Factors associated with concurrent sexual partnerships among men who have sex with men (MSM) Kyle T. Bernstein, Katherine Ahrens, Susan S. Philip, Jeffrey D. Klausner STD Prevention and Control Services San Francisco Department of Public Health

Concurrency Having two or more sex partners that overlap in time Mathematical models suggest concurrency may be an important factors in creating and maintaining epidemic STD transmission within sexual networks

Concurrency as an individual risk factor Nearly all empiric studies in heterosexual populations Some report increased risk for STDs, while others show no increased risk Few studies conducted among MSM

Objectives To examine the relationship between concurrency and STDs Is concurrency associated with an STD diagnosis? Are other demographic/behavioral risk factors associated with concurrency?

Methods Between June - August, 2007, MSM seeking services at SF City Clinic were asked to complete a survey: How many men did you have anal sex with in the last 6 months? If more than one: Have you had anal sex with the same person more than once in the past 6 months? If ‘Yes,’ Have you had anal sex with anyone else between those fucks (for example, did you have sex with “Joe” and then “Sam” and then “Joe” again)?

Methods Survey data linked to clinic records Demographics Condom Use Number of Sex Partners HIV Serosorting Any unprotected sex partners by their HIV status (3 mo) Patient HIV status HIV Status Drug Use STD Diagnosis (GC, CT, Syphilis) At visit 6 months prior to visit Obtained from clinic record, not self-report

Statistical Analysis Univariate Multivariate χ2 and Wilcoxon Rank Sum Logistic regression Adjusted Odds Ratios, 95% Confidence Limits

Participants Prevalence of concurrency = 183/468=39.1% 468 MSM completed survey <2 sex partners (n=156) 2+ sex partners (N=312) Concurrent Partnerships (n=183) No Concurrent Partnerships (n=129) Prevalence of concurrency = 183/468=39.1%

Univariate Results CP n=183 No CP n=129 P-value Median Age, years 35 34 0.791 White Race 67.8% 51.9% 0.034 Gay 89.1% 81.4% 0.055 Median # Male Sex Part* 4.5 3.0 0.014 HIV-infected 31.2% 18.6% 0.013 Serosorting 39.3% 24.8% 0.007 * In the past 3 months

Univariate Results P-value CP n=183 No CP n=129 Drug Use (3 months) Alcohol 12.0% 2.3% 0.002 Meth 30.1% 35.7% 0.297 Popper 6.0% 1.6% 0.052 STDs (current or past 6 months) CT 14.8% 11.6% 0.426 GC 14.2% 16.6% 0.614 PS syphilis 3.8% 0.237

Multivariate Results OR 95% CI White Race (vs. non-white) 1.80 1.10-4.10 Alcohol Use 5.35 1.53-18.65 Number of Male Sex Partners 1.36 1.12-1.64 Serosorting 2.38 1.39-4.10 Current or prior STDs and HIV status were not associated with concurrency

Mantra: Concurrency is bad…. but for whom Network Individual

Limitations One measure of concurrency Cross-sectional data STD clinic population in SF May be of limited generalizibility

Summary Among a clinic-based population of MSM, concurrency was associated with being White, using alcohol, practicing serosorting, and having a larger number of sex partners Concurrency was not associated with GC, CT, syphilis, or HIV infection

Conclusions Concurrency may be important at the network level Increases “speed” at which an STD moves through a network Concurrency may have less of an impact on individual risk

Acknowledgments SF DPH CA DPH Robert Kohn, Ken Katz Deborah Williams, Tochia Brewster, Serlina Cheung, Wendy Ho, Amalia Jarquin CA DPH Dan Wohlfeiler, Julia Marcus

Additional Slides

What is the role of concurrency in individual STD risk? Concurrent Partnerships STD More Sex Partners