Effect of age at initiation of antiretroviral therapy on treatment outcomes; A retrospective cohort study at a large HIV clinic in southwestern Uganda

Background The prevalence of HIV infection among older persons is increasing yet older age at initiation of antiretroviral therapy (ART) may be associated with poorer treatment outcomes including mortality. However, majority of these studies have been done in the western world and there is limited data in resource limited settings. Our study used routinely collected health facility data to assess trends in age at initiation of ART, the effect of age at ART initiation on mortality and immunological response at a large urban hospital in south western Uganda. Methods We conducted a retrospective records review of patients attending the HIV clinic at Mbarara Regional Referral Hospital in western Uganda. We retrieved records for 8,533 patients who started ART between January 2006 and December 2012. Their data had been collected and stored as part of the larger International Epidemiological Database for the Evaluation of AIDS (IeDEA). Age was stratified into three categories namely; 18-34 (young adults), 35-49 (mid-age) and 50 years or older (older adults). Survival analysis procedures with Kaplan-Meier's plots were used to calculate the survival probability with mortality as the endpoint and Poisson regression analysis used to determine the adjusted relative risks (RR) of mortality. Results The proportion of young adults and patients at WHO stage I initiating ART increased steadily over the 7-year period. Older age at ART initiation (> = 50 years) was associated with a higher risk of mortality with adjusted relative risk (RR) at 1.63, (95% CI 1.26-2.11) compared to younger age. Male gender, WHO stages III and IV, lower CD4 count and lower body mass index were also all independently and significantly associated with higher risk for mortality. Older adults also had a poorer immunological response RR = 1.79 (95% CI 0.893.58) but was not statistically significant. Conclusions Following ART initiation, older adults compared to the young, have a higher risk of mortality. This age group should be targeted first for 'screen and treat' approach. Optimization of ART treatment regimens for this age group is also required to reduce mortality and improve immunological response.