Host Led Harm Reduction Approach Among Men Who Have Sex With Men Who Engaged in Chemsex in Bangkok, Thailand: A Pre-Implementation Study (HAMMOCK)

April 2, 2026 updated by: Institute of HIV Research and Innovation Foundation, Thailand
This study evaluates the pre-implementation phase of a host-led harm reduction model for men who have sex with men (MSM) engaging in chemsex in Bangkok, Thailand, focusing on understanding harms, contexts, and needs to develop a tailored intervention.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

HAMMOCK is a cross-sectional mixed-methods study designed to explore chemsex practices among MSM, including both hosts and guests, as well as key stakeholders such as CSOs, hospital staff, and police.

The study aims to:

  • Explore substance-related, sexual health, mental health, and socio-legal harms
  • Understand the context and dynamics of private chemsex parties
  • Co-develop a novel host-led harm reduction model
  • Identify barriers and facilitators to implementation The study includes both quantitative (self-administered questionnaires) and qualitative (in-depth interviews) components and follows a two-phase approach: exploration and preparation phases under the EPIS framework.

Study Type

Observational

Enrollment (Estimated)

76

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Thailand
    • Bangkok
      • Pathum Wan, Bangkok, Thailand, 10330
        • Recruiting
        • Tangerine Clinic, Institute of HIV Research and Innovation
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Recruit chemsex party hosts, chemsex party guests, representatives from the CSOs, government hospital, police organization G1: Chemsex party hosts 1. Have ever hosted a chemsex party at least 2 times in the past 6 months.

G2: Chemsex party guests

1. Have ever attended a chemsex party at least 2 times in the past 6 months.

G3: CSOs 1. Currently working in a CSO 3. Hold a role or perform a duty related to chemsex-related incidents or drug use for more than 3 months.

G4: Government hospitals

  1. Currently working in a government hospital.
  2. Hold a role or perform a duty related to chemsex-related incidents or drug use for more than 3 months.

G5: Police officers

1. Currently working in a police organization. 3. Hold a role or perform the duty related to chemsex-related incidents or drug use for more than 3 months.

Description

Inclusion Criteria:

  • MSM aged ≥18 years
  • Able to communicate in Thai

  • Specific by group:

    • Chemsex hosts: hosted ≥2 times in past 6 months
    • Chemsex guests: attended ≥2 times in past 6 months
    • CSO / hospital / police staff: working ≥3 months in related roles
  • Provide informed consent

Exclusion Criteria:

• Unable to provide informed consent (e.g., under substance influence at consent)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Single Arm - Mixed-method Harm Reduction Model Development
Participants (chemsex party hosts, guests, CSO staff, hospital staff, and police officers) will participate in a mixed-method study consisting of two phases (Exploration and Preparation) to assess harms related to chemsex and to develop and refine a novel harm reduction model for private chemsex party settings.
Behavioral: Self-administered questionnaire assessment

Participants (chemsex party hosts and guests) will complete structured self-administered questionnaires to assess:

  • Substance use patterns and related harms
  • Sexual health risks (e.g., condom use, HIV/STI testing, PrEP/ART adherence)

  • Mental health status using validated tools:

    • Patient Health Questionnaire-9 (PHQ-9)
    • Generalized Anxiety Disorder-7 (GAD-7)
  • Socio-legal harms including stigma and discrimination
Behavioral: Semi-structured in-depth interviews (IDIs)

All stakeholders will participate in semi-structured in-depth interviews:

  • Exploration phase: guided by EPIS framework

  • Preparation phase: guided by

    • Theoretical Domains Framework (TDF) (hosts & guests)
    • Consolidated Framework for Implementation Research (CFIR) (organizational stakeholders)

The interviews aim to:

  • Identify harms associated with chemsex
  • Explore current practices and contexts
  • Identify barriers and facilitators
  • Inform development and refinement of a harm reduction model
Behavioral: Development and refinement of harm reduction model

A novel four-pronged harm reduction model will be developed and refined based on quantitative and qualitative findings.

Domains include:

  • Substance use harm reduction
  • Sexual health harm reduction
  • Mental health harm reduction
  • Socio-legal harm reduction

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Substance use-related harm assessed by self-administered questionnaire
Time Frame: Baseline (during Exploration phase, prior to model development)

Substance-related harms will be assessed using a structured self-administered questionnaire. The assessment includes:

  • Patterns of substance use (snorting, injecting, ingesting, anal insertion)
  • Frequency of use
  • Physical harms (e.g., injection-related injuries, overdose)
  • Psychological harms (e.g., substance dependence) This is a descriptive assessment; no composite scale score is generated.
Baseline (during Exploration phase, prior to model development)
Sexual health risk behaviors assessed by self-administered questionnaire
Time Frame: Baseline (during Exploration phase, prior to model development)

Sexual health risks will be assessed using a structured questionnaire including:

  • Number of sexual partners
  • Condom use
  • HIV/STI testing history
  • Self-reported HIV status
  • Pre-exposure prophylaxis (PrEP) use and adherence
  • Antiretroviral therapy (ART) adherence among participants living with HIV This is a descriptive assessment; no composite scale score is generated.
Baseline (during Exploration phase, prior to model development)
Depression severity assessed by Patient Health Questionnaire-9 (PHQ-9)
Time Frame: Baseline (during Exploration phase, prior to model development)

Depression will be assessed using the Patient Health Questionnaire-9 (PHQ-9):

  • Score range: 0 to 27

  • Interpretation:

    • 0-4: Minimal depression
    • 5-9: Mild
    • 10-14: Moderate
    • 15-19: Moderately severe
    • 20-27: Severe Higher scores indicate worse depression severity
Baseline (during Exploration phase, prior to model development)
Anxiety severity assessed by Generalized Anxiety Disorder-7 (GAD-7)
Time Frame: Baseline (during Exploration phase, prior to model development)

Anxiety will be measured using the Generalized Anxiety Disorder-7 (GAD-7):

  • Score range: 0 to 21

  • Interpretation:

    • 0-4: Minimal
    • 5-9: Mild
    • 10-14: Moderate
    • 15-21: Severe Higher scores indicate worse anxiety
Baseline (during Exploration phase, prior to model development)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Perceived stigma and socio-legal harm assessed by structured questionnaire
Time Frame: Baseline (during Exploration phase, prior to model development)

Socio-legal harms will be assessed using a structured questionnaire adapted from the CLYMAX study, including:

  • Internalized stigma related to chemsex
  • Perceived discrimination (family, workplace, social)
  • Legal risks and experiences This is a descriptive assessment; no composite scale score is generated.
Baseline (during Exploration phase, prior to model development)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Institute of HIV Research and Innovation Foundation, Thailand

Collaborators

International AIDS Society

Investigators

  • Principal Investigator: Jakkrapatara Boonruang, MD, Institute of HIV Research and Innovation (IHRI)

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 17, 2025

Primary Completion (Estimated)

February 17, 2027

Study Completion (Estimated)

December 30, 2028

Study Registration Dates

First Submitted

March 22, 2026

First Submitted That Met QC Criteria

April 2, 2026

First Posted (Actual)

April 6, 2026

Study Record Updates

Last Update Posted (Actual)

April 6, 2026

Last Update Submitted That Met QC Criteria

April 2, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • IHRI037

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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