PONE-D-22-03892Patterns of Polysubstance use among Adults in Malaysia – A Latent Class AnalysisPLOS 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: 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: Though the study is timely and highlights the prevalence of poly-substance use among the adult Malaysian population, as well as the use of kratom, the authors must address a few issues based on the review comments before the paper can be accepted for publication.

Introduction

Pg. 2 – paragraph two – most people with multiple substance use disorders (SUDs)….

National Anti-Drugs Agency (NADA) has compiled and described the growing prevalence of poly-drug use among people who use drugs (PWUDs) in Malaysia. Hence, the authors can incorporate some information on poly-substance use in the adult population of PWUDs in Malaysian in the introduction section of their manuscript.

Revision required – In Southeast Asia countries, ketum or kratom (leaves from the Mitragyna speciosa Korth. trees)…

Revision required – Kratom is an indigenous plant of Southeast Asia, and it is reported to have dose-dependent effects as opioid and stimulants.

Kratom (ketum) do not cause/produce hallucinations – please remove the word hallucination from the text. (Obtain opioid-like effects).

Can the authors also provide a rationale as to why the study aimed to determine the patterns of poly-substance use in the adult Malaysian population. What health risks the authors intend to examine?

Methods

Provide an explanation for targeted residence in non-institutionalized living quarters.

How the data collectors ensured that the respondents were willing to disclose their illicit drug use status through the self-administered questionnaire. This is because illicit drug use is illegal in Malaysia, and thus openly self-reporting their illicit drug use status can cause them to experience legal problems with the enforcement authorities in Malaysia.

Did the study also captured other illicit drugs such as ketamine, or other new psychoactive substances (NPSs) used by the respondents.

Were the respondents regular, irregular or those with substance use disorders (SUDs)? Did the authors categorised the respondents as recreational drug users or those with SUDs.

Results

Any reasons why the sample size was larger for urban respondents than respondents from rural setting.

What are the definitions of B40, M40 and T20? Please provide details of the terms used in the methods section of the manuscript.

Discussion

This study highlights an updated or current epidemiological data regarding poly-substance use in the adult population of Malaysia.

Revision needed - This finding was supported by previous studies in Malaysia indicating that people who use drugs (PWUDs) commonly used kratom to abstain from illicit drugs and to manage withdrawal symptoms from both opioid and stimulant use [25,26,34].

What are the authors trying to mean by pure kratom alone? Brewed juice, kratom juice without adulterants, etc.

How can the relevant authorities address kratom cultivation and distribution issues in Malaysia? Please explain what the legal consequences are of using or possessing kratom in Malaysia.

Those who take up marijuana later would be less predisposed to other illicit drug use than those who take it up early – any reference for this.

Additional comments

There are several grammatical errors and poor structuring of sentences. Please look into it.

Reviewer #2: The rationale of the study was not clearly stated. The importance of studying polysubstance abuse and its implication was not clearly stated.

in the methodology, the data collection was not clear whether the data was extracted from a previous record or from interviewing the study population.

The type of substance in table 2 was not specified.

Class 3, was proposed as one of the three Classes of Polysubstance use based on the LCA model analysis. However, it is not clear what is the significance of this class as the use of substances in this class was either non or negligible.

The point about the kratom in the discussion made was beyond the scope and not supported by data from this study.

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Reviewer #1: No

Reviewer #2: No

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Patterns of Polysubstance use among Adults in Malaysia – A Latent Class Analysis

PONE-D-22-03892R1

Dear Dr. Rodzlan Hasani,

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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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

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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

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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

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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: The authors have addressed all the comments. All required questions have been answered and that all responses meet formatting specifications.

Reviewer #2: interesting study and the informative about polysubstance and ketum use. Authors had addressed all comments made by reviewer.

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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: Yes: DARSHAN SINGH

Reviewer #2: Yes: Mohd Azhar

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