title: A Data-Driven Simulation of HIV Spread Among Young Men Who Have Sex With Men: Role of Age and Race Mixing and STIs.
abstract: OBJECTIVE
  Young men who have sex with men (YMSM) in the United States have a high HIV incidence with substantial racial disparities that are poorly understood. We use a data-driven simulation model to understand the impact of network-level mechanisms and sexually transmitted infections on the spread of HIV among YMSM.
  
  
  METHODS
  We designed and parameterized a stochastic agent-based network simulation model using results of a longitudinal cohort study of YMSM in Chicago. Within this model, YMSM formed and dissolved partnerships over time, and partnership types were stratified by length of partnership, sex, and age of the partner. In each partnership, HIV, gonorrhea, and chlamydia could be transmitted. Counterfactual scenarios were run to examine drivers of HIV.
  
  
  RESULTS
  Over a 15-year simulation, the HIV epidemic among YMSM continued to rise, with Latino/white YMSM facing a steeper increase in the HIV burden compared with black YMSM. YMSM in partnerships with older MSM, in particular black YMSM with older black MSM, were at highest risk for HIV, and 1 infection prevented with an older partner would prevent 0.8 additional infections among YMSM. Additionally, racial disparities in HIV were driven by differences in the HIV prevalence of YMSM partners. Finally, of all HIV infections among YMSM, 14.6% were attributable to NG and CT infections.
  
  
  CONCLUSIONS
  Network-level mechanisms and sexually transmitted infections play a significant role in the spread of HIV and in racial disparities among YMSM. HIV prevention efforts should target YMSM across race, and interventions focusing on YMSM partnerships with older MSM might be highly effective.
authors.affiliation: *Department of Industrial Engineering and Management Science, Northwestern University McCormick School of Engineering, Evanston, IL; and †Department of Medical Social Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Ekkehard C
authors.initials: EC
authors.lastname: Beck
authors.forename: Michelle
authors.initials: M
authors.lastname: Birkett
authors.forename: Benjamin
authors.initials: B
authors.lastname: Armbruster
authors.forename: Brian
authors.initials: B
authors.lastname: Mustanski
mesh_terms: D000375:Aging; D003198:Computer Simulation; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology / Q000635:transmission*; D018451:Homosexuality, Male; D006801:Humans; D015994:Incidence; D008297:Male; D008954:Models, Biological; D015995:Prevalence; D044469:Racial Groups; D012747:Sexual Partners; D013997:Time Factors; D055815:Young Adult