computer is missing.
• He provided us with a whole box of samples __________ we didn’t really need so we could make a decision.

Which vs. That Practice Answers

Restrictive vs. Non-restrictive Clause: Use This Test to Know

• Updated on Nov 12, 2023

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Do you know why the second sentence takes a pair of commas but the first doesn’t, even though both look similar? Do you know why the third sentence, from a popular English daily, is incorrect without a comma?

The man who lives next door is an architect.

Mr. Lockwood, who lives next door , is an architect.

He said he is proud to call Bharti her sister who has stood by him through his life . Source

The first doesn’t take a pair of commas because the clause (underlined) is restrictive, but the second takes because the clause is non-restrictive. The third needs a comma after sister because the clause is non-restrictive. (Explanation of this later in the post.) Many, however, put commas in such cases whimsically, often where they feel like taking pause, distorting the meaning in the process.

In this post, we’ll learn the two types of relative clauses: restrictive and non-restrictive. The terms restrictive and non-restrictive are usually associated with relative clauses, but even words and phrases display these properties. Later in the post, we’ll touch upon such words and phrases as well.

Restrictive vs. non-restrictive clause

Let’s understand the difference between the two through an example.

Image source

Situation 1

You’ve to tell your friend that the person in white t-shirt is your neighbor. What if you say this to convey your message?

The person is my neighbor.

Will he understand who of the three is your neighbor? No. That’s because the above description fits all three.

But what if you say this to convey your message?

The person who is leaning is my neighbor. Or

The person who is wearing white striped t-shirt is my neighbor.

Note: In the examples, relative clause has been underlined and noun (or noun phrase) being described by the relative clause has been shown in magenta font .

By using the underlined clause, you’ve narrowed down the possibilities from three to one. In other words, you’ve restricted the possibilities from three to one. That’s what restrictive clauses do. They narrow down a general noun to more specific. Because narrowing down concerns only nouns, all the talk of restrictive and non-restrictive clauses holds only for relative clauses . (They’re the only clause that describe nouns.)

If you drop the relative clause in the above sentences, you get:

Without the relative clause, you don’t know who of the three is your neighbor. The sentences have clearly lost specificity or meaning.

Situation 2

Let’s take another situation from the same picture. Your friend knows that the person in white t-shirt is Tom, and you want to tell him that Tom is your neighbor. Will this be sufficient to convey the message?

Tom is my neighbor.

Yes. You don’t need to talk about his t-shirt or posture to identify him.

Identification is done and dusted. Now, if you want to give more information about Tom to your friend, you can write.

Tom , who helps me in math , is my neighbor.

Through the relative clause who helps me in math , you’ve added extra information in the same sentence, which otherwise would’ve taken another.

If you drop the relative clause in the above sentence, you get:

Even without the relative clause, you know who of the three is your neighbor. In other words, the sentence retains specificity or meaning.

The relative clause who helps me in math is a non-restrictive clause because it doesn’t restrict or narrow down the noun Tom . It merely adds extra information about the noun. Note that a non-restrictive clause comes with a pair of commas. There is only one comma though if the relative clause comes at the end of the sentence because period takes the place of second comma. (Comments that go with examples are in square brackets.)

Academics will be tough for me without Tom , who helps me in math . [ Comment : Only one comma]

In nutshell, a restrictive clause to narrows down or restricts or makes specific or identifies (they all mean the same thing) a general noun. It doesn’t take commas. A non-restrictive clause, in contrast, adds just extra information about a noun without restricting it. It takes commas (pair or one).

Restrictive clauses are also called essential clauses or defining clauses as without them the meaning changes. Non-restrictive clauses are also called non-essential clauses or non-defining clauses as they only add extra information to the sentence without affecting the meaning. Their role in determining the meaning of a sentence can be expressed through these metaphors:

A restrictive clause is heart and soul; without it, the sentence dies. A non-restrictive clause is arm and leg; without it, the sentence can survive.

In all the examples so far, we’ve looked at relative clauses starting with who . Other marker words that start a relative clause are whom , whose , which , that , when , where , and why . Of these, that has a peculiar characteristic.

That -clause is always restrictive

That relative clause is used only in restrictive sense. So, this would be incorrect.

The city’s airport , that was recently renovated , is seeing an all-time high traffic. [Incorrect]

Because the city has one airport, it is already identified, and we don’t need to narrow it down further. Therefore, the above clause is non-restrictive. For such non-restrictive clauses, we use which .

The city’s airport , which was recently renovated , is seeing an all-time high traffic. [Correct]

If the city has two airports, then we need to identify which of the two is seeing an all-time high traffic.

The city’s airport that was recently renovated is seeing an all-time high traffic. [Correct]

Which and that , which are both used to describe non-humans, confuse many. You can learn where to use which, with several examples, in this post on which vs. that .

Once identified, a noun doesn’t need restrictive clause again

If you’ve already identified a noun and if the same noun reappears later, you don’t need to identify it again.

Suppose you write this sentence when referring to the doctor the first time:

We thanked the doctor who performed heart surgery on my father . [Noun in magenta font and relative clause underlined]

Then if you refer to the same doctor later on in the same piece of writing, you don’t need to repeat the restrictive clause.

The doctor came to see us when he was in the town.

But you can drop in a non-restrictive clause whenever you need to add some extra information.

The doctor , who was visiting his daughter , came to see us when he was in the town.

Now, if you see the above sentence without what has come before, say, in an exercise, you may think why the relative clause is not restrictive. Therefore, to avoid confusion, in exercises you’ll often see common nouns carrying restrictive clauses. But if you see common nouns preceded by article the carrying non-restrictive clauses (like in the above sentence) in isolated sentences, it means that the noun has already been identified through the (that’s a function of the ).

Test to know which one (restrictive or non-restrictive) to use

A test to identify a restrictive clause from a non-restrictive clause is to drop the relative clause and see if the specificity of the noun changes. If it does, the clause is restrictive. If it doesn’t, the clause is non-restrictive. (This is nothing pathbreaking; it emanates from the basic definition of restrictive clauses narrowing down the noun and non-restrictive clauses doing nothing on this front.)

Let’s apply the test to few examples. Commas have been put in all four of them. If we identify any of them as restrictive, we’ll drop the commas.

The day , when most species will go extinct , will be a day of repentance and gloom.

The crow , that mimics a cormorant , is drowned.

The man , who started the rumour , has not been found.

If we drop the relative clauses, we get:

The day will be a day of repentance and gloom. [Which day are we talking about now? Black Friday. Christmas. Sunday. Specificity is clearly lost. So, the relative clause is restrictive.]

The crow is drowned. [Which crow? We meant a particular crow (the one that mimics a cormorant), but that specificity is lost without the relative clause. Hence, the clause is restrictive.]

The man has not been found. [Which man? We meant a particular man (the one who started the rumour), but that information is lost without the relative clause. Hence, the clause is restrictive.]

After learning which clause is restrictive and which is not, we can correct the commas.

The day when most species will go extinct will be a day of repentance and gloom. [Restrictive]

The crow that mimics a cormorant is drowned. [Restrictive]

The man who started the rumour has not been found. [Restrictive]

More resources on restrictive vs. non-restrictive:

• Exercises: Decide which (restrictive or non-restrictive clause) to use in a sentence

Examples of restrictive and non-restrictive clauses

In each of the next four examples, you’re given a base sentence to which you’ve to add a relative clause based on the information provided in each of the two scenarios. That’s how we write in essays and other pieces of real writing: we use background information to decide whether a sentence will take restrictive or non-restrictive clause.

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Base sentence: People of Fantasy Land are protesting against the new law requiring everyone to shave their heads.

Scenario 1 : People of Fantasy Land depend on mining, fishery, horticulture, and agriculture for their livelihood. All the people from mining industry are protesting. Nobody else is.

Answer 1 : People of Fantasy Land who depend on mining for their livelihood are protesting against the new law requiring everyone to shave their heads. [Noun in magenta font and relative clause underlined]

Since people follow different professions, we need to identify people among them who are protesting. Hence, a restrictive clause has been used.

Scenario 2 : People of Fantasy Land depend on mining alone for their livelihood, and all of them are protesting.

Answer 2 : People of Fantasy Land , who depend on mining for their livelihood , are protesting against the new law requiring everyone to shave their heads.

You don’t need to identify people who are protesting because all of them are engaged in mining. Here, this information is just extra. Alternatively, you can apply the test: drop the relative clause and see if any specificity is lost. It’s not.

How do I know that information is restrictive or non-restrictive unless I’m told?

I’ve received this question quite frequently from students.

When you’re writing real pieces, as opposed to answering isolated questions in exercises, you’ll know from the context whether the information is restrictive or not. A case in point is the example of Fantasy Land we just saw. Without knowing what people of Fantasy Land do for livelihood, we couldn’t have written the two sentences.

Often times though, like in case of proper nouns which don’t require further restriction, you won’t need details like we needed for Fantasy Land example.

In the next three examples as well, you’ll get background information to decide between restrictive and non-restrictive. Give it a try and then check the answer.

Base sentence: John’s brother came to meet me.

Scenario 1 : John has one brother, and he lives in Philadelphia.

Answer 1 : John’s brother , who lives in Philadelphia , came to meet me.

Because John has only one brother, we don’t need to identify him, and hence we require a non-restrictive clause. The information in relative clause is just extra.

Scenario 2 : John has two brothers: one lives in Philadelphia and the other in Chicago. The one living in Philadelphia came to meet me.

Answer 2 : John’s brother who lives in Philadelphia came to meet me.

Because John has two brothers, we need to identify who among the two came to meet me, and hence we require a restrictive clause.

Base sentence: Tom is walking with a limp today.

Scenario 1 : Tom’s leg came under a falling chair yesterday. There is only one student named Tom in the class.

Answer 1 : Tom , whose leg came under a falling chair yesterday , is walking with a limp today.

Scenario 2 : Tom’s leg came under a falling chair yesterday. There are two students named Tom in the class.

Answer 2 : Tom whose leg came under a falling chair yesterday is walking with a limp today.

Base sentence: The government will honor the sportspersons.

Scenario 1 : All the sportspersons won a medal, and they’ll be honored.

Answer 1 : The government will honor the sportspersons , who won a medal .

We don’t need to identify the sportspersons because all of them won a medal and all of them will be honored.

Scenario 2 : Few sportspersons won a medal, and only they’ll be honored.

Answer 2 : The government will honor the sportspersons who won a medal .

We need to identify the sportspersons because not everyone won the medal.

More examples

He said he is proud to call Bharti her sister, who has stood by him through his life . Source [Non-restrictive. This is the example we saw at the beginning of the post. If the relative clause was restrictive, it would mean that he has more than one sister and that they fall in two categories: those who have stood by him though his life and those who haven’t.]

The old man who got out of a swanky car minutes ago walked straight into the meeting room. [Restrictive. You can apply the test to this and other examples.]

Because of few issues with the test, people who were told they tested negative are being recalled. [Restrictive]

Anyone who makes silly mistakes in the exercise can retake it. [Restrictive]

The doctor whom my father visited for several years now lives in Singapore. [Restrictive]

The lawyer whose car was stolen last week came to see my dad today. [Restrictive]

Friday , which happens to be my birthday , is the only day when I am available to meet . [Non-restrictive and restrictive]

Tom surprisingly got along well with Mac , whose quirky personality seemed to fascinate him . [Non-restrictive]

In life’s journey don’t be obsessed with the final reward , which may come after many months or years or may not come at all , but enjoy little achievements and experiences every day. [Non-restrictive]

The solution is alkaline , which means it has a pH of more than 7 . [Non-restrictive]

Albert Einstein proposed theory of relativity , which states that gravity affects the fabric of space-time . [Non-restrictive]

To increase human longevity, scientists had to first unbelieve the existing dogma that every living being’s lifespan is predetermined by God . [Restrictive. There are so many dogmas, so we need to specify through a restrictive clause.]

After Roger Bannister’s record-breaking run, self-belief among athletes that a mile can be run under four minutes changed. [Restrictive]

Restrictive vs. non-restrictive words and phrases

As we discussed earlier, restrictive and non-restrictive terms come into play when a word, phrase, or a clause describes (or modifies) a noun. Now, is relative clause the only entity that modifies a noun? No.

Adjectives, appositive phrases, prepositional phrases, participial phrases, and infinitive phrases too can modify nouns in some situations, and hence they too can be restrictive or non-restrictive. (Appositive phrase is not exactly a modifier. It’s a noun phrase that merely restates a noun in different words.)

Here are few examples of each of these. To get most out of these examples, note how restrictive word or phrase narrows down the noun it modifies and how non-restrictive word or phrase merely adds extra information. You can in fact apply the test we covered earlier by dropping the modifying word or phrase (underlined).

1. Adjective

The blue dress stands out. [Restrictive. The adjective restricts the dresses to only blue dresses.]

The dying man wrote his will. [Restrictive]

Mary had a busy schedule . [Restrictive]

2. Appositive

John F. Kennedy , U.S. President , set the goal of landing a human on moon. [Non-restrictive. If we drop the appositive phrase, the identification isn’t lost. Remember, a proper noun always takes a non-restrictive modifier.]

U.S. President John F. Kennedy set the goal of landing a human on moon. [Restrictive. If we drop the appositive phrase, identification is lost. We would not know which U.S. President set the goal.]

Megalodon , the most feared predator ever in the ocean , went extinct nearly two million years ago. [Non-restrictive]

3. Prepositional phrase

My trip to Chicago was cancelled at the last minute. [Restrictive]

The sprinter in the yellow body suit is the favorite to win the race. [Restrictive]

My brother , in blue shirt , works in Microsoft. [Non-restrictive. Because my brother is already identified, we don’t need restrictive phrase. If I have two brothers and both are standing together, then I need a restrictive prepositional phrase to identify: My brother in blue shirt works in Microsoft.]

Do you know why the third sentence , from a popular English daily , is incorrect without a comma? [Non-restrictive. This is a sentence in the opening paragraph of this post. If the phrase was restrictive, it would mean that the sentence being referred to is the third sentence from the article in the English daily, which is not the case.]

4. Participial phrase

The sprinter waving at the audience is the favorite to win the race. [Restrictive]

Tom , knowing that he is unlikely to win the race , was relaxed. [Non-restrictive. Remember, a proper noun is already identified and hence takes a non-restrictive modifier.]

The damage to the car caused by the accident was significant. [Restrictive. Note that to the car is a restrictive prepositional phrase.]

5. Infinitive phrase

My dream to participate in the event was shattered because of the injury. [Restrictive]

Your decision to miss the trials has not been taken well. [Restrictive]

His attempt to pacify his supporters failed. [Restrictive]

If a decision such as picking college, college major, or career comes from own choice, we don’t feel bad if it turns out to be bad. [Restrictive]

Many start-ups are building products and services on innovations of the past , such as blockchain, UPI, and GPT 3 . [Non-restrictive]

How understanding restrictive vs. non-restrictive helps your writing?

You should learn the difference between restrictive and non-restrictive to write correct English. Period. Let’s see some common errors and see how they change the meaning or confuse readers.

The man , who lives next door , is an architect.

Mr. Lockwood who lives next door is an architect.

The man who lives next door , is an architect.

The non-restrictive clause in the first sentence would imply that we already know who the man is. If you’ve already introduced this person in earlier sentences, this is fine (we saw this topic earlier in the post). But if not, then the readers will scratch their heads, trying to figure out who this man is.

The incorrect use of restrictive clause in the second sentence would imply that there are more than one Mr. Lockwood, and we’re trying to identify one of them.

The incorrect use of just one comma leaves readers hanging because they’re expecting two or none. BTW, this is a common error, especially when the relative clause gets long. Example:

Anyone who takes an exercise and later on realizes that they made a silly mistake or didn’t grasp the question correctly can retake it.

It’s a restrictive clause and the sentence wouldn’t take any comma, but many get restless while writing such long restrictive clause and put an unwarranted comma to take a pause, but commas aren’t governed by pause.

Anil is the person behind content on this website, which is visited by 3,000,000+ learners every year. He writes on most aspects of English Language Skills. More about him here:

What Are Restrictive and Nonrestrictive Clauses? Definitions and Examples

Do you want to learn more about restrictive and nonrestrictive clauses? Then you've come to the right place. This article will teach you what you need to know about them in order to use them correctly in your writing.

• A restrictive clause is a clause that's essential to the meaning of the sentence.
• A nonrestrictive clause can easily be removed without affecting the meaning. 

This guide is part of our free online Grammar Book .

What Are Clauses, and What Does Restrictive or Nonrestrictive Mean?

Before we get started, let's talk about the meaning of the word 'clause.' What exactly are clauses ? Well, quite simply, a clause is a group of words containing a subject and predicate .

Here's an example of a clause:

I've never been here before .

The subject is 'I,' and the predicate is 'been here before' (it's the verb and any other word that relates to the verb). It's easy to tell a clause apart from a phrase because a phrase doesn't have a subject, a verb, or both, so they don't convey a complete thought.

Here's an example of a phrase:

the best thing ever. 

Though clauses always convey a complete thought, sometimes they can stand alone (independent clauses), and other times they can't (dependent clauses). To learn more about clauses check out this article .

What we're here to learn about today is the two kinds of clauses: restrictive and nonrestrictive. So here goes.

What Are Restrictive Clauses?

Both restrictive and nonrestrictive clauses provide information about the sentence's subject. The difference between the two is that restrictive clauses offer information that's important to the sentence's meaning.

That's why restrictive clauses are also often called essential clauses, which I think is a great way to remember what they actually are: essential. This means that if you removed these clauses from the sentence, you would lose some vital information.

Let's take a look at an example:

The book that you have in your hands is very interesting. 

Here , the clause 'that you have in your hands' is restrictive because it provides an essential piece of information. It tells us that it's a specific book that's very interesting. It's not just any book; it's the one you have in your hands. If we removed that clause, we'd get the following:

The book is very interesting. 

Not the same thing at all, is it? And while this sentence is perfectly satisfactory, grammatically. It just doesn't convey the same meaning.

Another great way to remember what restrictive clauses do is to think of the meaning of the word 'restrictive.' Because what do restrictive clauses do? By definition, they restrict. They take something general, and they narrow it down. They limit. They help a sentence specify what they are referring to.

Here are some more examples with the restrictive clause underlined:

The person who was sitting next to me wouldn't stop snoring.  Children whose homework isn't completed should head to detention. The job that I just applied for is based in New York. Please can the people whose name I call out come and stand to my left. Airplanes that were used in the war can be found in the local museum.

You might notice that restrictive clauses often start with relative pronouns like 'who,' 'that,' or 'whose.' But as we'll see later, nonrestrictive clauses can also begin with relative pronouns. Other times, the relative pronouns might be implied but not explicitly stated.

Here are some examples where I've inserted the relative pronoun in brackets where it could be:

The house (that) I'm thinking of buying is in the city center . The person (who) this car belongs to is a VIP. Let me tell you about all the places (that) you must visit in New York.  The teachers (who are) helping with the annual bakesale get an extra day off.  The mentor ( whom ) inspired me the most got a special mention in my book.

What Are Nonrestrictive Clauses?

Now we've covered what restrictive clauses are; we can move on to nonrestrictive clauses. What do you think they are? You'd be right if you guessed that nonrestrictive clauses were the opposite of restrictive clauses.

Nonrestrictive clauses—also known as non-essential clauses—provide information that isn't crucial to the sentence's meaning. The info a nonrestrictive sentence provides is good to have, as it gives us additional details, but it wouldn't alter the sentence's meaning if it were removed.

Here's an example:

Red, my favorite color , is the color of passion. 

It isn't massively important for the reader to know that red is the reader's favorite color; it's just an added bonus. The most important message this sentence is trying to convey is that red is the color of passion. That's why removing that information about it being the writer's favorite color wouldn't detract from the meaning. And that's why it's a nonrestrictive clause.

Red is the color of passion. 

As you can see , after removing the nonrestrictive clause, the sentence is still grammatically correct and tells us what we need to know. Let's take a look at some more examples with the nonrestrictive clause underlined:

The man, whom I'd never seen before , was said to be very kind. Sharks, which many people are afraid of , get a bad rap. The vet, who was a patient and loving woman , gave me some great advice. My new company, which I'll be launching later this year , will be a huge success. That candle, which was gifted to me by my mom , reminds me of my childhood.

As you may have noticed, and as I mentioned earlier, relative pronouns often introduce nonrestrictive clauses. But this isn't always the case, and furthermore, sometimes, the pronoun will be implied. Let's have a look at some more examples where the relative pronoun, if relevant, is added in brackets where it should be:

My daughter, (who was) born in the state of Arizona, recently moved to the Big Apple for a new job. His laptop,  (which is) over ten years old, is falling apart. The village's doctor, (who was) a man who enjoyed his comforts, passed away last year. 

You may also notice that nonrestrictive clauses are set off by commas. Basically, the bit in between the commas is the bit that can be removed.

Let's try it with some of our previous examples:

His laptop is falling apart. The village's doctor passed away last year. 

As you can see, these sentences are still correct, make sense , and retain the primary meaning. That's the true telltale that the clauses we removed were nonrestrictive.

You can also offset nonrestrictive clauses with other punctuation if you wish. Some other appropriate types of punctuation are em dashes and parentheses .

Concluding Thoughts

That concludes this article on restrictive and nonrestrictive clauses. I hope you found it helpful.

Let's summarize what we've learned:

• A clause contains a subject and a predicate.
• Restrictive clauses provide essential information and cannot be removed from the sentence.
• Nonrestrictive clauses can be removed without affecting the sentence's meaning.
• Both types of clauses provide information about the sentence's subject.
• Nonrestrictive clauses should be offset from the rest of the sentence by commas or other appropriate punctuation. 

If you enjoyed this article, then you might like our Grammar Book , a free online database of grammar articles just like this one. Check it out!

Learn More:

• Noun Clauses: What Are Noun Clauses? Definition and Examples
• What Are Subject-Verb Agreements? Definitions and Examples
• Transition Words: What Are Transition Words? Definitions and Examples
• Countable Nouns: What Are Countable Nouns? Definitions and Examples
• Auxiliary Verbs: What Are Auxiliary Verbs? Definitions and Examples
• What Are Comparative and Superlative Adjectives? Definitions and Examples
• Regular vs Irregular Verbs: Definitions, Differences, Examples
• Clauses: What is a Clause?
• Simple Sentence: What Is a Simple Sentence? Definition and Examples
• 'Bear With Me' or 'Bare With Me'? (Definitions and Examples)
• ‘XXX' and 'XOXO’: Meaning, Definitions, and Examples
• 'That' vs 'Which': Definitions, Differences, and When to Use
• Writing Numbers: How to Write Numbers Correctly (Examples)
• Abstract Nouns: What Are Abstract Nouns? Definition and Examples
• Antecedents: What are Antecedents? Definition and Examples

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Nonrestrictive Elements: Definition and Examples

• An Introduction to Punctuation
• Ph.D., Rhetoric and English, University of Georgia
• M.A., Modern English and American Literature, University of Leicester
• B.A., English, State University of New York

In contrast to a  restrictive element , a nonrestrictive element is word, phrase, or dependent clause that provides added (though not essential) information to a sentence but does not limit (or restrict) the element it modifies.

It is also sometimes known as a non-defining, supplementary, nonlimiting, or nonessential modifier. A nonrestrictive element is usually set off with commas .

Examples and Observations

• Judy Green and Jeanne LaDuke "Audrey Wishard McMillan, who was born in India , was the daughter of Americans living abroad and was educated in a school for children of American missionaries."  — " Pioneering Women in American Mathematics." American Mathematical Society, 2009
• Douglas Adams "Human beings, who are almost unique in having the ability to learn from the experience of others , are also remarkable for their apparent disinclination to do so."  — " Last Chance to See." Harmony Books, 1991
• Madonna King "As the one lane became two, Ben moved from the left lane towards the right one, and the couple, who first met at high school , were chatting easily. And then Ben, who was sitting on the speed limit of 60 kilometres an hour , started to grow a bit edgy. He told Renee about the idiot he could see in his rear-vision mirror who was driving too fast."  — " Catalyst: The Power of the Media and the Public to Make Change." University of Queensland Press, 2005
• Everett M. Rogers "Many other technologies resulted from serendipity. A well-known example is penicillin, which was discovered by accident by Sir Alexander Fleming .  — " Diffusion of Innovations," 5th ed. Free Press, 2003
• David Markson "The book was a life of Brahms, which had been standing askew on one of the shelves here and which the dampness had left permanently misshapen ."  — " Wittgenstein's Mistress." Dalkey Archive Press, 1988
• Elizabeth Kolbert "Samsø, which is roughly the size of Nantucket , sits in what’s known as the Kattegat, an arm of the North Sea . The island is bulgy in the south and narrows to a bladelike point in the north, so that on a map it looks a bit like a woman’s torso and a bit like a meat cleaver." –"The Island in the Wind." The New Yorker, July 7, 2008
• Patricia Cohen "Health sciences, computer science, engineering and business— fields that have tended to attract a somewhat greater proportion of moderates and conservatives— have grown in importance and size compared with the more liberal social sciences and humanities, where many of the bitterest fights over curriculum and theory occurred ."  —  "The ’60s Begin to Fade as Liberal Professors Retire." The New York Times, July 4, 2008

Relative Clauses

• Elly van Gelderen ​ " Clauses that modify nouns, such as the one in (4), are referred to as relative clauses (RC) because the noun they modify ( stories in this case) plays a role (has a function) in the RC. The RC is related to the noun by means of which. (4) The stories [which he repeats often] are boring. The element that connects the noun and the clause, i.e. which in (4), is called a relative pronoun. In (4), the relative pronoun functions as the direct object of repeat. "RCs are usually divided into restrictive as in (4) and non-restrictive , as in (5) and (6): (5) Hillary Clinton, who just returned from a trip to Cuba, intends to write a book. (6) Queen Elizabeth the first, who was born in 1533, was the last sovereign of the house of Tudor. The reason we discuss the difference between restrictive and non-restrictive clauses is that the use of one over the other has grammatical (and possibly other) consequences."
• Martha Kolln "Not all participial phrases are restrictive. Sometimes the referent of the noun is already identified, so a modifier isn't necessary. In such cases, the purpose of the modifier is simply to comment on or to add information about the noun, not to define it. Such modifiers are called nonrestrictive modifiers. My mother, sitting by the window, is talking to herself. In this sentence the noun phrase my mother is already specific; it has only one possible referent. Sitting by the window simply adds a detail of information."

Punctuation

• Anne Lobeck and Kristin Denham "Nonrestrictive relative clauses... do not restrict the reference of the noun. They are also usually set off by commas in writing, and you can also usually detect 'comma intonation' in a speaker's voice. Restrictive The paint which Mary bought at the hardware store was bright red. Nonrestrictive The paint, which Mary bought at the hardware store , was bright red. The restrictive relative clause which Mary bought at the hardware store , limits which paint we're referring to, namely to, paint which Mary bought at the hardware store. The nonrestrictive relative clause, on the other hand, does not restrict the reference of the noun paint ; it is not information that distinguishes the paint from other paint. That Mary bought this paint at the hardware store is simply incidental information."

Elements: That and Which

• ​John McPhee "Ordinarily, the conjunction 'that' would introduce a restrictive clause. Nonrestrictive: This is a baseball, which is spherical and white. Restrictive: This is the baseball that Babe Ruth hit out of the park after pointing at the fence in Chicago. The first ball is unspecific, and that sentence requires a comma if the writer wishes to digress into its shape and color. The second ball is very specific, and the sentence repels commas."
• Van Gelderen, Elly. "An Introduction to the Grammar of English." Rev. ed., John Benjamins, 2010, Amsterdam.
• Kolln, Marth. "Rhetorical Grammar: Grammatical Choices, Rhetorical Effects," 3rd ed., Allyn and Bacon, 1999, Boston.
• Lobeck, Anne and Denham, Kristin. "Navigating English Grammar: A Guide to Analyzing Real Language." Wiley-Blackwell, 2014, Hoboken, N.J.
• McPhee, John. "The Writing Life: Draft No. 4." The New Yorker, April 29, 2013.
• Nonrestrictive Relative Clause
• Restrictive Relative Clause
• What Are Restrictive and Nonrestrictive Adjective Clauses
• Relative Adverbs in English
• Relative Clause Definition and Examples in English
• How to Build Sentences with Appositives
• What Is an Adjective Clause?
• Subordination With Adjective Clauses
• How to Use a Relative Clause
• Appositive Adjective
• summative modifier (grammar)
• How to Recognize and Use Clauses in English Grammar
• What Is a Modifier in Grammar?
• Contact Clauses in English
• Dependent Clause: Definition and Examples
• The Comma in Punctuation

NLRB to Defend Severance Agreement Decision at Sixth Circuit

By Parker Purifoy

A Michigan hospital will urge a federal appeals court to overturn a labor board ruling that restricted employers’ ability to use broad non-disparagement and non-disclosure provisions in employee severance agreements.

During oral argument in the US Court of Appeals for the Sixth Circuit Tuesday, McLaren Macomb—a teaching hospital in Mount Clemens, Mich.—is expected to argue that the National Labor Relations Board went beyond the scope of its authority when it struck down a Trump-era legal doctrine.

The board, which is simultaneously seeking court enforcement of its February 2023 decision , argues that the new standard protects workers’ rights to talk ...

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• Published: 29 April 2024

Predictive value of lactate dehydrogenase for Mycoplasma pneumoniae necrotizing pneumonia in children based on decision curve analysis and dose–response analysis

• Ren Yanhong 1 , 2   na1 ,
• Zhao Shuai 1 , 2   na1 ,
• Chen Dan 1 , 2 &
• Sun Xiaomin 1 , 2  

Scientific Reports volume  14 , Article number:  9803 ( 2024 ) Cite this article

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Mycoplasma pneumoniae necrotizing pneumonia (MPNP) has a long and severe disease course, which seriously threatens to jeopardize patients' lives and health. Early prediction is essential for good recovery and prognosis. In the present study, we retrospect 128 children with MPNP and 118 children with Mycoplasma pneumonia e pneumonia combined with pulmonary consolidation to explore the predictive value of lactate dehydrogenase (LDH) in children with MPNP by propensity score matching method, multiple logistic regression analysis, dose–response analysis and decision curve analysis. The WBC count, PLT count and percentage of neutrophils were significantly higher in necrosis group than consolidation group. The serum CRP, PCT, ESR, D-D, FIB, ALT, LDH, IgG and IgM were significantly higher in necrosis group. Compared to consolidation group, necrosis group is more severe in chest pain and dyspnea. Multivariate logistic regression analysis showed that duration of LDH levels, high fever, d -dimer, and fibrinogen were independent predictive factors for the incidence of MPNP. Restricted cubic spline analysis showed that a non-linear dose–response relationship between the continuous changes of LDH level and the incidence of MPNP. Decision curve analysis revealed that LDH had an important clinical value in predicting MPNP. This study provides a potential serologic indicator for early diagnosis of MPNP.

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Introduction.

Mycoplasma pneumoniae (MP) is a common pathogen that causes lower respiratory tract infections in children 1 and cause up to 20 to 40% of community-acquired pneumonia 2 . In China, Mycoplasma pneumoniae pneumonia (MPP) accounts for about 32.4% of community-acquired pneumonia in children 3 . Necrotizing pneumonia (NP) is a disease characterized by inflammation and necrosis of lung tissue caused by pulmonary infection. In the early stages, the disease presents as consolidation of the lung, followed by liquefaction necrosis and the formation of multiple cystic or thin-walled cavities 4 . NP is usually caused by Streptococcus pneumoniae and Staphylococcus aureus 4 . In recent years, the incidence of Mycoplasma pneumoniae necrotizing pneumonia (MPNP), a specific form of necrotizing pneumonia caused by Mycoplasma pneumoniae , has been found to be on the rise, and MP is expected to become the main pathogen of NP 5 , 6 , 7 . MPNP is a severe complication of MPP , characterized by a prolonged and severe course of illness 2 , 6 . Patients may develop complications such as pneumothorax and bronchopleural fistula, which can even be life-threatening 8 . In view of the severity of NP and heavy burden of hospitalization, early prediction is essential for good recovery and prognosis.

Currently, contrast-enhanced chest CT is still the most sensitive modality for the diagnosis of NP 9 . Pulmonary consolidations present several weeks before cavities appear. It has been shown that the CT value of pulmonary lesions in NP was lower than that in non-NP and may help predict NP early 2 . However, in order to minimize radiation hazards, it is necessary to find new serological markers. Dan and colleagues investigated the potential of the peripheral blood neutrophil-to-lymphocyte ratio (NLR) to predict outcomes in patients with MPP. They found that Patients with a high NLR were more likely to develop NP and refractory Mycoplasma pneumoniae pneumonia (RMPP) and require intensive care, and had longer total fever duration, longer hospital stays, and higher hospitalization expenses than those with a low NLR 1 . The results suggested that the NLR can serve as a predictor of poor prognosis in patients with MPP and can predict the occurrence of NP, RMPP, and other poor outcomes. Xue’s 7 research revealed that age, fever days, alanine transaminase (ALT), immunoglobulin M (IgM), complement C3, fibrinogen, dyspnea, and needing fiberoptic bronchoscopic alveolar lavage were independent risk factors for MPNP in children. Xue’s study also reported that serum lactate dehydrogenase (LDH) was higher than in the MPNP group were higher than those in the control group. Consistent with this result, Zhou’s et.al 2 reported that MPP patients with NP might be easier to suffer from persistent fever, pulmonary consolidation, result in elevated LDH, WBC, CRP and disorder of cytokines. Paying close attention to these indicators may help in the early diagnosis of children suspected of MPNP.

Lactate dehydrogenase (LDH) is an enzyme involved in the anaerobic metabolism of the body, and it is widely distributed in red blood cells, myocardium, renal cells, hepatocytes and lung tissues. LDH is a pan-necrosis marker that can be released by cells undergoing primary or secondary necrosis 10 . When lung tissue is damaged, the permeability of cell membranes increases, resulting in the release of LDH into the bloodstream, which cause an increase of serum LDH 11 . During pneumonia, the inflammation and hypoxia in the lungs lead to increased serum LDH. In pediatric NP, the level of pleural fluid LDH is often > 1000 U/L and serum LDH is ≥ 353.5 U/L 4 . Paying attention to the high level of LDH may be useful in informing clinicians of the possibility of ongoing necrosis of the pulmonary parenchyma 12 . Therefore, investigation of the predictive value of LDH in MPNP in children and establishing an early prediction model for MPNP in children is crucial for diagnosis, treatment, and improving prognosis.

In this study, we explored the association strength between LDH continuous changes and MPNP using restricted cubic splines and evaluated the predictive value of developing MPNP in children with pneumonia caused by Mycoplasma pneumoniae and lung consolidation using decision curve analysis.

General situation of two sets of related clinical factors

The clinical information of enrolled patients was shown in Table 1 . There was no significant difference in age, gender, high fever, and wheezing between the consolidation group and the necrosis group ( P  > 0.05). While, the WBC count, PLT count, NE% were higher in necrosis group than consolidation group. Corresponding to this, the serum LDH, CRP, PCT, ESR, D-D, FIB, ALT, IgG, and IgM levels in necrosis group were significantly higher than consolidation group, as well as the differences in chest pain and dyspnea between the two groups were statistically significant ( P  < 0.05).

Correlation analysis of clinical factors and MPNP incidence

The relationship between LDH values and the incidence of MPNP was calculated using LDH values as the horizontal axis and the probability of MPNP incidence as the vertical axis. The probability curve of LDH and MPNP incidence was plotted through single factor logistic regression, as shown in Fig.  1 . The result shows that LDH values had corresponding MPNP incidence. Multivariate logistic regression analysis was then performed by univariate analysis with statistically significant indicators listed as independent variables and the incidence of MPNP as the dependent variable. The results suggested that LDH, PLT, DD and IgG were independent predictors of MPNP incidence (all P  < 0.05), as shown in Table 2 .

Correlation analysis of LDH and MPNP incidence.

The predictive value of LDH for the incidence of MPNP

Then, we evaluated the predictive value of LDH for the incidence of MPNP. Taking LDH as the predictor, sensitivity as the ordinate and 1-specificity as the abscissa, the calculated area under the ROC curve 0.827 (95% CI: 0.774–0.880). When LDH is 393.0 U/L, the Jordan index is the highest, at 0.545. Therefore, setting LDH at 393.0 U/L as the optimal cutoff value, the sensitivity and specificity of prediction are 68.3% and 86.2%, respectively. When LDH > 393.0 U/L, as LDH increases, the risk of developing necrotizing pneumonia in children with Mycoplasma pneumoniae pneumonia and pulmonary consolidation significantly increases (Fig.  2 ).

ROC curve of LDH predicting MPNP incidence.

The dose–response analysis of the correlation between LDH and MPNP

The dose–response analysis of the correlation strength between LDH and MPNP was conducted using the optimal cutoff value of LDH at 393.0 U/L as the reference value. The restricted cubic spline method combining spline function and logistic regression was used to analyze the dose–response relationship between LDH and MPNP. The horizontal axis represents the continuous change of LDH, the vertical axis represents the corresponding predicted value (OR), and the shaded part represents 95% CI. Our study suggested that the correlation between continuous changes in LDH and MPNP showed a non-linear dose–response relationship (P < 0.01). The results showed a significantly positive correlation between LDH and the incidence of MPNP. With the LDH increasing especially when LDH > 393.0 UL the risk of MPNP disease significantly increased (Fig.  3 ).

The dose–response relationship between LDH and MPNP based on the restricted cubic spline model. The continuous change of LDH and the intensity of the correlation between MPNP exhibited a nonlinear dose–response relationship.

Decision curve analysis (DCA) of LDH and MPNP

The sensitivity, specificity, and area under the ROC curve reflects the diagnostic accuracy of the model. However, they lack consideration of the clinical effectiveness of a particular model. The advantage of decision curve analysis lies in its integration of patient or decision-maker preferences into the analysis. In this study, the DCA curve was draw with the net profit rate as the vertical axis and the high-risk threshold as the horizontal axis (Fig.  4 ). The high-risk threshold is set to (0, 1). When the high-risk threshold is > 0 (the incidence risk value corresponding to LDH value can be obtained from Fig.  1 ), the net benefit rate is greater than 0 (actually > 0.25), which is clinically significant. (Fig.  4 ).

Decision curve analysis of LDH.

Mycoplasma pneumoniae is an important pathogen of children's community acquired pneumonia. The incidence rate of MPP is increasing, with worldwide incidence of 8·61% from 2017 to 2020 13 . Although nonpharmacologic interventions targeting COVID-19 greatly reduced Mycoplasma pneumococcal infection between 2020 and 2023 14 , however, if Mycoplasma pneumococcal infections resurge, it could affect a world population that has not been exposed to Mycoplasma pneumoniae in the past 3 years 15 and result in an increase in rare severe diseases and extrapulmonary manifestations 16 . Early prediction is essential for good recovery and prognosis of Mycoplasma pneumoniae and is an effective means of dealing effectively with Mycoplasma pneumoniae infection.

LDH is present in the cytoplasm of cells. When cells are infected, cytoplasmic membrane permeability increases and LDH is released into the bloodstream. Therefore, LDH can be used as a serologic marker of disease. Pulmonary complications in children with severe M. pneumoniae pneumonia are associated with higher levels of LDH and LDH to albumin ratio 8 , 17 , 18 . The level of LDH in children with MPNP [428.50 (319.25–598.25)] were higher than children with MPP [351.00 (297.25–470.23)] 7 . It may because MPP patients with NP might be easier to suffer from persistent fever, pulmonary consolidation, result in elevated WBC, CRP, LDH and disorder of cytokines 2 .

However, the cutoff of LDH values were inconsistent across reports. Chen’s study revealed that the level of pleural fluid LDH is often > 1000 U/L in NP among children, while serum LDH is ≥ 353.5 U/L 9 . Thus, serum LDH ≥ 353.5 U/L and/or pleural fluid LDH > 1000 U/L), NP would be more suspicious. Zhang’s study revealed that LDH in 428.50 (319.25–598.25) U/L in MPNP and 351.00 (297.25–470.23) in control group 7 . Luo and colleagues’ study reported that the LDH level in serum of necrotizing pneumonia group is 336.00 [274.00, 412.00] U/L and 316.00 [271.75, 365.50] U/L in non-necrotizing pneumonia group 19 . While Zhou’s study 2 and Yang’s study 20 reported that LDH was 646 (393–971) U/L and 805.0 (423.7–1029.5) U/L in MPNP group, and 494 (388–693) and 414.0 (299.9–540.6) in non-MPNP. These may be closely related to sample size, sample population, and age.

This study indicated that LDH was an independent factor in the incidence of MPNP in children. The area under the ROC curve was 0.827 indicating that the accuracy of LDH in predicting MPNP in children was consistent with previous research 21 . The cutoff value of LDH in this study was 393.0 U/L, and the sensitivity and specificity of prediction were 68.3% and 86.2%, respectively. Previous study 21 has calculated the correlation strength between LDH and MPNP in traditional logistic models regardless of the trajectory of changes in LDH continuity and MPNP correlation strength. Artificially segmenting LDH for research may not only result in loss of information but may also result in inaccurate results. Our study matched the baseline data of children by the propensity score matching method which avoided bias in baseline data. We also found that LDH was an independent predictive factor for the incidence of MPNP through multiple logistic regression analysis. Dose response analysis was used to observe the prediction of different changes in LDH on the risk of MPNP incidence, and decision curve analysis was used to evaluate its predictive value. However, the present study still has some limitations, such as the lack of external controls, which prevents the validation of the scalability of the established models. Therefore, future prospective experiments with the currently established indicators are necessary to understand the stability of the model.

In summary, LDH is an independent predictor of the incidence of MPNP in children and has important value in predicting MPNP. It has a significant nonlinear dose–response relationship with MPNP incidence. The risk of MPNP incidence significantly increases with the increasing LDH especially when LDH > 393.0 U/L.

Study population.

This is a retrospective study and focuses on 4899 children with MPP who were hospitalized at the Affiliated Children's Hospital of Zhengzhou University from January 2019 to June 2022. All selected children must meet the following criteria: ① 1–14 years old; ② the diagnostic of MPP was according to Zhu Futang Practical Pediatrics criteria, which with fever and cough as the main clinical manifestations, chest X-ray or chest CT indicating pneumonia, single MP antibody titer ≥ 1:160, MP antibody titer increased or decreased by 4 times or more in the recovery and acute stages, single test positive for MP-IgM and positive for MP DNA in nasopharyngeal swab or alveolar lavage fluid; ③ Duration of disease at admission: 1–3 weeks. Within 24 h of admission, routine blood tests, percentage of neutrophil, C-reactive protein (CRP), lactate dehydrogenase (LDH), d -dimer, liver function and other related tests are performed. Children with previous history of bronchial asthma, recurrent respiratory infections, primary or secondary immune dysfunction, congenital heart disease, and those who are infected with other pathogens, as well as those with incomplete medical records were excluded.

MPNP inclusion criteria

Chest CT shows early bilateral or unilateral lung consolidation, followed by liquefaction and necrosis in the consolidation area, forming multiple thin-walled cavities or cystic shadows that can fuse into large cavities, meeting the diagnostic criteria for necrotizing pneumonia.

Inclusion criteria for consolidation group

Chest imaging shows infiltration in more than one lung segment or lobe, and no progression to necrotizing pneumonia. Chest CT was carried out by using Brilliance CT 64 Slice [Philips Medical Systems (Cleveland) Inc.]. Patients with pulmonary tuberculosis, congenital lung cysts and lung abscesses were excluded. Considering that liver injury affects serum LDH levels, patients with diseases such as viral hepatitis and metabolic diseases that affecting the liver were excluded. Diagnostic criteria for liver injury: ALT > 3 times the upper limit of normal value (ULN), and the ratio of ALT measured value/ALT normal value upper limit to ALP measured value/ALP normal value upper limit is ≥ 5.

This study has been approved by Ethics Committee of Children's Hospital of Henan Province and all methods were performed in accordance with the relevant guidelines and regulations. Informed consent from a parent and/or legal guardian of the minor participant was taken for study participation. The hypothesis of this study was that LDH effectively differentiate between patients and healthy controls, and the area under the ROC curve for LDH is greater than 0.5. Based on the previous literature it was known that the area under the ROC curve for LDH was 0.836, and the sample size was estimated using the PASS15 at α = 0.05 (biparietal), β = 0.1, and the ratio of the groups was 1:1. It was found that a minimum of 13 patients and 13 controls, totaling 26, needed to be included. Considering a 10% loss to follow-up rate, the study included 15 patients and 15 controls, totaling 30. Among the remaining 3250 children with MP, the propensity score method was used to match them at a 1:2 ratio, as each MPNP group individual was matched with 2 non MPNP individuals with the most similar propensity score values. Finally, 128 children with MPNP met the criteria for necrotic group, and 118 children with MPP combined with pulmonary consolidation were met the criteria for the consolidation group.

Data collection

We obtained the MPP patients’ basic data, such as age, gender, course of disease at admission and bodyweight by retrospectively review. We used propensity score matching to match the two groups of patients to obtain a covariate-balanced sample between the two groups, and then collected clinical presentations, laboratory data and imaging findings from the sample.

The clinical manifestations mainly include high fever, shortness of breath, fine wet rales, wheezing, liver damage, and skin damage. Laboratory tests mainly include white blood cell (WBC) count, platelet (PLT) count, neutrophil percentage (NE%), C-reactive protein (CRP), Calcitonin (PCT), alanine transaminase (ALT), aspartate aminotransferase (AST), LDH content, D-dimer, fibrinogen, IgE, IgA, IgG and IgM. The imaging examination results mainly include the presence or absence of pleural effusion, lung consolidation, atelectasis, and pulmonary necrosis.

Statistical analysis

The statistical analysis was performed using SPSS 24.0 and R 3.60. The distribution of data in all groups was tested for normality of data distribution by Kolmogorov–Smirnov test, and data satisfying normal distribution were evaluated by t-test, expressed as x ± SD (mean ± standard deviation). For non-normally distributed data, Mann–Whitney rank sum test was used, expressed as median (quartile interval) [M (JOR)]. Comparisons between two groups of quantitative data were expressed as (%) by chi-square (χ 2 ) test or Fisher's exact probability method. Receiver operating characteristic (ROC) curve analysis was used to evaluate the value of LDH in the prediction and diagnosis of MPNP. P values were calculated using the two-tailed test. P  < 0.05 was considered statistically significant.

Firstly, compare the differences of indicators between the necrosis group and the consolidation group, and further conduct logistic regression analysis. If the independent variable has a P  < 0.1 in the results of a one-way logistic regression analysis, then it should be included in the multivariate logistic regression analysis. The independent variables were screened using the forward method and differences were considered statistically significant at P  < 0.05. The probability curve of LDH and MPNP incidence was draw using logistic regression model. LDH level were used as the prediction indicator. Receiver operating characteristics were plotted with sensitivity as the vertical coordinate and 1-specificity as the horizontal coordinate. At the same time, we find the best cut-off value of LDH by using the Youden's J statistic method and evaluated the relationship between LDH and MPNP incidence OR values using a restricted cubic spline function. The nonlinear relationship between the independent variable and the dependent variable were analyzed by the restricted cubic spline method that combines the spline function and logistic regression. With the best cut-off value of LDH as the reference value, the restricted cubic spline method was used to analyze the dose response relationship between LDH and MPNP. LDH was a continuous variable and four nodes (P5, P35, P65, P95) were selected based on their quantitative distributions and restricted cubic spline graphs were plotted in R 3.60 software. Finally, decision curve analysis (DCA) on LDH was performed. Decision curve analysis is a statistical method for evaluating clinical predictive models, diagnostic experiments, and molecular markers. Using the net benefit rate as the vertical axis and the high-risk threshold as the horizontal axis, DCA curves were plotted to comprehensively analyze whether LDH can generate effective clinical value in clinical application decisions with different probabilities.

Data availability

The datasets used and analyzed in the present study is available from the corresponding author on reasonable request.

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Acknowledgements

We acknowledge for the support from Henan Province Science and Technology Joint Construction Project (No. LHGJ20220712) and Henan Province Science and Technology Joint Construction Project (No. LHGJ20220724).

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These authors contributed equally: Ren Yanhong and Zhao Shuai.

Authors and Affiliations

Respiratory Department, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital Zhengzhou Children’s Hospital, Zhengzhou, 450018, Henan, China

Ren Yanhong, Zhao Shuai, Chen Dan & Sun Xiaomin

Henan International Joint Laboratory for Infectious Diseases in Children, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital Zhengzhou Children’s Hospital, Zhengzhou, 450018, Henan, China

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Y.R. and S.Z. designed and conceived the study; X. S., S. Z. and D. C. performed the experiments; Y. R. and S. Z. analyzed the data; S. Z. wrote the manuscript; Y. R. and X. S. revised the manuscript. All authors read and approved the final manuscript.

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Correspondence to Sun Xiaomin .

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Yanhong, R., Shuai, Z., Dan, C. et al. Predictive value of lactate dehydrogenase for Mycoplasma pneumoniae necrotizing pneumonia in children based on decision curve analysis and dose–response analysis. Sci Rep 14 , 9803 (2024). https://doi.org/10.1038/s41598-024-60359-1

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Received : 06 September 2023

Accepted : 22 April 2024

Published : 29 April 2024

DOI : https://doi.org/10.1038/s41598-024-60359-1

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