Risk Factors for Sexually Transmitted Infections and HIV in Men who have Sex with Men: Examination of a PSA Biomarker, Sexual Behaviors, and the Role of Body Image

Introduction: Human immunodeficiency virus (HIV) and other sexually transmitted infections (STIs) are significant public health problems. While these diseases are associated with detrimental health outcomes in many populations, no group is more affected than men who have sex with men (MSM). Despite this, significant gaps exist in the understanding of the increased incidence of infection in this population. We examined three distinct topics that would make substantial contributions to the HIV/STI prevention among MSM literature. First, research related to HIV/STI transmission from sexual intercourse in MSM has relied on self-reports of sexual activity, which is flawed because participants may misreport behavior. A biological marker of semen exposure in rectal swabs, indicative of unprotected receptive anal intercourse (uRAI), would reduce or eliminate researchers' reliance on self-reported behavior. Second, little is known about the spectrum of sexual behaviors being practiced within the MSM community. Because of the paucity of information on the prevalence of specific sexual practices, even less is known about the risks associated with these behaviors. Third, preliminary information suggests that MSM with negative or positive body image, compared to MSM with moderate body image, may be more likely to engage in risky sexual behaviors. No prior study has examined the direct association between body image and STI in MSM.;Methods: We conducted a cross-sectional study of MSM (N=235) recruited from the Sexual Health Clinic (SHC) at an urban health department. Clinical and behavioral data were collected from each participant. For the first aim (n=54), we quantified PSA from rectal swabs collected from MSM and compared PSA results to self-reports of unprotected RAI. For the second aim (n=231), we used data from the self-administered behavioral survey to calculate the prevalence of specific sexual behaviors and substance use in the past three months and over a man's lifetime. We used modified Poisson regression to evaluate the association between one of these behaviors, group sex, and prevalent STI. To address the third aim, participants self-administered the Male Body Attitudes Scale (MBAS) to assess body image. We used modified Poisson regression to assess whether body image is associated with prevalent STI.;Results: In our first analysis, only one (2%) rectal swab was PSA-positive and it was collected from a man who reported no uRAI in the 72 hours preceding swab collection. In our second analysis, participation in group sex in the past three months was associated with a more than two-fold (adjusted prevalence ratio (APR): 2.11, 95% confidence interval (CI): 1.13, 3.95) increased prevalence of gonorrhea, but not with chlamydia, after adjustment for race, age, and drug use. Our third analysis revealed no significant association between body image and prevalent STI in unadjusted or adjusted models (APR: 1.17; 95% CI: 0.89, 1.53).;Conclusions: Using current methods, PSA is not likely to a suitable biomarker of unprotected RAI among MSM. Group sex, which previously has been linked to risky behaviors, is strongly associated with increased prevalence of gonorrhea. Our findings suggest that group sex may act as a source of disease transmission and may be an important behavior for HIV/STI prevention messages to address. Our findings indicate that body image may not directly affect disease prevalence in MSM and may not be an appropriate target for STI prevention programs among MSM.