Heterosexual behaviour, risk factors and sexually transmitted infections among self-classified homosexual and bisexual men

Our study of men presenting at a genitourinary medicine clinic shows that self-classification into homosexual or bisexual does not accurately define behaviour. We found that 8.5% of self-defined homosexual men had had heterosexual intercourse in the past year and that 26% of self-defined bisexual men had not. Overall, 19% of homosexual/bisexual men reported vaginal intercourse in the past year and a further 42% in their lifetime. Compared with heterosexual men attending our clinic, the practising bisexual men were significantly more likely to come from a white ethnic group (P<0.003) and to use condoms invariably with regular female partners (P=0.0001). There was no significant difference in consent for HIV testing between homosexual (43%), practising bisexual (49%) and heterosexual (42%) men despite significantly different perceptions of risk. None of the practising bisexual men was seropositive for HIV infection (P=0.06) or for syphilis (P=0.02), or had chlamydial infection, which was found infrequently among homosexual men in general (P=0.00001). HIV infection found in 19.4% of the exclusively homosexual men was associated with more frequent alcohol consumption (P=0.06).