PONE-D-20-26437

Associations of gamma-glutamyl transferase with cardio-metabolic diseases in people living with HIV infection in South Africa

PLOS ONE

Dear Dr. Nguyen,

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.

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Ethan Morgan

Academic Editor

PLOS ONE

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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: Partly

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

Reviewer #1: I Don't Know

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: Thank you for this detailed analysis. I notice the statistical effort in compiling the results. I am a clinician. I cant comment on the statistical methodology of the study. My comments are more from a clinician's perspective that I hope would make sense as follows.

Main comments:

1. The authors highlight that the association between GGT and metabolic syndrome/ CVD risk has already been established in general population. What would be the reason to expect such an association would not apply to PLWH?

2. I am sorry to say that I am not sure what would be the clinical use of the information of this meticulous analysis. Are we proposing that we should be screening patients for CVD/ DM/ etc when the GGT is raised? Or, should we dismiss further management of raised GGT when any of the identified conditions are present?

3. In practice, most of the patients with raised GGT have elevated ALT and AST too (indeed Table 1 also agrees with this statement). We interpret liver profile and not just one of the liver enzyme to define clinical abnormality. How do we propose to use the study information for management of those patients?

4. I am not sure the quarters of GGT used for the analysis are clinically relevant. The study's GGT quarters Q1, Q2 and Q3 are all within refence range and normal. Should we not carry out the analysis between all within reference range compared with those with elevated range according to the MACS classification of abnormal liver enzymes?

5. I notice the authors have acknowledged that they did not investigate the roles of viral hepatitis and cART medications. I think these are quite important omissions particularly considering the background prevalence of the infections in South Africa.

6. Unless I am mistaken, the analysis included even one unit of alcohol per time of study definition in the alcohol consumption group. This is strictly correct however not clinically helpful. Essentially what we need is to identify the threshold of consumption beyond which GGT would rise.

7. I notice that the majority of the study patients were women? Any reason for this? Would this have caused a bias?

8. As stated earlier, I am not a statistician. I am interested to understand how nearly every factor investigated in this study had significant association with raised GGT? Some of the findings don't make immediate sense to me; e.g. why would CD4 count have such a relationship with raised GGT?

Minor

1. Use of Framingham score in a population of non-White patients mostly living in rural areas may create a majour issue with the validity of the calculated CVD risk.

2. The results sections are full of mathematical evidence with little narrative on their clinical implications.

Reviewer #2: The manuscript entitled “Associations of gamma-glutamyl transferase with cardio-metabolic diseases in people living with HIV infection in South Africa” and authored by Nguyen et al., set out to investigate the associations of GGT with cardio-metabolic diseases and CVD risk in a group of South Africans living with HIV. To achieve this, the authors conducted a cross-sectional study which included randomly recruited HIV-infected adults. Homeostatic model assessment for insulin resistance, and associations between GGT and cardio-metabolic trait were determined. The authors observed associations of GGT with a number of cardiovascular disease risk factors, but not with diabetes, and concluded that GGT levels were associated with cardio-metabolic variables in the HIV-infected subjects but independent of HIV specific attributes, with the suggestion that GGT evaluation maybe included in CVD risk monitoring strategies in people living with HIV if the results is confirmed in a longitudinal study.

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Comments:

1. The authors mentioned at the beginning of the Discussion that the study was the first ever to investigate the association of GGT with cardiovascular risk factors in HIV infected Africans (Lines 228-229 and 291-293). This is not correct; the EndoAfrica study in the Western Cape Province of South Africa has done a similar study already.

(1. https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-020-05173-6)

(2. https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-016-2158-y)

I will suggest that the authors take a look at the studies to see how to re-frame their study/story.

2. The authors also observed that the association of GGT with almost all the parameters that were investigated was similar to what has been shown in various populations; both disease conditions and control groups. This suggests that the study is not adding anything new to subject.

3. Referring to HIV infected patients/subjects as “a sample” is not correct and should be corrected throughout the manuscript (E.g. Lines 18 and 36-37 in the Abstract section).

4. Lines 93-94 in the Method section. The sentence does not indicate the number of times the BP was taken, which is important in this case.

5. Lines 99-102. The sentence is not clear and needs to be revised.

6. Lines 102-104. The sentence needs to be referenced.

7. Line 106. I will suggest that you either say "as previously described" or you would have to put the mathematical equation.

8. Lines 139-140. I will suggest that the first sentence in the Results section is moved to the Methods section.

9. There are minor typographical errors that needs to be corrected. E.g. Line 105. The word “Chemiluminescence” has an extra “e”.

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Reviewer #1: Yes: Kaveh Manavi

Reviewer #2: No

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PONE-D-20-26437R1

Associations of gamma-glutamyl transferase with cardio-metabolic diseases in people living with HIV infection in South Africa

PLOS ONE

Dear Dr. Nguyen,

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.

The reviewer's suggest a few additional minor changes. Please attend to these, I look forward to receiving your revision in due time.

Please submit your revised manuscript by Feb 14 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Ethan Morgan

Academic Editor

PLOS ONE

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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 #2: (No Response)

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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 #2: Partly

**********

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

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 #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 #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 #2: The authors have addressed most of the comments that were raised, however, the major concern has not been addressed.

Even though the authors have incorporated the suggested EndoAfrica project references, they still have it in the Introduction section that “the association between gamma-glutamyl transferase (GGT) and CVD risk, while confirmed in general populations, has not been investigated in the HIV-infected“. I think this needs to be corrected. Secondly, I do not agree to the revisions made to the first sentence of the Discussion section which says that “this study is among the first to investigate the associations of serum GGT with CVD risk factors in HIV-infected Africans”. The study is not the first and the authors would just have to accept that fact.

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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 #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Associations of gamma-glutamyl transferase with cardio-metabolic diseases in people living with HIV infection in South Africa

PONE-D-20-26437R2

Dear Dr. Nguyen,

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,

Ethan Morgan

Academic Editor

PLOS ONE

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