Modeling Survival Time to Death Among TB and HIV Co-infected Adult Patients: an Institution-Based Retrospective Cohort Study

Background Tuberculosis is a serious health threat, particularly for people living with human immunodeficiency virus (HIV), and HIV-positive people are more likely than others to contract the disease. Globally, tuberculosis (TB) is one of the leading causes of death among people living with HIV. The purpose of the current study was to identify factors associated with survival rates of TB/HIV co-infected patients using survival models. Methods A retrospective study was conducted on TB/HIV co-infected adult patients registered and under follow-up at Tepi General Hospital (TGH) and Mizan-Tepi University Teaching Hospital (MTUTH), southwest Ethiopia. All TB/HIV co-infection patients who were registered and under follow-up from 1st January 2015 through 1st January 2020 were considered. The global Schoenfeld test was used to test the proportional hazard (PH) assumption. Various accelerated failure time (AFT) models were compared to determine the best model for the time to death of TB/HIV co-infected patients' data set. Among the most commonly used accelerated failure time models (AFT models), the study used exponential, Weibull, log-logistic, and log-lognormal AFT models. AIC and BIC were used to compare the performance of fitted models. The data were analyzed with the statistical software R. Results Of 363 TB/HIV co-infected patients followed for 60 months, 79 (21.8%) died, while the remaining 284 (78.2%) were censored. The overall median survival time was 15.6 months. The proportional hazard assumption was checked and it was violated. In comparison to other models, the lognormal AFT model performed better. The results of the multivariable lognormal AFT model showed that age, residence, substance use, educational status, clinical stages of the disease, cluster of differentiation 4 (CD4 count/mm(3)), functional status, cotrimoxazole prophylactic therapy use (CPT use), and INH were all found to be significant factors, while gender, illness other than TB, and disclosure of status were insignificant variables at 5% level of significance. Conclusion Current study results revealed that older age, substance use, advanced WHO clinical stages of the disease (stage IV), bedridden functional status, and CD4 less than 200 count/mm(3) were significantly associated with shorter survival time to death of HIV/TB co-infected patients while havingadvanced educational status, being from urban residence, CPT use, and INH significantly increase the survivaltime to death of TB/HIV co-infected patients. Patients with TB/HIV co-infection should be given special attention based on these important factors to improve their health and prolong their lives.