18-month effectiveness of short-course antiretroviral regimens combined with alternatives to breastfeeding to prevent HIV mother-to-child transmission.

OBJECTIVE: We assessed the 18-month effectiveness of short-course (sc) antiretroviral peripartum regimens combined with alternatives to prolonged breastfeeding to prevent mother-to-child transmission (MTCT) of HIV-1 in Abidjan, Côte d'Ivoire. METHODOLOGY: HIV-1 infected pregnant women received from >/=32-36 weeks of gestation scZidovudine (ZDV)+/-Lamivudine (3TC)+single-dose Nevirapine (sdNVP) at delivery within the ANRS 1201/1202 DITRAME-Plus cohort (2001-2003). Neonates received a sdNVP+7-day ZDV prophylaxis. Two infant-feeding interventions were systematically offered free of charge: formula-feeding or exclusive shortened breastfeeding with early cessation from four months. The reference group was the ANRS 049a DITRAME cohort (1994-2000) exposed to scZDV from 36 weeks, then to prolonged breastfeeding. Pediatric HIV infection was defined by a positive plasma HIV-1 RNA at any age, or if aged >/=18 months, a positive HIV-1 serology. Turnbull estimates of cumulative transmission risks (CTR) and effectiveness (HIV-free survival) were compared by exposure group using a Cox model. FINDINGS: Among 926 live-born children enrolled, 107 (11.6%) were HIV-infected at 18 months. CTRs were 22.3% (95% confidence interval[CI]:16-30%) in the 238 ZDV long-term breastfed reference group, 15.9% (CI:10-27%) in the 169 ZDV+sdNVP shortened breastfed group; 9.4% (CI:6-14%) in the 195 ZDV+sdNVP formula-fed group; 6.8% (CI:4-11%) in the 198 ZDV+3TC+sdNVP shortened breastfed group, and 5.6% (CI:2-10%) in the 126 ZDV+3TC+sdNVP formula-fed group. Each combination had a significantly higher effectiveness than the ZDV long-term breastfed group except for ZDV+sdNVP shortened breastfed children, ranging from 51% (CI:20-70%) for ZDV+sdNVP formula fed children to 63% (CI:40-80%) for ZDV+3TC+NVPsd shortened breastfed children, after adjustment for maternal eligibility for antiretroviral therapy (ART), home delivery and low birth-weight. Substantial MTCT risk reductions are reachable in Africa, even in short-term breastfed children. The two sc antiretroviral combinations associated to any of the two infant feeding interventions, formula-feeding and shortened breastfeeding, reduce significantly MTCT with long-term benefit until age 18 months and without increasing mortality.

Field efficacy of zidovudine, lamivudine and single-dose nevirapine to prevent peripartum HIV transmission.

OBJECTIVES: In Africa, single-dose nevirapine (NVPsd), short regimens of zidovudine (ZDV) or ZDV + lamivudine (3TC) are recommended to prevent peripartum mother-to-child HIV transmission (PMTCT). We evaluated the 6-week field efficacy of two more PMTCT drug combinations. DESIGN: An open-label intervention cohort in Abidjan. METHODS: In 2001-2002, consenting women started oral ZDV 300 mg twice daily (bid) at > or =36 weeks of gestation, with 600 mg of ZDV + 200 mg NVPsd orally at beginning of labour. In 2002-2003, the antepartum regimen at > or =32 weeks comprised ZDV as previously + 3TC 150 mg bid; the labour dose comprised ZDV + NVPsd as previously + 300 mg 3TC orally. Neonates received ZDV syrup (2 mg/kg per 6 h) for 7 days + NVPsd syrup (2 mg/kg) on day 2 in both periods. Each woman was assisted to either use breast milk substitutes or breastfeed exclusively. Paediatric HIV infection was diagnosed by plasma HIV RNA viral load at 4 weeks, confirmed at 6 weeks. The reference group was a cohort receiving a short regimen of ZDV > or = 36-38 weeks in 1995-2000 in the same population. RESULTS: A total of 1144 HIV-infected pregnant women were included: 351 with ZDV, 420 with ZDV + NVPsd and 373 with ZDV + 3TC + NVPsd; 1010 livebirths were eligible for analysis; 79 children were HIV-infected peripartum. Six-week transmission probability was 6.5% [95% confidence interval (CI), 3.9-9.1%) with ZDV + NVPsd, a 72% reduction compared with ZDV alone (95% CI, 52-88%; P = 0.0002 adjusted on maternal CD4, clinical stage and breastfeeding). It was 4.7% (95% CI, 2.4-7.0%) with ZDV + 3TC + NVPsd (P = 0.34 compared with ZDV + NVPsd). CONCLUSIONS: A short-course of ZDV + NVPsd prevents most peripartum HIV transmission in Africa. This regimen could be added to international guidelines.

Estimating the efficacy of interventions to prevent mother-to-child transmission of human immunodeficiency virus in breastfeeding populations: comparing statistical methods.

Postnatal transmission of human immunodeficiency virus infection through breastfeeding complicates evaluating the efficacy of interventions aimed to reduce mother-to-child transmission risk. Results from trials in Africa evaluating either peripartum antiretroviral therapy or refraining from breastfeeding show an estimated long-term efficacy at 15-24 months of age between 25 and 50 percent. Differences in statistical methods, duration of follow-up, and age at weaning hinder direct comparison between trials. The authors recently outlined theoretically preferred statistical methods for evaluating interventions aimed to reduce risk of mother-to-child transmission of human immunodeficiency virus. When multiple test results and/or supplementary information is available, the more sophisticated methods account for the fact that exact age at infection is unknown, that risk for infection ends at weaning, or that censoring due to death may be informative. The authors apply these methods to four scenarios, using data from four randomized trials carried out in Africa between 1995 and 2000. The authors' findings suggest that, to estimate the cumulative proportion infected at age 6 weeks, a standard Kaplan-Meier approach is likely to give valid results. For estimation of this proportion at age 18 months, more sophisticated methods, such as the extension of the Kaplan-Meier procedure to interval-censored data and competing risks, would be preferred.