Individual characteristics are less important than event characteristics in predicting protected and unprotected anal intercourse among homosexual and bisexual men in Melbourne, Australia

OBJECTIVE: To describe individual, social network and encounter specific factors associated with protected anal intercourse (PAI) and unprotected anal intercourse (UAI). METHODS: This was a cross sectional survey conducted between April and November 2002. A total of 733 sexual encounters were reported by 202 men recruited from the gay community in Melbourne, Australia. Predictors of self reported PAI and UAI were examined. RESULTS: Of the 733 sexual events most (56.3%) did not involve anal intercourse, and more involved PAI than UAI (30.6% versus 13.1%). PAI was more likely than no anal intercourse (NAI) if the participant's social network was mostly homosexual, the partner was an occasional or casual partner, or was HIV positive. PAI was less likely if sex took place at a "beat" but more likely if it took place at a sauna. PAI was more likely if the partner was affected by drugs or alcohol. UAI was more likely than NAI if the participant had injected drugs in the year before interview. It was less likely if the partner was occasional or casual or was HIV positive but more likely if the partner's HIV status was unknown. UAI was much more likely than NAI if the encounter took place at a "sex on premises" venue. CONCLUSIONS: In this analysis it is the characteristics of the sexual encounter that predict whether PAI or UAI rather than NAI takes place.