Late postnatal transmission of HIV-1 and associated factors
ABSTRACT The present study was undertaken to determine the risk and timing of late postnatal transmission (LPT) of human immunodeficiency virus type 1 (HIV-1).
Breast-fed infants previously enrolled in 2 trials of antiretroviral prophylaxis were monitored in Malawi. Kaplan-Meier and proportional hazard models assessed cumulative incidence and association of factors with LPT.
Overall, 98 infants were HIV infected, and 1158 were uninfected. The cumulative risk of LPT at age 24 months was 9.68% (95% confidence interval, 7.80%-11.56%). The interval hazards at 1.5-6, 6-12, 12-18, and 18-24 months were 1.22%, 4.05%, 3.48%, and 1.27%, respectively.
The risk of LPT beyond 6 months is substantial. Weaning at 6 months could prevent >85% of LPT.
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- "This has also been observed in clinical trials (Taha et al., 2007). Table 1 shows results from the Kaplan-Meier (KM) and proportional hazards (PH) analyses on both the observed and imputed data. "
ABSTRACT: The timing of mother-to-child transmission (MTCT) of HIV is critical in understanding the dynamics of MTCT. It has a great implication to developing any effective treatment or prevention strategies for such transmissions. In this paper, we develop an imputation method to analyze the censored MTCT timing in presence of auxiliary information. Specifically, we first propose a statistical model based on the hazard functions of the MTCT timing to reflect three MTCT modes: in utero, during delivery and via breastfeeding, with different shapes of the baseline hazard that vary between infants. This model also allows that the majority of infants may be immuned from the MTCT of HIV. Then, the model is fitted by MCMC to explore marginal inferences via multiple imputation. Moreover, we propose a simple and straightforward approach to take into account the imperfect sensitivity in imputation step, and study appropriate censoring techniques to account for weaning. Our method is assessed by simulations, and applied to a large trial designed to assess the use of antibiotics in preventing MTCT of HIV.12/2010; 2(1). DOI:10.2202/1948-4690.1018
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Conference Paper: Simulation design for radial Bragg fiber[Show abstract] [Hide abstract]
ABSTRACT: By simplifying the structure of the cladding layers, an unequal-period radial Bragg fiber has been proposed. Furthermore, in this Bragg fiber, the number of cladding medium layers can be reduced. Some computer simulation results have been obtained. The simplification of the cladding layers is very useful for the fabrication of Bragg fiber.Communications, Circuits and Systems, 2004. ICCCAS 2004. 2004 International Conference on; 07/2004