Ten intervention studies (n=9,222) were included: two were randomised at individual levels; four cluster-randomised at school levels; three non-randomised studies at school level; and one non-randomised study at individual level. Details of the methodological quality of individual studies according to the pre-specified scoring system were not given. The number of participants in individual studies ranged from 315 to 2,026. Attrition rates ranged from 3.8 per cent to 38.2 per cent. Follow-up assessments ranged from immediately after the intervention to 12 months.
Outcomes related to knowledge and attitude
The included studies evaluated one or more of the pre-specified outcomes. Compared with the control group, almost all studies that evaluated these outcomes showed that the intervention group reported a desired effect. For example, in relation to knowledge and attitudes regarding HIV, STI, and abstinence, use of condoms, knowledge and attitudes to AIDS, and attitudes to persons living with HIV/AIDS.
Outcomes related to behavioural intention
Two studies showed significant desired effect regarding abstinence. In one study, a significantly greater percentage of the control group reported intentions to abstain than intervention group. Two studies showed a desired effect on the intention to use condoms in the intervention group. In another study, the positive effect of intervention had diminished over a six-month follow up period.
Outcomes related to actual behaviour change
There was no difference between the groups regarding the actual use of condoms in all five studies reporting on this outcome. Three out of four studies showed no significant increase in the reported practice of abstinence in the intervention group. Two studies reported positive effect on the number of sexual partners in the intervention group. One study reported improved communication with new sexual partners among the intervention group at six-month evaluation, but this effect had diminished at the 12-month follow up.
Some studies found that interventions improved general communication skills and were more acceptable if portrayed as HIV or STI prevention strategies rather than sex education.