Joint Modeling in Detecting Predictors of Cd4 Cell Count and Status of Tuberculosis Among HIV Infected Patients Under HAART at Felege Hiwot Teaching and Specialized Hospital, North-west Ethiopia

Abstract Background: Globally, the number of TB patients who had been diagnosed with HIV status reached 2.1 million, which is equivalent to 34 % of notified cases of TB. This research was conducted with the objective to identify potential predictors for the status of TB and CD4 cell count for adult HIV patients at Felege Hiwot Teaching and Specialized Hospital North-west Ethiopia.Methods: A retrospective repeated measures were taken from a sample of 226 HIV patients. Separate and joint models were conducted for data analysis of CD4 cell count and TB status of HIV infected patients. Results: The descriptive statistics indicates that among the HIV patients under HAART, 26.6% had additional TB cases. Hence, the expected number of CD4 cell count of HIV patients who were co-infected with TB was decreased by 2.34 as compared to HIV patients who were free from TB. In joint analysis, age, opportunistic infectious disease, adherence to medication, body mass index and social supports were significantly associated with CD4 cell count and TB status. In addition, one-way interaction terms (time * educational level) was also associated with both outcomes. As patients’ age increased by one year, the expected number of CD4 cell count was decreased by 0.025 cells per/mm3 keeping the other variables constant. The expected number of CD4 cell count for patients whose status were ambulatory was decreased by 3.95 as compared to working status. Both separate and joint modeling approach revealed consistent results for significant predictors. However, joint models were more adequate and efficient. Conclusions: Among the predictors of CD4 cell count and TB status, WHO stages, age of patients, functional status of patients, hemoglobin level and residence area were significant predictors for the variable of interests. More attention should be given for HIV/TB co- infected ambulatory and bedridden patients.