Sexual relationships, risk behaviour, and condom use in the spread of sexually transmitted infections to heterosexual men.

OBJECTIVE To examine the effect of patient defined non-regular sexual relationships and other risk behaviours on the incidence of sexually transmitted infections in heterosexual men and the role of condom use in the prevention of their spread. DESIGN A prospective cross sectional study of sexual behaviour reported by a standardised self administered questionnaire in new patients who presented for screening and diagnosis. SETTING A genitourinary medicine clinic in west London. SUBJECTS 957 consecutive newly attending heterosexual men who completed a sexual behaviour questionnaire in 1993/94. MAIN OUTCOME MEASURES Variables relating to sociodemographic status, sexual behaviour, condom use, sexually transmitted infections and testing for HIV infection, stratified by the reporting of non-regular partners. RESULTS We found that the 65% of men who reported non-regular sexual partners were more likely to be white collar class (d = 7.5%, 95% CI = 1.3, 13.7) and to have had sexual intercourse with non-United Kingdom born women (d = 7.8%, 95% CI = 3.5, 12.2). They also reported coitarche before 16 years of age (d = 13.4%, 95% CI = 8.0, 18.8) and many more sexual partners both in the last year (d = 13.1%, 95% CI = 10.2, 16.0) and in their lifetime (d = 27.9%, 95% CI = 21.6, 34.2). They were significantly more likely to practise anal intercourse (d = 8.7%, 95% CI = 3.3, 14.1), to smoke (d = 16.3%, 95% CI = 9.8, 22.6), to drink alcohol (d = 4.9%, 95% CI = 1.2, 8.6), and to have chlamydial infection (d = 5.7%, 95% CI = 2.2, 9.2), of which 30% was subclinical. Increasing condom use with regular partners correlated with decreasing incidence of urethral infection (gonorrhoeal and/or chlamydial infection) (p < 0.03) and candidal balanitis (p < 0.03) and a greater likelihood of no infection being detected (p = 0.0002). Use of condoms with non-regular partners was much more frequent than with regular partners (d = 21.4%, 95% CI = 16.7, 26.1). However, we found evidence of oral transmission of urethral gonorrhoea and chlamydial infection among men who reported always using condoms. HIV infection was found in only two men (0.2%), both of whom reported intercourse with non-United Kingdom born women. CONCLUSIONS Heterosexual men who reported non-regular sexual relationships compensated for their increased risk lifestyle by using condoms more frequently and showed only an increased incidence of chlamydial infection. More consistent condom use with regular partners was significantly associated with the absence of sexually transmitted infection. These findings suggest that transmission between regular partners has been underestimated.