Previous studies have reported improvements in life expectancies of patients on antiretroviral treatment (ART) over time, but it is not clear whether these improvements are explained by changes in baseline clinical characteristics, longer duration on ART or changes in clinical practices.
Two parametric survival models were fitted to mortality data from South African ART cohorts that had linked patient records to the national vital registration system. The first model estimated mortality by age, sex, cohort, baseline CD4 cell count, time since ART initiation and period of ART initiation; the second model included only age, sex, cohort and period of follow-up. Life expectancies were calculated from the estimated mortality rates.
The first model estimated little change in mortality over time: women starting ART at age 35 years, at CD4 cell counts of 200 cells/μl or higher, had life expectancies of 32.7 years [95% confidence interval (CI): 31.6-33.6], 32.4 years (95% CI: 31.3-33.4) and 33.0 years (95% CI: 32.0-34.1) in the 2001-2006, 2007-2009 and 2010-2014 periods, respectively. However, the second model estimated a significant improvement in life expectancy; for all women on ART at age 35 years, corresponding life expectancies were 13.0 years (95% CI: 12.1-14.2), 20.4 years (95% CI: 19.5-21.4) and 26.1 years (95% CI: 25.2-26.9), respectively.
Although life expectancies in South African ART patients have improved over time, these improvements are not observed after controlling for changes in baseline CD4 cell count and ART duration. This suggests that changes in clinical practice and programme scale have had little impact on ART mortality in South Africa.