Objectives: To compare rates of mother to child transmission of HIV and infant survival in women-infant dyads receiving different interventions in a prevention of Mother to Child Transmission (pMTCT) program in western Kenya.
Design: Retrospective cohort study using prospectively collected data stored in an electronic medical record system.
Setting: Eighteen HIV clinics in western Kenya.
Population: HIV-exposed infants enrolled between February 2002 and July 2007, at any of the United States Agency for International Development-Academic Model Providing Access To Healthcare partnership clinics.
Main outcome measures: Combined endpoint (CE) of infant HIV status and mortality at 3 and 18 months.
Analysis: Descriptive statistics, chi Fisher exact test, and multivariable modeling.
Results: Between February 2002 and July 2007, 2477 HIV-exposed children were registered for care by the United States Agency for International Development-Academic Model Providing Access To Healthcare partnership pMTCT program before 3 months of age. Median age at enrollment was 6.1 weeks; 50.4% infants were male. By 3 months, 31 of 2477 infants (1.3%) were dead and 183 (7.4%) were lost to follow-up. One thousand (40%) underwent HIV DNA Polymerase Chain Reaction virologic test at a median age of 8.3 weeks: 5% were HIV infected, 89% uninfected, and 6% were indeterminate. Of the 968 infants with specific test results or mortality data at 3 months, the CE of HIV infection or death was reached in 84 of 968 (8.7%) infants. The 3-month CE was significantly impacted (A) by maternal prophylaxis [51 of 752 (6.8%) combination antiretroviral therapy (cART); 8 of 69 (11.6%) single-dose nevirapine (sdNVP); and 25 of 147 (17%) no prophylaxis (P < 0.001)] and (B) by feeding method for the 889 of 968 (91.8%) mother-infant pairs for which feeding choice was documented [5 of 29 (17.2%) exclusive breastfeeding; 13 of 110 (11.8%) mixed feeding; and 54 of 750 (7.2%) formula feeding (P = 0.041)]. Of the 1201 infants > or = 18 months of age: 41 (3.4%) were deceased and 329 (27.4%) were lost to follow-up. Of 621 of 831 (74.7%) infants tested, 65 (10.5%) were infected resulting in a CE of 103 of 659 (15.6%). CE differed significantly by maternal prophylaxis [52 of 441 (11.8%) for cART; 13 of 96 (13.5%) for sdNVP; and 38 of 122 (31.2%) no therapy group (P < 0.001)] but not by feeding method for the 638 of 659 (96.8%) children with documented feeding choice [7 of 35 (20%) exclusive breastfeeding, 14 of 63 (22.2%) mixed, and 74 of 540 (13.7%) formula (P = 0.131)]. On multivariate analysis, sdNVP (odds ratio: 0.4; 95% confidence interval: 0.2 to 0.8) and cART (odds ratio: 0.3; 95% confidence interval: 0.2 to 0.6) were associated with fewer CE. At 18 months, feeding method was not significantly associated with the CE.
Conclusions: Though ascertainment bias is likely, results strongly suggest a benefit of antiretroviral prophylaxis in reducing infant death and HIV infection, but do not show a benefit at 18-months from the use of formula. There was a high rate of loss to follow up, and adherence to the HIV infant testing protocol was less than 50% indicating the need to address barriers related to infant HIV testing, and to improve outreach and follow-up services.