Men who have sex with men (MSM) account for a large subgroup of sexually transmitted infections (STIs) in the USA1 2 and STI incidence has increased in this population during the past decade.3 4 Substance use is linked to STIs among MSM;5^–7 however, more information is needed about recent STIs (and associated factors) among MSM substance users. Sexual event-level information could help guide risk-reduction efforts for a very high-risk population that is likely to be fuelling HIV and STI transmission in the USA. The present analysis addresses STIs reported in a multi-city study of sexually risky MSM who use substances.

METHODS

MSM aged 18 years or older who reported (a) alcohol or drug use in the context of anal sex and (b) unprotected anal sex with a non-primary partner, both in the past 6 months, were eligible. A convenience sample was recruited in 2005–6 through staff outreach (for example, bars, agencies, street), flyers and ads, and word-of-mouth for residents in four cities in the USA: Chicago, Los Angeles, New York and San Francisco.

An audio/computer-based behavioural assessment was self-administered to collect data. On the assessment, HIV status and alcohol or drug (marijuana, methamphetamine, crack, cocaine, poppers, Viagra and other drugs) use during participants’ most recent anal sex encounter with a non-primary male partner was self-reported, as were demographic variables (age, race/ethnicity, education level, US or non-US born, sexual orientation, city). STIs in the past year were assessed with the following item:

Please indicate if you have had any of the following sexually transmitted diseases (STDs) in the past 12 months (check all that apply): chlamydia; gonorrhoea; syphilis; urethritis (a burning or discharge from the penis); other; had a STD but don’t know the name; none.

Bivariate and multivariate logistic regression analyses tested associations of demographic characteristics and recent anal sex-linked substance use with reported STIs. Multivariate regression models consisted of simultaneous entry of all variables in their association with each of the dependent variables: any STI, gonorrhoea, syphilis, chlamydia, urethritis and other/undetermined STI.

RESULTS

The sample (n = 1540) was diverse: less than 40% identified as white; nearly half reported being HIV positive; more than a quarter were 18–29 years old; and there was an even distribution across the three education level groups (table 1). A third (33%) indicated they had an STI in the past 12 months, including 13% gonorrhoea, 11% syphilis, 8% chlamydia, 5% urethritis, 10% other or unidentified infection (not in table). Less than half (44%) of the men reported having a primary partner (that is, a man they lived with or saw a lot and to whom they felt a special emotional commitment for at least 3 months) and nearly all (94%) reported having a non-primary sex partner, each within the past 3 months.

Bivariate analysis (table 1) found HIV positive status, drug use during recent anal sex and multi-substance use during recent anal sex to be associated (p<0.05) with having a recent STI; anal sex-linked alcohol use was inversely associated (p<0.05) with recent STI.

In multivariate analysis (table 1), men who were HIV positive were more likely than others to report having any recent STI, including gonorrhoea (p<0.05); men who were HIV positive were four times as likely (p<0.05) to report syphilis. Men aged 18–29 years old compared with those 40 years or older were more likely (p<0.05) to report any recent STI as well as gonorrhoea specifically and other/undetermined infection. Men who used drugs other than alcohol during recent anal sex were more likely (p<0.05) to report any recent STI, syphilis and other STIs; men who used alcohol were less likely (p<0.05) to report having recent STIs and syphilis. Black men compared with white men were more likely to report syphilis infection and less likely to report chlamydia infection (p<0.05). Participants born in the USA were less likely (p<0.05) to report another or unidentified STI compared with participants born elsewhere. Alcohol and drug use during sex and demographic factors were not associated with urethritis in this analysis.

CONCLUSIONS

STIs in the past year are common among sexually active and risky MSM who use substances: a population that is likely to be fuelling HIV and other STI transmission in the USA. HIV and other STI infection rates may continue to rise due to, among other potential factors, effective retroviral medications and decreased perceived severity of HIV, as seen in the past decade.8 9 Several factors associated with STIs in this sample may suggest targeted interventions.

The study is limited to convenience sampling of residents in four cities in the USA; however, we reached a demographically diverse sample of MSM for analytic representation. The data have a common limitation of self-report, including STI data; however, steps were taken to maximise accuracy (for example, audio/computer self-assessment). Behavioural windows of recent STIs (past 12 months, which is limited in that it could represent incident or prevalent infections) and substance use during anal sex (that is, most recent encounter) are not directly linked; however, it is difficult to link 1-year STIs with a pinpointed encounter in that time period. Because past behaviour predicts future behaviour,10 recent (3 month) encounter-specific alcohol and drug use in the context of anal sex behaviour is a reasonable estimate of overall 12 month risk behaviour across the sample. Analysis on encounter-specific behaviour also affords detangling multi-substance use in the context of anal sex, which is not easily allowable with broader windows of behaviour.

Given the high-risk nature of this sample (that is, men who had unprotected anal sex and had anal sex while drunk or high in the past 6 months), it is particularly important from a public health standpoint to determine what factors are associated with STIs. Improved and targeted risk reduction interventions are needed for this group overall. In addition, within this risky group, men who are HIV positive, younger, born outside the USA and used drugs (not alcohol) in the context of anal sex could particularly benefit. Further need for addressing syphilis among black men and chlamydia among white men, specifically, is evident here. More research is needed to replicate findings and to identify best approaches to successfully reduce sexual risk behaviour among high-risk MSM who use alcohol and other drugs during sex.