June 03, 2015
1 min read

HIV-1 acquisition risk lower among users of NET-EN vs. DMPA

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Norethisterone enanthate may be a lower HIV-risk option for injectable progestin contraception compared with the more commonly used depot medroxyprogesterone acetate, according to recently published data.

Researchers evaluated prospective data on 3,141 South African women enrolled in the VOICE trial, a randomized, placebo-controlled study of tenofovir for HIV-1 prevention in women. Participants were HIV uninfected, sexually active, not pregnant and without genitourinary infection. The women underwent monthly follow-ups, which included questionnaires, information about contraceptive use, pregnancy testing and HIV testing. Participants received condoms and risk-reduction counseling. Participants also were screened periodically for STDs such as chlamydia, gonorrhea and trichomonas infection.

Almost 57% of participants used depot medroxyprogesterone acetate (DMPA), 34% used norethisterone enanthate (NET-EN), and 8.2% used both types of injectable contraceptives during the study from September 2009 to August 2012.

There were 207 new HIV-1 infections, 152 among DMPA users and 55 among NET-EN users. This resulted in an overall incidence rate of 7.57 per 100 person-years (95% CI, 6.61-8.68), including 8.62 per 100 person-years for DMPA users (95% CI, 7.35-10.11) and 5.67 per 100 person-years for NET-EN users (95% CI, 4.35-7.38).

DMPA users had a greater overall risk for HIV infection vs. NET-EN users (HR: 1.53; 95% CI, 1.12-2.08). No significant difference in results was revealed after further adjustment for number of sexual partners and receptive anal sex.

Baseline seropositivity for herpes simplex virus 2 was associated with an adjusted HR of 2.02 (95% CI, 1.26-3.24) vs. 1.09 (95% CI, 0.78-1.52) for HSV-2 seronegative participants.

According to the researchers, these findings should be tempered by the need for effective birth control to prevent maternal mortality.

“Despite observational findings that seem to implicate DMPA in HIV acquisition, evidence remains mixed, and withdrawal of any common effective contraceptive could increase maternal mortality ratios,” the researchers wrote. “A broad range of stakeholders should continue to assess emerging evidence to establish whether women, in consultation with providers, should consider switching from DMPA to NET-EN in high HIV incidence settings where NET-EN is available.” – by Jen Byrne

Disclosure: Noguchi reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.