Table 4

Methodology at a glance

	Phase 1 (formative phase)		Phase 2 (quantitative cross-sectional survey)	Phase 3 (explanatory phase for formulating interventions)
	Literature review	Qualitative interview	Phase 2 (quantitative cross-sectional survey)	Explanatory phase	Intervention formulation
Methodology		Qualitative	Quantitative	Qualitative
Data collection technique	Evidence synthesis through review of global and national documents, scientific articles, guidelines, etc.	IDI, FGD, KII	Survey	IDI, KII	Intervention design workshops, validation workshop
Study population		IDI and FGD: MSM, MSW, hijra engaged in chemsex KII: DIC service providers, researchers, academicians, programme personnel, policymakers, sexologists, gender specialist and other relevant stakeholders	MSM, MSW and hijra who are aged between 18 and 70 years, and enlisted in the participant list of the selected DICs	IDI: MSM, MSW, hijra engaged in chemsex KII: service providers and stakeholders knowledgeable about chemsex	Relevant stakeholders
Sample size and sampling method (total number of interviews: Qualitative (IDI, KII, FGD): 37–58 Quantitative: 458)		IDI (15-20): maximum variation sampling KII (10-15): intensity sampling FGD (2-3): convenience sampling	Sample size: 458 Sampling: the sample size will be proportionately distributed among MSM/MSW/hijra enlisted at four DICs and selected randomly from the mother list	IDI (5-10): maximum variation sampling KII (5-10): intensity sampling	Intervention design workshops: 4 Validation workshop: 1
Data collection tool		Interview and FGD guidelines	Survey questionnaire	Interview guidelines
Data analysis		Thematic analysis	Univariate, bivariate and multivariate analysis	Thematic analysis
Expected outcome of the phase	Explore the issues related to chemsex and gain in-depth understanding of the chemsex situation Generate and prioritise survey variables		To measure the prevalence of chemsex, reasons for engaging in chemsex and sexual risk behaviour associated with chemsex	Add qualitative depth to survey responses and explore possible explanation Develop chemsex intervention

DIC, drop-in centre; FGD, focus group discussion; IDI, in-depth interviews; KII, key informant interviews; MSM, men who have sex with men; MSW, male sex workers.