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O18.2 Injectable progestin contraception and acquisition of hsv-2 infection among south african women participating in the voice trial
  1. LM Noguchi1,
  2. SL Hillier2,
  3. BA Richardson3,
  4. ZM Chirenje4,
  5. JE Balkus3,
  6. JM Piper5,
  7. JM Marrazzo6
  1. 1Johns Hopkins University
  2. 2University of Pittsburgh
  3. 3SCHARP/FHCRC/University of Washington
  4. 4UZ-UCSF
  5. 5US NIH/NIAID/DAIDS
  6. 6University of Washington

Abstract

Introduction Observational data suggest HIV-1 acquisition differs between users of two common injectable progestin-only contraceptives (IPC), depot medroxyprogesterone acetate (DMPA) and norethisterone enanthate (NET-EN). Data are limited on the potential impact of both IPC types on herpes simplex virus type 2 (HSV-2) acquisition.

Methods We conducted a secondary analysis among IPC users enrolled at South African sites in VOICE, a multi-centre randomised trial of topical and oral HIV-1 chemoprophylaxis. Contraceptive use assessment was conducted monthly. HSV-2 was diagnosed by Focus HerpeSelect EIA at enrollment and repeat EIA at study exit in all participants (seroconversion cutoff value ≥3.5); quarterly EIA was available for a subset to assess seroconversion timing. Using Cox proportional hazards regression, we assessed the association between IPC type and HSV-2 acquisition with adjustment for potential confounders (age, marriage/cohabitation, education, condom use, number of partners, VOICE study arm).

Results Among 1776 IPC users who were HSV-2-seronegative at enrollment, 922 (51.9%) used DMPA, 716 (40.3%) used NET-EN, and 138 (7.8%) used both IPC types at different times during follow-up. Among the 1638 IPC users who did not switch IPC type during follow-up, 1506 (91.9%) had baseline and exit HSV-2 serology available. Over 1534.1 person-years (py) of follow-up, 178 incident HSV-2 cases occurred: 107 in DMPA users (crude incidence rate [IR] 11.3/100 py) and 71 in NET-EN users (crude IR 12.1/100 py). Among 640 participants with quarterly HSV-2 serology, 45 cases occurred among DMPA users over 350.4 py and 31 among NET-EN users over 231.1 py (HR = 0.97; 95% CI 0.61–1.53; aHR = 1.02; 95% CI 0.64–1.62).

Conclusion HSV-2 risk did not differ by DMPA versus NET-EN use. These results are consistent with our findings that DMPA users in VOICE did not have higher risk of genital tract infection (gonorrhoea, chlamydia or trichomoniasis) compared to NET-EN users, despite having higher risk for HIV-1 infection.

Disclosure of interest statement The authors report no conflicts of interest.

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