Survival and risk factors for mortality among HIV/Tuberculosis co-infected patients on antiretroviral therapy in a resource limited setting

Abstract

Background: Tuberculosis is the most common opportunistic infection and most frequent cause of mortality among HIV-infected persons in resource constrained settings and the number of patients with co-infection continues to grow rapidly. Objective: To determine the survival and predictors of mortality among HIV/Tuberculosis co-infected patients on antiretroviral therapy at Wilkins Infectious Disease Hospital (WIDH), Harare. Methods: A retrospective study in a cohort of 207 HIV/TB co-infected patients who presented to WIDH and started ART between 1 December 2004 and 1 March 2010 was carried out. A retrospective review of patient medical records was done. Kaplan-Meier method was used to construct survival functions, the log rank test was used to test equality of survivor functions across strata; we performed univariate and multivariate analysis and constructed a Cox-proportional hazards model to determine factors that determine survival in HIV/TB co-infected patients on ART. Results: There were 45 (21.7%) deaths at the end of the study among whom 18 (40%) died in those who had extra-pulmonary tuberculosis and 27 (60%) in patients with pulmonary tuberculosis. The mortality rate was 9.8 deaths/100person years of follow-up. The cumulative mortality at 3, 6 and 12 months was 1%, 5% and15% respectively. Independent predictors of mortality were CD4 count<50cells/ul adjusted Hazard ratio [AHR] 2.37, 95% CI (1.158-4.856)], WHO stage four at baseline [AHR=2.69 95%CI (1.35-5.34)], cotrimoxazole use [AHR=0.29 95%CI (0.86-0.89)]. Haemoglobin was not found to be a risk factor. Conclusion: Mortality was high in the first year relative to subsequent years. There was increased risk of death in patients co infected with HIV and TB who presented to the clinic with late stage disease as indicated by the WHO clinical stage criterion and low CD4 count at baseline and these were strong predictors of mortality. Collaboration of HIV/TB activities should be reemphasized and scale up of patients to access ART or effective treatment and control of TB among co infected patients. Increasing access of cotrimoxazole by patients on ART and interventions to identify patients before they develop these clinical markers will improve survival and increase benefits of therapy.