Per-partner condom effectiveness against HIV for men who have sex with menJohnson, Wayne D.; O’Leary, Ann; Flores, Stephen A.AIDS: July 17, 2018 - Volume 32 - Issue 11 - p 1499–1505 doi: 10.1097/QAD.0000000000001832 Epidemiology and Social Abstract Author InformationAuthors Article MetricsMetrics Objective: Few studies have examined condom effectiveness for HIV prevention among MSM. We estimated condom effectiveness per partner in four cohorts of MSM during 1993–2003 (JumpStart, Vaccine Preparedness Study, VAX004 and Project Explore). Methods: We used logistic regression to estimate the increase in odds of new HIV infection per HIV-positive partner for condom-protected receptive anal intercourse (PRAI; partners with whom condoms were always used) and condomless (unprotected) receptive anal intercourse (URAI; partners with whom condoms were sometimes or never used). To estimate condom effectiveness for preventing HIV transmission, we applied the concept of excess odds, the odds ratio minus 1. The condom failure rate was estimated as the excess odds per PRAI partner divided by the excess odds per URAI partner. Condom effectiveness was then 1 minus the failure rate. Results: The excess odds of HIV infection per HIV-positive partner were 83% for URAI and 7% for PRAI. The resulting failure rate (9%) indicated per-partner condom effectiveness of 91% (95% confidence interval 69–101). Conclusion: The increase in odds of new HIV infection per HIV-positive partner for receptive anal intercourse was reduced by 91% for each partner with whom condoms were always used. Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. Correspondence to Wayne D. Johnson, PhD, MSPH, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, 1600 Clifton Rd MS-37, Atlanta, GA 30333, USA. Tel: +1 404 639 1932; fax: +1 404 639 1950; e-mail: firstname.lastname@example.org Received 9 December, 2017 Revised 2 April, 2018 Accepted 10 April, 2018 Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website (http://www.AIDSonline.com). Copyright © 2018 Wolters Kluwer Health, Inc.