Among the 1785 HIV-1-uninfected women enrolled in the Partners PrEP study, the median age was 33 years [interquartile range (IQR) 28–38] and median partnership duration with their HIV-1-infected partner was 12 years (IQR 6–18) (Table 1). Women reported an average of 3 (IQR 1–5) children with their study partner, with 15% having no children. Curable sexually transmitted infections were identified in 10%, and unprotected sex in the past month was reported by 23%.
Approximately half of the study population reported contraceptive use at enrollment, with injectable hormones the most common method reported (27% of all women). During follow-up, 14% of women initiated oral pills, 20% initiated injectable hormones, and 6% received implants. In total, hormonal contraceptives were used during 51% of all nonpregnant follow-up time: oral contraceptives 11%, injectables 31%, and implants 8%. No contraception was reported during 35% of nonpregnant follow-up time and other forms of contraception were reported for the remaining 14%.
A total of 288 pregnancies were observed in 267 women (179 assigned PrEP and 88 assigned placebo). Pregnancy incidence and outcomes did not differ across study arms. Among women reporting no contraceptive use, pregnancy incidence was 15.4% per year: 14.6 and 17.4% for women assigned PrEP and placebo, respectively (Table 2). Women reporting oral contraceptive use had similar pregnancy incidence compared to women reporting no contraception; oral contraceptive effectiveness did not differ significantly for women assigned PrEP [adjusted hazard ratio (aHR) 0.96] compared to placebo (aHR 0.55, P-value for difference in aHRs = 0.24). Women reporting injectable contraception had 75–80% reduction in pregnancy incidence compared to women not using contraception, and this did not differ by randomization arm (PrEP: aHR 0.26, P < 0.001; placebo: aHR 0.19, P < 0.001; P-value for difference = 0.47). Further, effectiveness during the first 3 months after injectable contraception initiation and after longer duration use did not differ by randomization arm (data not shown). Implantable contraception was highly effective for pregnancy prevention (incidence <1% per year) in both PrEP and placebo arms. In sensitivity analyses, excluding follow-up time when the PrEP study drug was withheld and when adherence to PrEP/placebo was estimated to be poor (16% of nonpregnant follow-up time), the results for all contraceptive methods were essentially the same (data not shown).
AIDS. 2014;28(12):1825-1830. © 2014 Lippincott Williams & Wilkins
Lippincott Williams & Wilkins