Washington D.C., USA, July 2012www.aids2012.org Equal behaviors, unequal risks: The role of partner transmission potential in racial HIV disparities among men who have sex with men (MSM) in the United States Eli Rosenberg Department of Epidemiology Emory University Rollins School of Public Health Atlanta, GA July 23, 2012 Colleen Kelley, Brandon O'Hara, Paula Frew, John Peterson, Travis Sanchez, Carlos del Rio, Patrick Sullivan Emory University Center for AIDS Research

Washington D.C., USA, July 2012www.aids2012.org HIV prevalence among MSM is high and MSM continue to bear the burden of HIV incidence in the US Black MSM, particularly young black MSM, continue to be overrepresented among new infections Reasons for racial disparity remain unclear Unknown degree to which prevalence of HIV without viral suppression perpetuates incidence disparities Theoretically, greater likelihood of encountering a partner who might transmit HIV translates into increased incidence HIV and MSM

Washington D.C., USA, July 2012www.aids2012.org Measures of transmission risk for disparities research How do we measure an individual’s risk of having unprotected sex in a community? Suggests a measure that incorporates the spectrum of HIV infection, diagnosis, linkage to care, treatment, suppression Our toolkit of measures is limited for this task o HIV prevalence o Community viral load o Population viral load Need for a broad and relevant public health measure

Washington D.C., USA, July 2012www.aids2012.org Proportion of individuals in whole population with a current VL sufficient to transmit HIV A new measure: Transmission Potential Prevalence (TPP) Crosses prevalence with VL measures VL cut-point unknown for MSM. Used conservative estimate of 400 copies/ml.

Washington D.C., USA, July 2012www.aids2012.org What are the TPPs in the black and white MSM communities of Atlanta and how do they relate to HIV risk?

Washington D.C., USA, July 2012www.aids2012.org Study Design Eligibility: > years old, non-Hispanic black or white, had male sex in last 3 months, not in mutually monogamous relationship, reside in metro Atlanta Recruitment: venue-time-space sampling Baseline visit: o HIV testing: Rapid test, WB confirmatory, viral loads o Partnership-level behavioral questionnaire 709 men (399 B, 310 W) enrolled from 7/ /2012 Prospective HIV/STI incidence cohort study of black and white MSM in Atlanta

Washington D.C., USA, July 2012www.aids2012.org Demographics and outcomes Black MSM (n = 399) White MSM (n = 310) p Age, median 25 y28 y<.0001 Education > HS 74 %89 %<.0001 Male partners, prev. 12 mo., median 57.5<.0001 HIV Prevalence 42 %14 %<.0001 HIV Incidence, per 100 PY More details: O’Hara et al TU PE-133 More details: O’Hara et al TU PE-133

Washington D.C., USA, July 2012www.aids2012.org Results: Viral load measures More details: Kelley et al MO PE-264 More details: Kelley et al MO PE-264 Mean log 10 (VL) p VL > 400 copies/ml p A. Community VL Black % 0.93 White1.947 % B. Population VL Black % 0.66 White4.157 % C. Transmission Potential Black n/a 25 % <.0001 White8 %

Washington D.C., USA, July 2012www.aids2012.org Behavioral model

Washington D.C., USA, July 2012www.aids2012.org Results: Behavioral model Probability of having ≥ 1 partner with HIV transmission potential 39% 18%

Washington D.C., USA, July 2012www.aids2012.org Despite similar CVL and PVL, sizeable racial differences in TPP and associated exposure risk Model results suggest limited ability of behavioral interventions alone to eliminate disparities Communities with high TPP should be focus of new resources to prevent transmission HIV surveillance systems can be adapted to include TPP to understand transmission risk in subgroups and make meaningful comparisons Conclusions

Washington D.C., USA, July 2012www.aids2012.org Current VL does not reflect durable virologic suppression Model does not account for other determinants of transmission UAI serosorting not included Does not explain what originally gave rise to disparities Limitations

Washington D.C., USA, July 2012www.aids2012.org Our data support targeting resources to dramatically reduce TPP among black MSM by increasing testing, linkage, and retention in HIV care in order to reduce disparities in HIV incidence, supported by coordinated behavioral interventions to increase effectiveness of treatment. Relevance

Washington D.C., USA, July 2012www.aids2012.org Thank you !! R01-MH R01-HD KL2-RR P30 AI (Emory CFAR) Supported by NIH #: Investigators Recruiters Event staff Retention specialists Data team Our participants! Eli Rosenberg