Contraception for women on ART – a balancing act

Pregnancy rates in HIV-positive women using contraceptives and efavirenz-based or nevirapine-based antiretroviral therapy in Kenya: a retrospective cohort study.

Patel RC, Onono M, Gandhi M, Blat C, Hagey J, Shade SB, Vittinghoff E, Bukusi EA, Newmann SJ, Cohen CR. Lancet HIV. 2015 Nov;2(11):e474-82. doi: 10.1016/S2352-3018(15)00184-8. Epub 2015 Oct 22.

Background: Concerns have been raised about efavirenz reducing the effectiveness of contraceptive implants. We aimed to establish whether pregnancy rates differ between HIV-positive women who use various contraceptive methods and either efavirenz-based or nevirapine-based antiretroviral therapy (ART) regimens.

Methods: We did this retrospective cohort study of HIV-positive women aged 15-45 years enrolled in 19 HIV care facilities supported by Family AIDS Care and Education Services in western Kenya between Jan 1, 2011, and Dec 31, 2013. Our primary outcome was incident pregnancy diagnosed clinically. The primary exposure was a combination of contraceptive method and efavirenz-based or nevirapine-based ART regimen. We used Poisson models, adjusting for repeated measures, and demographic, behavioural, and clinical factors, to compare pregnancy rates among women receiving different contraceptive and ART combinations.

Findings: 24 560 women contributed 37 635 years of follow-up with 3337 incident pregnancies. In women using implants, adjusted pregnancy incidence was 1.1 per 100 person-years (95% CI 0.72-1.5) for nevirapine-based ART users and 3.3 per 100 person-years (1.8-4.8) for efavirenz-based ART users (adjusted incidence rate ratio [IRR] 3.0, 95% CI 1.3-4.6). In women using depot medroxyprogesterone acetate, adjusted pregnancy incidence was 4.5 per 100 person-years (95% CI 3.7-5.2) for nevirapine-based ART users and 5.4 per 100 person-years (4.0-6.8) for efavirenz-based ART users (adjusted IRR 1.2, 95% CI 0.91-1.5). Women using other contraceptive methods, except for intrauterine devices and permanent methods, had 3.1-4.1 higher rates of pregnancy than did those using implants, with 1.6-2.8 higher rates in women using efavirenz-based ART.

Interpretation: Although HIV-positive women using implants and efavirenz-based ART had a three-times higher risk of contraceptive failure than did those using nevirapine-based ART, these women still had lower contraceptive failure rates than did those receiving all other contraceptive methods except for intrauterine devices and permanent methods. Guidelines for contraceptive and ART combinations should balance the failure rates for each contraceptive method and ART regimen combination against the high effectiveness of implants.

Abstract access  [1]

Editor’s notes: Contraceptive use by women living with HIV who wish to prevent pregnancy remains a key component of the strategy to eliminate new HIV infections among children. Progesterone-based implants are the most effective reversible contraceptive method, but there is some evidence to suggest that their efficacy may be reduced in women receiving efavirenz (EFV)-based antiretroviral therapy (ART).

Overall contraceptive use in these women of childbearing age was low – 70% of the time women were using no contraception or less effective methods only (condoms or natural methods). Overall pregnancy rates were low with the hormonal implant, broadly equivalent to women with intrauterine devices and much lower than with depot injectable and oral contraceptive methods. There was some evidence that the rate of pregnancy in women using the implant was higher for women on EFV-based ART compared to women on nevirapine-based ART. However, the rate of pregnancy remained lower than with injectable or oral contraceptives.

Although this may provide some support to the evidence of reduced implant efficacy with EFV-based ART, it is clear that this can still be an effective contraceptive method. This evidence seems unlikely to change existing WHO recommendations that all forms of contraception should be available to women living with HIV. The low rate of contraceptive use highlights the need to improve access for women living with HIV to quality integrated sexual and reproductive health services. The data from this study suggest that for women wishing to avoid pregnancy, the choice of contraceptive method may be more important than the choice of ART regimen.  

Africa [8]
Kenya [9]
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