Linear Mixed Modeling of CD4 Cell Counts of HIV-Infected Children Treated with Antiretroviral Therapy

Background. Human immunodeficiency virus (HIV) is a major health problem in the world, and failure to implement prevention programs results in an increased number of infections among newborns. The goal of this study was to investigate the evolution and determinants of cluster of differentiation four (CD4) cell count among HIV-infected children who were under antiretroviral therapy (ART). Methods. We follow up a cohort of 201 children aged under fifteen years from October 2013 to March 2017 at Adama Hospital in Ethiopia. To get insight into the data, exploratory data analysis was performed on the change in the longitudinal CD4 cell count. Results. At the baseline, the average number of CD4 cell counts was 468.5 cells/mm3 of blood with a standard deviation of 319.11 cells/mm3. Here, we employed the random intercept and the random slope linear mixed-effects model to analyze the data. Among predictor variables, observation time, baseline age, WHO clinical stage, the history of tuberculosis (TB), and functional status were determinant factors for the mean change in the square root of the CD4 cell count. Conclusions. The finding revealed that the change in the square root of the CD4 cell count increases with an increment of age at diagnosis. Regarding WHO clinical stages of patients, those who were in stage III and stage IV of the HIV/AIDs disease stages relatively had lower CD4 cell counts than stage I patients. This shows the change in the square root of CD4 cell counts of stage III and stage IV patients was 6.43 and 9.28 times lower than stage I patients, respectively. Similarly, we noticed that observation time, the history of TB, and functional status were significantly associated with the mean change in the square root of the CD4 cell count.