PONE-D-21-22797

Key Risk Factors for Substance Use among Female Sex Workers in Soweto and Klerksdorp, South Africa: A cross-sectional study

PLOS ONE

Dear Dr. Yeo,

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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: Yes

Reviewer #2: No

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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 opportunity to review. Apologies for brevity. Your reviewer is unwell with Covid but I wanted to get this back so the authors could address speedily.

The subject matter explored is highly relevant and speaks to understanding and meeting the needs of a key generally marginalised population. Congrats!

The literature review is appropriate. There are however a few brief points of reflection.

In the abstract:

1. At line 37: Include a note about which survey? was it developed for this study? Evaluating what exactly? Validated?

2. At line 40, with reference to the text “key risk factors of alcohol and drug use” it might assist if this was clearer on whether this referred to Risks for or risks resulting from or all risks?

In the introduction

3. At lines 58 and 59, the authors might perhaps consider using more current references. For line 58 The authors need to cite more current publications such as the most recent World Drug Report, which will have been published in the period since this manuscript was probably submitted.

4. Line 60 refers to a diagnosis of drug use. Were the authors intending to refer to a diagnosis of substance use disorder? Can drug use be “diagnosed”?

5. The final sentence of the first paragraph at lines 62 and 63, This statement is not supported by the provided stats. The sentence should perhaps read "...vary widely and this is likely a consequence of cultural and other environment factors" This statement would itself need a reference.

6. At line 86, Should there be centres specifically dedicated to FSW? Would this not further marginalize and stigmatize this population?

7. At line 87, the text “access to the few treatment centres is limited” refers. In what way is access limited? Some brief reflection on this might assist.

8. At line 89, there is reference to competing financial priority while in treatment. In what way? Could the authors provide a brief text for clarity in the manuscript.

9. At line 112 there is an appropriate refence to relationship to viral suppression consequent upon poor adherence. The links need to be stated more explicitly here and in terms of reduces access to health care in the next sentence, to clearly set the scene.

10. At line 117, The correct note about substance use being currently infrequently studied, as well needs to be more explicit. What about the substance use is infrequently studied? Is it substance use patterns? Is it substance use in general. I know what the authors are referring to but the writing needs to be more explicit for any reader.

In the Methods Section

11. At line 123, Is this manuscript reporting on two studies, or is it reporting on the findings of data collected at two sites at different times? Do these studies have separate Ethical clearance or is the newer sample an extension of the original approval?

12. At line 124, Brief description to link to the next sentence, RDS methodology, where an initial group of respondents assembled via convenience sampling are asked to invite additional participants from within their network" or something along those lines...

13. At line 133, the statement indicating the population size of Soweto needs a reference.

14. At line 144: As I am familiar with the implementing partner landscape in South Africa, I know what this means, but a reader from elsewhere might not be clear. This sentence should more explicitly clarify what these programmes are, what they do so as to clearly link the reader to why it is that they would have access to and the trust of FSW's

15. At line 157, Per above , perhaps some brief context into what the sex worker programme is.

16. At line 168 regarding data collection, what is meant by privately and collaboratively? Could this be made clearer in the text of the article?

17. In general the data collection process is not clear. The authors should seek to describe this in a way that is easy to follow and replicate.

18. At line 174 the authors refer to RDS assumptions and how these were managed. Which assumptions specifically?

19. At line 181 the following text refers “A detailed description of all measures used has been included in other papers” Please still at least list the measures or at least mention they are detailed below. (Having subsequently read further) Seeing as they are detailed below I'm not sure this sentence is essential)

20. At line 185, could the authors please clarify “cognitive interviews”? This can be confusing, particularly for this population as this is so often used in reference to law enforcement procedures.

21. The authors refer to physical and sexual use by partner throughout the manuscript. Is this correct or is it meant to refer to “abuse”. If “use is correct, please define?

22. My initial feeling was that the tables were possibly cumbersome, but they are in fact very handy, and I hope they can be retained in the final publication.

The authors have done an excellent job of characterising this population at these sites and eliciting their risk profiles for harmful substance use.

This material is not only suitable fir publication but will add great value in the consideration of responsive service provision for this key population. It should certainly be considered for publication with these minor revisions.

Authors have largely adhered to the STROBE recommendations, which apply to this type of study. They should refer more explicitly to the ways in which they have done so, and this might assist in addressing some minor gaps. For example, with this population is is especially important to consider ethical issues and speak to how potential bias has been addressed.

Per my input above, the procedures of the study could be described somewhat more explicitly so as to assist with replicability.

The manuscript is well organized but some clarifications and suggested above might assist in making the material more accessible to a broader readership.

This manuscript in my view does not contain an NIH-defined experiment of Dual Use Concern

Reviewer #2: Overall, really interesting paper with really interesting findings. There is just one piece that concerns me is drug use in the past month for Klerksdorp population and drug use in the past year for the Soweto population. See my last comment for suggestions on how to address this. All other comments are minor revisions.

Line 116-117 The intro section is full of strong statistics about SU in FSW populations. It is a bit of a contradiction to say something has been infrequently studied, when you have presented several articles to support SU in FSW populations (Line 65-68, 70, 72,77). The sentence should read “despite the high prevalence of trauma and mental health, gaps exist when focusing on binge drinking and drug use (although I do think you provided evidence that there is no gap when focused on drug use). The focus of this study is to describe the prevalence of self-reported binge drinking, and associated risk factors” or something similar. I think just a simple reivision will address this

Line 124 “enroll” Small spelling error

Line 126-127 “The full methodology from the Soweto study has been extensively described previously (7)” Language could be a better. For example: “The methods from the Soweto study has been throughly described in previous publications (7)”



Keep language consistent. Sometimes you utilize “FSW” and sometimes “woman.” For consistency, choose one! (End of line 136).


Line 137 “informal sex work was also paid for in beer” Do you have a citation for this?

Line 168 “Post enrollment” Another small spelling error.

Line 411-413 This is interesting and could also be a focus of future research. In what circumstances are FSW using both?

Line 450-452 The focus on HIV and ART feels a little out of place. I understand the big picture relationship, but how does this relate to the objective of the analysis which was to determine the prevalence and associated risks of binge drinking and drug use? 
Other limitations: cross sectional design.

Line 455: Because the Kleksdorp population was only asked about past month drug use, was this adjusted to reflect what the past year use would be? This assumes that every month has similar patterns of drug use, which I think is a feasible assumption. This could also explain why drug use was higher in Soweto compared to Kerksdorp. I think this is a glaring problem that needs to be adjudicated in either the methods to explain how you adjusted for this discrepancy or in the results, where you use the one month report to predict one years use, using the assumption the the report of one month's use is reflective of use in all the other months. This may change your results.

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Reviewer #1: No

Reviewer #2: No

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Key risk factors for substance use among female sex workers in Soweto and Klerksdorp, South Africa: A cross-sectional study

PONE-D-21-22797R1

Dear Dr. Yeo,

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,

Yukiko Washio, Ph.D.

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: No

Reviewer #2: No

**********

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: Initial comments have been sufficiently addressed and manuscript reads strongly and clear. A single additional minor recommendation might be where it is said that FSW'w were used to identify additional participants. Could the authors consider a word or phrase to say this more sensitively for what is a vulnerable population?

Reviewer #2: As I mentioned before, I really enjoyed reading this paper. Great job with the revisions. Best of luck!

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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: No