HIV-negative MSM1 in Seattle, USA 8,314 participants
HIV incidence (among men who tested HIV negative in past year) (i) Condom use (only protected anal intercourse): 28/1827 clinic visits (1.5%) (ii) Serosorting (UAI2 with HIV negative only): 40/1526 clinic visits (2.6%) (iii) No condom use (nonconcordant UAI): 49/1386 clinic visits (3.5%)
STI incidence (Bacterial STI3: urethral or rectal gonorrhea or chlamydia or early syphilis) (i) Condom use: 601/3859 clinic visits (16%) (ii) Serosorting: 738/3201 clinic visits (23%) (iii) No condom use: 831/3088 clinic visits (27%)
HIV incidence (median followup 3–9 years) (i) Condom use (only protected anal intercourse; data received from authors for only consistent condom users); serosorting (UAI with HIV negative only); no condom use (UAI with some unknown or any HIV positive)
1427 participants Median age: 35 (range: 18–75)
(ii) Serosorting versus condom use: hazard ratio 2.56; 95% CI4 (0.84–7.78) (iii) Serosorting versus no condom use: hazard ratio 0.31; 95% CI (0.16–0.59)
HIV-negative black and Latino MSM in New York, LA, and Philadelphia, USA 724 participants Age not reported
HIV incidence (testing positive during study among those reporting a previous HIV-negative test, most within past year) (i) Condom use (only protected anal intercourse); serosorting (UAI with HIV negative only); No condom use (UAI not limited to HIV negative partners) (ii) Serosorting versus condom use: unadjusted odds ratio 1.68; 95% CI (0.65–4.32) (iii) No condom use versus serosorting: unadjusted odds ratio 2·81; 95% CI (1.30–6.05); adjusted* odds ratio 2.54; 95% CI (1.14–5.68) Adjusted for number of UAI partners of any serostatus, age, education, and employment status
HIV-negative MSM in six cities in the EXPLORE study, USA 4295 participants in EXPLORE study; 2623 participants used for serosorting analyses Age: <30: 42% 31–39: 39% >40: 20%
HIV incidence (i) One-unit increase in the natural log serosorting score (odds of condom use with HIV-positive/unknown partners divided by odds of condom use with HIV negative partners): odds ratio 0.88; 95% CI (0.81–0.95) Adjusted for race/ethnicity, numbers of sexual partners, self-report of sexually transmitted infections, methamphetamine and heavy alcohol use, depression, and use of drug and alcohol during sex
MSM: men who have sex with men. UAI: unprotected anal intercourse. STI: sexually transmitted infection. CI: confidence interval.