1B 3 Injectable Contraception and Acquisition of Chlamydia and Gonorrhea Among South African Women Participating in Mtn-003 (VOICE)

Tuesday, June 10, 2014: 11:05 AM
Lisa Noguchi, MSN, MTN CORE, Microbicide Trials Network, Pittsburgh, PA, Jeanne Marrazzo, MD, MPH, Seattle STD/HIV Prevention Training Center, University of Washington, Seattle, WA, Barbra Richardson, PhD, Department of Biostatistics, University of Washington, Seattle, WA, Sharon Hillier, PhD, Department of Obstetrics & Gynecology, University of Pittsburgh School of Medicine, Pittsburgh, PA, Jennifer Balkus, PhD, MPH, Vaccine and Infectious Disease Division, University of Washington, Seattle, WA, Gita Ramjee, PhD, HIV Prevention Research Unit, South African Medical Research Council, Durban, South Africa, Thesla Palanee, MMed Sci, PhD, Wits Reproductive Health and HIV Institute (WRHI), University of Witswatersrand, Johannesburg, South Africa, Gonasagrie Nair, MB ChB, Centre For The Aids Programme of Research In South Africa, University of KwaZulu Natal, Durban, South Africa, Pearl Selepe, MB ChB, Aurum Institute, Aurum Institute, Klerksdorp, South Africa, Ravindre Panchia, MB ChB, Perinatal HIV Research Unit, Chris Hani Baragwanath Academic Hospital, Soweto, South Africa, Jeanna Piper, MD, Division of AIDS/NIAID, US NIH, Bethesda, MD, Kailazarid Gomez, MPM, Science Facilitation, FHI 360, Durham, NC and Z. Mike Chirenje, MB ChB, Obstetrics & Gynecology, University of Zimbabwe, Harare, Zimbabwe

Background:  The potential impact of injectable hormonal contraception (HC) on C. trachomatis (CT) and N. gonorrhoeae (NG) acquisition in women is unclear. This is the first direct comparison of two commonly used methods of injectable HC in South Africa (depot medroxyprogesterone acetate [DMPA] and norethisterone enanthate [NET-EN]) on acquisition of these infections. 

Methods:  MTN-003 was a randomized trial of HIV chemoprevention in Africa. Women using protocol-defined effective contraception were eligible for enrollment. Testing and treatment for CT and NG occurred at baseline, annual and exit visits, and when clinically indicated. Andersen-Gill proportional hazards models were used to assess the association between injectable contraceptive type and incident CT and NG among 4,077 South African MTN-003 participants. 

Results:  Among the 3,246 (79.6%) participants who used injectable HC during follow-up, DMPA users were more likely, compared to NET-EN users, to be >25 years (43.1% vs. 34.0%, p<0.001), but had similar baseline prevalence of CT (14.3% vs. 14.2%, p=0.95) and NG (3.2% vs. 3.7%, p=0.49). During 3,761 person-years of follow-up, 514 cases of CT (14.2/100 person-years) and 118 of NG (3.1/100 person-years) were observed. Incidence did not differ between current DMPA and NET-EN users for CT (14.1/100 person-years [p-y] vs. 14.5/100 p-y, hazard ratio [HR] 0.95, 95% CI 0.79-1.16) or NG, (3.3/100 p-y vs. 3.8/100 p-y, HR 0.80, 95% CI 0.58-1.09). Adjustment for age, marriage, number of partners and condom use did not modify these inferences (CT: adjusted hazard ratio [aHR] 1.09, 95% CI 0.92-1.29; NG: aHR 0.92, 95% CI 0.64-1.32).

Conclusions:  The risk of incident CT or NG did not differ between DMPA and NET-EN users. Lack of a non-HC comparator prevented estimating risk associated with either injectable method compared to non-use. Women choosing injectable HC should be counseled that risk of these infections does not differ between DMPA and NET-EN use.