Statistical analysis of zidovudine (AZT) effect on CD4 cell counts in HIV disease

Statistics in Medicine
A J McNeil, S M Gore

Abstract

We fit a class of random effects linear growth curve models for the square root of CD4 count to serial marker data from 164 HIV-positive individuals with known (or accurately estimated) dates of seroconversion and at least 10 CD4 measurements each (median 16). We do so by adopting a Bayesian viewpoint and using the Markov chain Monte Carlo technique Gibbs sampling. In particular, we examine the effect of the antiretroviral treatment zidovudine on the square root of CD4 series for the 136 patients who took the drug. Treatment effects are modelled by positing recoveries in square root of CD4 level proportional to current immuno-competence and changes in slope proportional to current rate of square root of CD4 loss. Both fixed and random treatment effects are considered and models are criticized and compared using Bayesian predictive methodology and checking data which comprise 424 new observations. Results indicate re-elevation of square root of CD4 level is associated with treatment but the effect, though significant, is mostly of small magnitude and is possibly transient; models neglecting consideration of treatment fit the checking data almost as well. Best overall model estimates mean rate of square root of CD4 loss per annum...Continue Reading

Citations

Sep 2, 2006·Statistics in Medicine·Deborah Ashby
Apr 20, 2004·Mathematical Biosciences·Yoann Madec, Caroline Japhet
Aug 21, 2001·International Journal of Epidemiology·Y YazdanpanahK A Freedberg
Mar 29, 2000·Journal of Acquired Immune Deficiency Syndromes : JAIDS·C A SabinC Loveday
May 8, 2001·Statistical Methods in Medical Research·G M Raab, T Parpia
Aug 16, 2003·Science·Brian G Williams, Christopher Dye

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