A THESIS SUBMITTED TO THE DEPARTMENT OF STATISTICS, COLLEGE OF NATURAL SCIENCE, ARBA MINCH UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE IN APPLIED STATISTICS JUNE, 2019

Abstract

The Human Immune deficiency Virus is a major health problem in the world and failure to implement prevention programs was result in an increased number of infections among newborns. HIV infected children should start ART in order to reduce AIDs related morbidity and mortality, or to improve their survival time. The main purpose of this study was to assess the predictors of longitudinal CD4 cell count and survival time of HIV-infected children who were under ART. The study considered a cohort of 201 HIV infected children who were aged 15 years or younger and they were on ART from March 1, 2006 to January 30, 2010 EC at Adama Hospital. To analyze our data we employed descriptive method, linear mixed effect model, cox-PH model and joint models for longitudinal, survival and both outcomes respectively. The results of both separate and joint models were consistent. The result from the joint model showed longitudinal CD4 cell count is significantly associated with survival time. The estimated association parameter  is -0.10, this indicate both outcome is negatively associated and higher values of the CD4 cell count associated with better survival. The two outcomes were associated, the joint model were used to handle the associations between them to obtain valid and efficient estimate. The result from longitudinal sub-model reviled that observation time, age, WHO clinical stage, history of TB, and functional status had significantly associated with mean change in the square root of CD4 cell count. Furthermore, from the survival sub-model we found the survival probability of HIV infected children were determined by WHO clinical stage, functional status, history of TB, and BMI. Future extension of this research could be possible to account for CD4 cell percentage.