[1] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Infect Dis & Microbiol, POB 7319, Pittsburgh, PA 15213 USA
[2] Univ Pittsburgh, Grad Sch Publ Hlth, Ctr LGBT Hlth Res, Pittsburgh, PA USA
[3] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Behav & Community Hlth Sci, Pittsburgh, PA USA
[4] Univ Connecticut, Dept Human Dev & Family Studies, Hartford, CT 06112 USA
[5] Univ Maryland, Sch Publ Hlth, Dept Epidemiol & Biostat, College Pk, MD 20742 USA
[6] RAND Corp, Pittsburgh, PA USA