Methods	DESIGN: RCT; number of centres not reported.
	LENGTH OF FOLLOW-UP: 3 and 12 months.
	DATA ANALYSIS: Not reported in detail. Appears to be based only on the participants who completed each follow up
	ATTRITION RATE: Attrition reported in Table 2 is based on 337 participants at baseline; attrition reported in the text is based on 400 participants at baseline. The attrition data given here were extracted from Table 2:
	Completed 3 month follow up: Group 1=49/84 (58%); Group 2=59/81 (73%); Group 3=56/88 (64%); Group 4=49/84 (58%)
	Completed 12 month followup: Group 1 = 50/84 (60%); Group 2=50/81 (62%); Group 3=36/88 (41%); Group 4=51/84 (61%)
	UNIT OF DATA ANALYSIS: Individuals.
	SAMPLE SIZE CALCULATION: Not reported.
	EQUIVALENT STUDY GROUPS AT BASELINE: Reported only that the study groups did not differ significantly on ethnicity (P = 0.42), age (P = 0.22) and condom use at last vaginal intercourse with main partner (P = 0.92)
	PROCESS EVALUATION: Not reported.
Participants	NUMBER RANDOMISED: Not reported. Stated that 400 participants were recruited; however, the data presented indicate that there were 337 participants in total in the study groups at baseline
	AGE: Not reported separately by study group. Overall mean =18 years (range 15 to 21)
	SOCIO-ECONOMIC STATUS: Not reported.
	ETHINCITY/RACE: Not reported separately by study group. Overall, Latina=55%;
	Black=45%
	LOCATION: USA; New York City. PREVIOUS STI: Not reported separately by study group. Overall, 25% had had an STI
	SEXUAL RISK BEHAVIOUR: Not reported separately by study group. Overall, 58% had used a condom at last vaginal intercourse with a casual partner; 47% had used a condom at last vaginal intercourse with their main partner; 35% had engaged in anal intercourse; 47% had a history of pregnancy
Interventions	GROUP 1: HIV risk-reduction counselling and video (n randomised not stated; n = 84 at baseline)
	YEAR STARTED: Not reported.
	PROVIDER(S): Trained clinic staff (health care assistants).
	SETTING(S): Not explicitly stated; appears to be family planning clinic(s)
	TYPE: Information/education and practical skills development: Participants received the Group 3 intervention (video) followed by the Group 2 intervention (counselling)
	DURATION: Not reported. Minimum duration would be 36 to 41 minutes (i.e 21 minutes of video and 15 to 20 minutes of counselling)
	THEORETICAL BASIS: The interventions were informed by Social Cognitive Theory; the Theory of Reasoned Action; and the Health Belief Model (not stated explicitly whether these three theoretical models were all applicable to all the interventions)
	STIs COVERED: Mainly about HIV but appears to cover STIs in general
	GROUP 2: HIV risk reduction counselling (n randomised not stated; n = 81 at baseline)
	YEAR STARTED: Not reported.
	PROVIDER(S): Not stated; appears to be as Group 1.
	SETTING(S): As Group 1.
	TYPE: Information/education (details not reported) and practical skills development for sexual risk reduction (few details given). One-to-one counselling based on the protocol of project RESPECT but omitting the HIV testing component
	DURATION: Single session, 15 to 20 minutes.
	THEORETICAL BASIS: As Group 1.
	STIs COVERED: As Group 1.
	GROUP 3: HIV risk reduction video (n randomised not stated; n = 88 at baseline)
	YEAR STARTED: Not reported.
	PROVIDER(S): Mainly self-directed by participants (watching a video) with some contact with a research assistant
	SETTING(S): As Group 1.
	TYPE: Video watched by participants individually, providing information/education about HIV and condom use. Appears to involve some practical skills development, as encourages cognitive restructuring or rehearsal
	DURATION: 21 minutes.
	THEORETICAL BASIS: As Group 1.
	STIs COVERED: AS Group 1.
	GROUP 4: Usual care (n randomised not stated; n = 84 at baseline)
	YEAR STARTED: Not reported.
	PROVIDER(S): Not reported.
	SETTING(S): Not reported (assumed to be family planning clinics)
	TYPE: Reported only as usual care, with no details provided; unclear what ‘usual care’ refers to, e.g. whether STI prevention or family planning
	DURATION: Not reported (usual care).
	THEORETICAL BASIS: Not applicable (usual care).
	STIs COVERED: Not reported.
Outcomes	PRIMARY (stated as the ‘main’ outcome):
	Condom use at last vaginal intercourse with main partner.
	SECONDARY (stated as ‘other’ outcomes but results not reported):
	Self-reported recurrent STIs; positive chlamydia tests;
	Number of casual sex partners;
	HIV risk beliefs; self-efficacy for condom use (6-point scale);
	The following were included in follow up questionnaires (not formally stated as outcomes): Types of intercourse (vaginal, oral, anal); types of main partners (main, casual, new); number of unprotected sex acts with each partner type
Notes	COST DATA: Stated only that the Group 1 intervention is inexpensive (cost of video = approximately $30); and that participants were paid $30 for their participation, $40 for the 3-month follow up and $50 for the 12-month follow up
	As baseline assessment may affect outcomes, to evaluate the independent and joint contributions of baseline assessment and intervention on the outcomes being measured, 70% of the participants were randomised to receive the baseline questionnaire and 30% were randomised to get no baseline questionnaire. Reported in the results that having had a baseline assessment did not affect outcomes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Adequate sequence generation?	Unclear risk	No information provided.
Allocation concealment?	Unclear risk	No information provided.
Blinding? All outcomes	Unclear risk	No information provided.
Incomplete outcome data addressed? All outcomes	High risk	A 12 month follow up, Group 3 lost more participants than the other groups (based on findings of a Chi-square test; not reported). No reasons given for attrition
Free of selective reporting?	Unclear risk	Most outcomes were only introduced in the results section. The outcomes alluded to in follow up questionnaires (types of intercourse; types of main partners; number of sex acts with each partner type) were not reported except for main partners). Quantitative data were only reported consistently for the main outcome. For other outcomes, data were either not reported at all or were described narratively, with some illustrative reporting of p-values
Free of other bias?	Unclear risk	Unclear