Contribution of Anal Sex to HIV Prevalence Among Heterosexuals: A Modeling Analysis
Anal intercourse is reported by many heterosexuals, and evidence suggests that its practice may be increasing. We estimated the proportion of the HIV burden attributable to anal sex in 2015 among heterosexual women and men in the United States. The HIV Optimization and Prevention Economics model was developed using parameter inputs from the literature for the sexually active U.S. population aged 13–64. The model uses differential equations to represent the progression of the population between compartments defined by HIV disease status and continuum-of-care stages from 2007 to 2015. For heterosexual women of all ages (who do not inject drugs), almost 28% of infections were associated with anal sex, whereas for women aged 18–34, nearly 40% of HIV infections were associated with anal sex. For heterosexual men, 20% of HIV infections were associated with insertive anal sex with women. Sensitivity analyses showed that varying any of 63 inputs by ±20% resulted in no more than a 13% change in the projected number of heterosexual infections in 2015, including those attributed to anal sex. Despite uncertainties in model inputs, a substantial portion of the HIV burden among heterosexuals appears to be attributable to anal sex. Providing information about the relative risk of anal sex compared with vaginal sex may help reduce HIV incidence in heterosexuals.
KeywordsHIV Heterosexual Anal intercourse
The findings and conclusions in this report are those of the authors and do not represent official views of the Centers for Disease Control and Prevention. The authors wish to acknowledge the contributions of Marie-Claude Boily and Michael Pickles by sharing relevant research on heterosexual anal sex and providing consulting advice on the calibration of the U.S. National HIV Model used for analyses. They also wish to acknowledge Emily L. Tucker and Christopher Goodrich for implementing the programming to make this analysis possible.
This research was supported by the Centers for Disease Control and Prevention, Division of HIV/AIDS Prevention, Contract No. 200-2012-53603 (Tasks 5 and 6).
Compliance with Ethical Standards
Conflicts of interest
The authors have no conflicts of interest or financial relationships to disclose.
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