Estimation of hazard of death in vertically transmitted HIV-1-infected children for doubly censored failure times and fixed covariates
This work estimates the effect of covariates on survival data when times of both originating and failure events are interval-censored. Proportional hazards model [16] along with log-linear models was applied on a data of 130 vertically infected HIV-1 children visiting the paediatrics
clinic. The covariates considered for the analysis were antiretroviral (ARV) therapy, age at diagnosis, and change in CD4+T cell count. Change in CD4+T cell count was the difference in the last and first count in non-ARV therapy group, while in the ARV therapy group the same was considered
after the start of the treatment. Our findings suggest that children on ARV therapy had significantly lower risk of death (p<0.001). We further investigated the effect of age and change in CD4+T cell count on risk of death. These covariates exhibited a possible association with risk of
death by both the procedures (p<0.0001). The effect of number of years under ARV therapy with diagnosis year as a confounding factor was directly related to longevity. The results obtained by the two procedures gave reasonable estimates. We conclude that when the lengths of intervals are
narrow, we can opt for parametric modeling which is less computationally intensive.
Keywords: HIV/AIDS; antiretroviral therapy; interval censoring; log-linear model; paediatrics; proportional hazard model
Document Type: Research Article
Affiliations: 1: Department of Statistics, University of Delhi, India 2: Department of Paediatrics, Dr Ram Manohar Lohia Hospital, New Delhi, India 3: Department of Neurology, Institute of Human Behaviour and Allied Sciences, Delhi, India
Publication date: 01 February 2011
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