PONE-D-24-22453Prediction of testosterone deficiency using different screening indexes in adult American men: an NHANES cross-sectional studyPLOS ONE

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Additional Editor Comments:

It is an interesting study in which authors invesigated association testosterone deficiency and different screening indexes. The reviewers have raised some comments, and the authors are suggested to address them carefully.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

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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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

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: Dear editor and authors

I am very pleased and honored to review a manuscript for PLOS ONE. The article entitled “Prediction of testosterone deficiency using different screening indexes in adult American men: an NHANES cross-sectional study” provides a cross-sectional survey from the National Health and Nutrition Examination Survey (NHANES) database aimed at evaluating the role of metabolic indexes in predicting testosterone levels and testosterone deficiency. The association between metabolic disease (e.g., Type 2 Diabetes, overweight/obesity, etc.) and testosterone deficiency is well established. Nevertheless, many patients might be asymptomatic or present very non-specific symptoms, making the diagnosis of testosterone deficiency in this clinical setting still challenging, and contributing to the misdiagnosis of this condition. Current literature data in this clinical context are scanty and the data reported in the study provides a very interesting insight, thus contributing to early diagnosis and treatment of hypogonadal patients.

After carefully reading the whole manuscript, my comments and suggestions are reported below in bulleted list.

1) TITLE and ABSTRACT

� The title is clear and coherent with the text. The abstract is also well-structured: all sections are summarized in a clear, balanced, and comprehensive way.

� I suggest to add in this paragraph the type of study design (cross-sectional survey), since it was reported only in the “Introduction” but not in this section of the manuscript.

2) INTRODUCTION

� In the early section of this paragraph, I suggest to describe more in detail the relationship between testosterone decline/hypogonadism and metabolic diseases (considering both the pathophysiological and clinical implications). I also suggest to include in this overview a brief explanation of the “functional hypogonadism” that often characterize these subjects.

� In this paragraph authors states that “Considering visceral obesity ad a symptom of low testosterone, …”. I suggest to replace the term SYMPTOM with SIGN, since obesity represents a constitutional feature.

� The description of the LAP index might be misleading, since its independency from serum glucose level might be perceived by the reader as a limitation. However, the wide variability in glucose levels and the potential benefit of this index (as well as VAI) in estimating the visceral adiposity should be pointed out more clearly. From this perspective, being independent from serum glucose concentration might actually represent an advantage for these indexes.

� At the end of the paragraph authors point out that data were derived from the NHANES database; I suggest consider to move this information into the next paragraph (Methods).

3) METHODS

� Was this study approved by ethical committee? If so, I suggest to add the “approval number” or the “registration code”. All participants signed a written informed consensus before being enrolled the study.

� When presenting the inclusion criteria, I suggest to briefly describe why you chose “20 years” as the cut-off for inclusion. On the one hand, due to the high prevalence of overweight in the American population, including such young patients might represent a strong point. On the other hand, including males older than 50 years might introduce a potential confounding factor, since in these subjects the testosterone reduction is at least in part cause by physiological reduction of testicular steroidogenesis over time, regardless from the presence of metabolic disease.

� When describing the technique for sample collection, I suggest to also add the time of collection (e.g., “samples were collected in the morning (before 10.00 a.m.) after at least eight hours of fasting”).

� When describing all indexes considered, I suggest to point out the role of HOMA-index to make it explicit is role (I suppose it considered as a “gold-standard reference”)

� Finally, when describing cut-off for diagnosing diabetes, please correct a small typing error ("blood glucose levels" is expressed in mg/dL instead of mmol/L: it should be 7.1 mmol/L and not 7.1 mg/dL).

When considering specifically the “statistical analysis section”:

- I suggest to add in the text whether and how continuous variables were testes for normal distribution (e.g., Shapiro Wilk test) and if/how were they transformed if requested (was testosterone serum level normally distributed or was it necessary to transform it before regression analysis?);

- I suggest to rephrase when describing the types of regression used, in order to make it simpler for the reader to understand the logic underlying the statistic process (i.e., testosterone was considered both as continuous variable (➝ linear regression) and dichotomic variable (➝ logistic regression)).

- When reading the manuscript and tables I guess that multivariate analysis was performed rather than simple ones: from this perspective I suggest to make it explicit into the text and adding into tables (i.e., table 2) the statistical parameters of every model (R, R2, p (test F) coefficient for linear regression and Likelihood ratio, R2, adjusted R2 and p for logistic one).

- Finally, consider making explicit that also subgroup analyses were performed to test the reliability of the predictive potential of some index (i.e., TyG_WHtR).

4) RESULTS

� Information provided at the beginning of the paragraph (patients ages > 20 years) should be removed, since it is already present in the “Method” section.

� The first phrase of the section “screening index for predicting TD” should also be moved into the introduction. I suggest to start this paragraph by directly describing the main results of the study.

5) DISCUSSION and CONCLUSIONS

� I consider to re-structure the whole paragraph and consider to move some information into the “Introduction”, as the description of hypogonadism (despite being interesting and well described, I suggest to eliminate the description of primary and secondary hypogonadism since it is out of the primary focus of the manuscript. I rather suggest adding few considerations about the so called “functional hypogonadism”).

� I also suggest moving into the “Introduction” the description about metabolic indexes (BMI, WC, LAP and VAI) and testosterone deficiency, as well as the role of insulin-resistance (IR) and testosterone deficiency.

� Authors also describe in detail the pathophysiological role of estrogen and leptin on pituitary-gonadal axis. Although being very interesting and well described, this information might be out of the main scope of the present manuscript. I suggest to resume this section in one phrase (into the “introduction”) highlighting the potential role of adipose tissue in reducing plasma testosterone due to the aromatization processes.

� More in general, the “Discussion” should be enriched by pointing out the potential benefits of applying these indexes in clinical practice, as well as advantages in early diagnosis and treatment of hypogonadism.

� When discussing the limitations of the study I suggest to consider the following aspects: 1) discuss that making diagnosis of testosterone deficiency based only on a single measurement may lead to overestimation of hypogonadism; 2) despite being very important in the clinical evaluation and treatment of these patients, the presence of symptoms (i.e., decreased energy, depression, reduced libido and erectile deficiency) does not allow per se to diagnose testosterone deficiency.

6) FIGURES

� Data are displayed accurately, are easy to interpret and are consistent with data analysis presented in the manuscript.

� All tables and figure present an accurate legend.

After addressing the above issues, I believe this manuscript is highly worthy of publication. I look forward to the authors resolving my concerns.

Kind regards.

Reviewer #2: The manuscript is technically sound and the data supported the conclusions. Statistical analysis is adequate and performed appropriately and rigorously. The authors have made all data underlying the findings in their manuscript fully available. The manuscript is presented in an intelligible fashion and written in standard English, though there are few spelling mistakes. For instance:

line 19: indicators not inicators

line 24: exhibited not exhibitrd

line 27: indexes not indexses

line54: injection not ejection

line 219: mediator not medicator

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Reviewer #1: No

Reviewer #2: Yes:  Professor Sikiru Adetona OLURODE

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Prediction of testosterone deficiency using different screening indexes in adult American men: an NHANES cross-sectional study

PONE-D-24-22453R1

Dear Dr. Feng,

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.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Shaonong Dang, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. 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: Dear authors,

I believe the authors have addressed all of my concerns, and the manuscript is now suitable for publication!

Reviewer #2: Authors have satisfactorily addressed all the concerns raised earlier. All the identified spelling mistakes have been corrected.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: Yes:  Professor Sikiru Adetona OLURODE

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