Background: The co-infection of TB/HIV poses a significant burden in the health care system of developing countries like Ethiopia. There are conflicting results on preference of the time to initiate anti-retroviral therapy (ART) and hence assessing the survival experience and treatment outcomes associated with ART initiation is crucial to settle the controversies. The study compared the treatment outcomes in early versus later ART initiation in TB/HIV co-infected patients. Methods: A retrospective cohort study was conducted in Ayder Comprehensive Specialized Hospital and Mekelle Referral Hospital on 77 and 105 patients that started ART early and lately, respectively. An assumption for proportional hazard was met. Kaplan-Meier and life-table analyses were used to compare survival curves; and an independent samples t -test was used to compare means of the continuous variables between the two cohorts. Moreover, incidence per 100 persons-years were employed to crudely determine new morality rates and Cox regression analysis was done to find out the effects of independent variables on the outcome variables. Results: The mean survival time was 5.8 months after ART initiation. A 9.9 and 5.5 new incident mortality rates per 10,000 persons–years for the early and late ART initiation were observed, respectively. There was a statistically significant difference in mean CD4 + T cells between early (208.20 ± 11.94 cells/mm 3 ) and late (245.94 ± 11.69 cells/mm 3 ) ART initiators (t 180 = -2.213, p < 0.028). Additionally, late initiators had a better survival chance at all levels of time (Log Rank c 2 =5.56, p <0.018) than early initiators. Having normal body mass index [adjusted hazard ratio [AHR=0.263; 95% confidence interval [CI]: 0.089–0.778] and having a ‘working’ baseline functional status [AHR=0.151; 95% CI: 0.054–0.427] were found to be preventive factors from death. However, patients with < 250 CD4 + T cells/mm 3 were more likely to die earlier [AHR=12.023; 95%: 1.588–91.005] than their counterpart groups. Conclusion: This study highlights that TB/HIV co-infected patients with moderate immunosuppression who started their ART early had worse outcome than those who started their ART lately. Moreover, body mass index, baseline functional status, and CD4 count were found to be independent predictors of mortality. Keywords: Treatment outcome, early ART initiation, late ART initiation, TB/HIV co-infection

Background: The co-infection of TB/HIV poses a significant burden in the health care system of developing countries like Ethiopia. There are conflicting results on the preference of the time to initiate antiretroviral therapy (ART) and hence assessing the survival experience and treatment outcomes associated with ART initiation is crucial to settle the controversies. The study compared the treatment outcomes in early versus later ART initiation in TB/HIV co-infected patients. Methods: A retrospective cohort study was conducted in Ayder Comprehensive Specialized Hospital and Mekelle Referral Hospital on 77 and 105 patients that started ART early and lately, respectively. An assumption for proportional hazard was met. Kaplan-Meier and life-table analyses were used to compare survival curves; and an independent samples t-test was used to compare means of the continuous variables between the two cohorts. Moreover, incidence per 100 persons-years was employed to crudely determine new morality rates, and Cox regression analysis was done to find out the effects of independent variables on the outcome variables. Results: The mean survival time was 5.8 months after ART initiation. A 9.9 and 5.5 new incident mortality rates per 10,000 persons–years for the early and late ART initiation were observed, respectively. There was a statistically significant difference in mean CD4+ T cells between early (208.20 ± 11.94 cells/mm3) and late (245.94 ± 11.69 cells/mm3) ART initiators (t180 = -2.213, p < 0.028). Additionally, late initiators had a better survival chance at all levels of time (Log Rank c2=5.56, p<0.018) than early initiators. Having normal body mass index [adjusted hazard ratio [AHR=0.263; 95% confidence interval [CI]: 0.089–0.778] and having a ‘working’ baseline functional status [AHR=0.151; 95% CI: 0.054–0.427] were found to be preventive factors from death. However, patients with < 250 CD4+ T cells/mm3 were more likely to die earlier [AHR=12.023; 95%: 1.588–91.005] than their counterpart groups.Conclusion: TB/HIV co-infected patients who had a CD4 count of below 250 cells/ul started ART regimen within two weeks of TB treatment initiation were found to have better survival outcomes than those who start ART beyond two weeks in the study settings. Moreover, female patients were more likely to die than males and, patients with the functional status of bedridden were more likely to die in contrast to working and ambulatory functional status. Moreover, body mass index, baseline functional status, and CD4 count were found to be independent predictors of mortality.