Methods	DESIGN: Single centre RCT
	LENGTH OF FOLLOW-UP: Immediately post-intervention and 2 months after intervention
	DATA ANALYSIS: Used an intention to treat analysis with last observations carried forward in lieu of missing data
	ATTRITION RATE: Not reported separately by group. Overall 70/78 participants attended the immediate post-intervention test (90%) and 67/78 participants completed 2 month follow up (86%)
	UNIT OF DATA ANALYSIS: Individuals; same as the unit of randomisation
	SAMPLE SIZE CALCULATION: Stated that power analyses using effect sizes from earlier work (reference provided) indicated that a sample size of 17 per group would provide ‘good’ (i.e. β > 0.80) power
	EQUIVALENT STUDY GROUPS AT BASELINE: Stated that the only difference between groups found was on decisional balance, where Group 3 scored higher (mean = 13.58) than Group 1 (mean = 12.91) and Group 2 (mean = 10.89); P = 0.05
	Stated that, of 31 participants who reported exposure to other STD programmes (e.g. television), there were no differences between groups 1 and 2 (P = 0.21) or between groups 1 and 3 (P = 0.80)
	PROCESS EVALUATION: A 7-item group experience measure assessed participants’ perceptions of the session delivery and their comfort and enjoyment of the group (data presented but not extracted)
Participants	NUMBER RANDOMISED: 78
	AGE: Not reported separately by group. Overall mean = 20 years
	SOCIO-ECONOMIC STATUS: Not reported.
	ETHINCITY/RACE: Not reported separately by group. Overall 76% of participants were European-American
	LOCATION: USA; Syracuse, New York.
	PREVIOUS STI: Stated that only a small proportion of women reported a recent STD (no further details provided)
	SEXUAL RISK BEHAVIOUR: Not reported separately by group. Women had to be sexually active during the previous 2 months for inclusion in the trial, but were excluded if they used condoms at every episode of vaginal, oral and anal sex during the previous 2 months or if pregnant or trying to become pregnant. Overall, 48% reported ≥ 3 lifetime sexual partners; 65% reported unprotected vaginal sex in the previous 2 months; and 53% were in committed relationships and not using condoms
	OTHER: Participants were those who volunteered for a study of ‘College Women’s Health’ for either partial fulfilment of course requirements or for extra credit in undergraduate psychology courses (suggests the population was limited to psychology undergraduates)
Interventions	GROUP 1: Information-Motivation-Behavioural skills (1MB) group with motivational enhancement (n randomised not reported)
	YEAR STARTED: Not reported.
	PROVIDER(S): Two facilitators who were advanced graduate students in clinical psychology with training in sexual health
	SETTING(S): Not explicitly stated but appears to be a university health and behaviour centre
	TYPE: Small-group intervention with approximately 8 participants per group in which sexual risk reduction was normative and supported and the threat of STIs and promotion of behaviour change was personalised. Comprised information/education about STI transmission, consequences, prevention and treatment. Also included practical skills development, based on sexual communication role playing, with a focus on assertive-ness skills. Facilitators followed detailed manuals to protect against facilitator drift and contamination of intervention components
	DURATION: One session lasting 150 minutes conducted 1 week after the baseline survey. The session was divided into six consecutive segments, of duration 10, 30, 20, 45,15 and 30 minutes, for each of which a detailed description is provided (information not extracted)
	THEORETICAL BASIS: Based on the Information-Motivation-Behavioural skills model (IMB) strengthened with a motivational enhancement approach to personalise the threat of STIs and promote behaviour change
	STIs COVERED: STIs in general.
	GROUP 2: Time-matched information provision group (INFO) (n randomised not reported)
	YEAR STARTED: Not reported.
	PROVIDER(S): As Group 1.
	SETTING(S): As Group 1.
	TYPE: Structured as Group 1 but based on information provision only (information/ education about STI transmission, consequences, prevention and treatment). Facilitators avoided personalising the threat of STIs
	DURATION: As Group 1.
	THEORETICAL BASIS: None specified; information provision only
	STIs COVERED: As Group 1.
	GROUP 3: Waiting list control group (n randomised not reported)
	Received an intervention identical to Group 2, but this occurred after Group 3’s follow-up survey
Outcomes	(Not stated which were primary):
	Knowledge: about STI transmission, consequences, prevention and treatment;
	Attitudes towards condoms and perceptions of sexual risk (assessed with 3 instruments);
	Behavioural intentions (based on an 8-item instrument);
	Behavioural skills: sexual assertiveness scores;
	Self-reported sexual behaviour: vaginal sex without condom; vaginal sex with condom; oral sex without condom; oral sex with condom; number of sexual partners
Notes	COST DATA: None reported.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Stated only that participants were assigned randomly, with no explanation of the method used
Allocation concealment?	Unclear risk	Stated that participants generated code names to ensure confidentiality and reduce error from self-presentation bias. However, it is unclear whether this would have resulted in allocation concealment
Blinding? All outcomes	Unclear risk	Stated that immediately post-intervention the survey was administered by a research assistant who was not present at the groups and who was masked to the study condition. But not stated whether the research assistants who administered the 2 month follow up survey were also blinded
Incomplete outcome data addressed? All outcomes	Unclear risk	An intent to treat analysis was used, with last observations carried forward to account for missing data. Stated that the 67 completers at 2 month follow up did not differ from the dropouts (n = 11) as a function of group assignment (P = 0.44) and that no differences were found on the dependent measures between the completers and dropouts
		Note however that attrition was not reported separately by study group and no reasons were given for attrition
Free of selective reporting?	Low risk	All outcomes mentioned in the methods section were reported in the results section
Free of other bias?	Unclear risk	Unclear