Table 1.

SPIRIT diagram for the schedule of enrolment, interventions, and assessments

	Study Period
	Enrolment	Allocation	Post-allocation	Close-out
Timepointb	-t1	0	T0	T1
Enrolment:
Eligibility screen	X
Informed consent	X
Allocation		X
Interventions:
Intervention group			X
Control group			X
Assessments:
Primary outcome and secondary outcomesa	X
Primary outcome and secondary outcomesa				X

^aThe primary outcomes will be self-efficacy in refusing risky sexual behaviours and chemsex. The secondary outcomes will be (i) intention to have chemsex, (ii) actual chemsex behaviours, (iii) condom use consistency in both sober and drug-influenced sex and (iv) having regular HIV/STI testing

^bThe study outcomes will be measured in both groups at baseline (T0) and at 3 months (T1) after baseline