PONE-D-22-29795Revisiting the Factor Structure of the Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2): Evidence for a Bifactor Model in Individuals with Chiari MalformationPLOS ONE

Dear Dr. Allen,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

==============================Update the literature review with more recent literature. Please also complete the following minor amendments:  1. “An estimated 80-100 million American adults experience some form of chronic pain and that estimate will undoubtedly increase as the population continues to age”. It will be better if the authors can use a newer reference. These statistics may have been recently updated. In addition, all the studies that were reviewed in the introduction section are from before 2017. It is necessary to mention the newer papers from the last three years, as well.

2. It can be better if you present your personal hypotheses and reasons (from the clinical point of view) for your results in the discussion section. For example, your results showed the strongest support for the bifactor model, suggesting that SF-MPQ-2 item responses are due to both a general pain factor and a specific pain factor that is orthogonal to the general pain factor. This is a valuable find. In addition to the results of your statistical analysis, what do you think is the reason for this from the clinical point of view? You can discuss it to open new windows for future research.

3. Previous studies showed a relationship between CSF dynamic parameters and clinical signs such as pain [10.1016/j.wneu.2018.05.108] [10.1038/s41598-020-72961-0]. Do you think that future studies can consider this as a factor to develop the questionnaire?

Please also correct these typo errors:

1. “… Like Dworkin et al. (2009), Dworkin et al. (2105) performed separate…”. Correct “(2105)”

2. “Missing Completely at Random (MCAR)” should be changed to “missing completely at random (MCAR)”.

3. Write the full SEM form "Structural Equation Modeling" the first time you used it in the manuscript (page 13), not page 14.​

==============================

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Academic Editor

PLOS ONE

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Additional Editor Comments (if provided):

Thank you for submitting your manuscript to PLOS ONE. Sincere apologies for the delay in reviewing we invited close to 20 reviewers. The statistician's review indicates the statistics are sound.

The decision is Minor Revisions. Please update the introduction with more recent literature. Please also complete these minor modifications:

1. “An estimated 80-100 million American adults experience some form of chronic pain and that estimate will undoubtedly increase as the population continues to age”. It will be better if the authors can use a newer reference. These statistics may have been recently updated. In addition, all the studies that were reviewed in the introduction section are from before 2017. It is necessary to mention the newer papers from the last three years, as well.

2. It can be better if you present your personal hypotheses and reasons (from the clinical point of view) for your results in the discussion section. For example, your results showed the strongest support for the bifactor model, suggesting that SF-MPQ-2 item responses are due to both a general pain factor and a specific pain factor that is orthogonal to the general pain factor. This is a valuable find. In addition to the results of your statistical analysis, what do you think is the reason for this from the clinical point of view? You can discuss it to open new windows for future research.

3. Previous studies showed a relationship between CSF dynamic parameters and clinical signs such as pain [10.1016/j.wneu.2018.05.108] [10.1038/s41598-020-72961-0]. Do you think that future studies can consider this as a factor to develop the questionnaire?

Typo errors:

1. “… Like Dworkin et al. (2009), Dworkin et al. (2105) performed separate…”. Correct “(2105)”

2. “Missing Completely at Random (MCAR)” should be changed to “missing completely at random (MCAR)”.

3. Write the full SEM form "Structural Equation Modeling" the first time you used it in the manuscript (page 13), not page 14.

Kindest regards,

Leica

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

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Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Chiari malformation is a complicated disorder and pain is one of the controversial challenges related to this disorder. Because pain is a complex and multifactor phenomenon. Despite extensive research and study, there is still much that is not fully understood about it. So, revisiting the pain questionnaire can be really interesting for the readers of PloS One. The authors strived to evaluate the factor structure of the SF-MPQ-2 to measure the multidimensional qualities of pain and total pain. They evaluated the fit of four competing measurement models in 552 adults (73 cases contained missing item-level data points) diagnosed with Chiari malformation. They hypothesized that continuous, intermittent, neuropathic, effective, and general pain factor scores will relate uniquely and positively with anxiety, depression, and stress. The authors showed that most of the SF-MPQ-2’s reliable variance is explained by a general pain factor and that the instrument can be modeled unidimensionally and scored as a general pain measure. Their results also showed that the general and affective pain factors in the bifactor model uniquely predicted pain-related external criteria but the continuous, intermittent, and neuropathic factors did not. This study is well-designed, and the method and result sections are quite clear for the readers. The introduction section should be updated with some newer papers. Taken together, this finding provides strong support for calculating and interpreting raw SF-MPQ-2 total scores for a general pain to construct. Hence, I strongly believe that this study provided important practical data for neurosurgeons and has good potential for future citations. So, I suggest publishing this paper after considering the following minor comments.

1. “An estimated 80-100 million American adults experience some form of chronic pain and that estimate will undoubtedly increase as the population continues to age”. It will be better if the authors can use a newer reference. These statistics may have been recently updated. In addition, all the studies that were reviewed in the introduction section are from before 2017. It is necessary to mention the newer papers from the last three years, as well.

2. It can be better if you present your personal hypotheses and reasons (from the clinical point of view) for your results in the discussion section. For example, your results showed the strongest support for the bifactor model, suggesting that SF-MPQ-2 item responses are due to both a general pain factor and a specific pain factor that is orthogonal to the general pain factor. This is a valuable find. In addition to the results of your statistical analysis, what do you think is the reason for this from the clinical point of view? You can discuss it to open new windows for future research.

3. Previous studies showed a relationship between CSF dynamic parameters and clinical signs such as pain [10.1016/j.wneu.2018.05.108] [10.1038/s41598-020-72961-0]. Do you think that future studies can consider this as a factor to develop the questionnaire?

Typo errors:

1. “… Like Dworkin et al. (2009), Dworkin et al. (2105) performed separate…”. Correct “(2105)”

2. “Missing Completely at Random (MCAR)” should be changed to “missing completely at random (MCAR)”.

3. Write the full SEM form "Structural Equation Modeling" the first time you used it in the manuscript (page 13), not page 14.

Reviewer #2: The paper is well-written and structured, and the statistical analysis is well-conducted in all of its parts/aspects (description of the data, descriptive preliminaries, main analysis, model selection, and validation). The reference to the literature for each statement/choice made, and the use of more sophisticated statistical tools when necessary, are aspects that deserve to be appreciated. As such, I suggest to accept the paper as it is.

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Reviewer #1: Yes: Seifollah Gholampour

Reviewer #2: No

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Revisiting the Factor Structure of the Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2): Evidence for a Bifactor Model in Individuals with Chiari Malformation

PONE-D-22-29795R1

Dear Dr. Allen,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Leica S. Claydon-Mueller

Academic Editor

PLOS ONE