Increases in adult life expectancy in rural South Africa: valuing the scale-up of HIV treatment

Abstract

The scale-up of antiretroviral therapy (ART) is expected to raise adult life expectancy in populations with high HIV prevalence. Using data from a population cohort of over 101,000 individuals in rural KwaZulu-Natal, South Africa, we measured changes in adult life expectancy for 2000-2011. In 2003, the year before ART became available in the public-sector health system, adult life expectancy was 49.2 years; by 2011, adult life expectancy had increased to 60.5 years--an 11.3-year gain. Based on standard monetary valuation of life, the survival benefits of ART far outweigh the costs of providing treatment in this community. These gains in adult life expectancy signify the social value of ART and have implications for the investment decisions of individuals, governments, and donors.

Fig. 1. Adult life expectancy and the scale-up of ART, 2000–2011

Adult life expectancy is the mean age to which a 15 year old could expect to live if subjected to the full pattern of age-specific mortality rates observed in a population for a given period of time. Annual estimates of adult life expectancy (blue squares) are plotted against year, 2000–2011, with 95% confidence intervals. Public sector provision of ART to adults in this community began in 2004, as indicated by the vertical line.

Fig. 2. Survival curves for 2003 and 2011

Kaplan-Meier survival curves for 2003 (solid red line) and 2011 (broken blue line) were estimated for the population under surveillance. Each curve displays the probability that someone would be alive at a given age if subjected to the full pattern of age-specific mortality rates observed in that year. Conditional on survival to fifteen years, the median age at death was 42.6 years (95% CI 41.2, 44.3) in 2003 and 60.7 years (95% CI 58.8, 62.7) in 2011, a difference of 18.1 years.

Fig. 3. Probability distributions of length of life in 2003 and 2011

Distributions of lengths of life are presented for 2003 (solid red line) and 2011 (broken blue line). The thin green line displays the distribution of HIV- cause–deleted lengths of life for 2001–2010, which are based on mortality rates that exclude HIV- related deaths. The proportion of deaths occurring in young adult- hood declined between 2003 and 2011, but there was still evidence of excess HIV-related mortality among young adults in 2011 (by comparison to the HIV-cause– deleted distribution of lengths of life).

Fig. 4. HIV-cause-deleted adult life expectancy

Trends in adult life expectancy (red line) and HIV-cause-deleted adult life expectancy (blue line) for 2001–2010. HIV-cause-deleted life expectancy was estimated excluding deaths due to HIV, as identified by verbal autopsy in the Africa Centre surveillance. Whereas adult life expectancy increased after 2003, there was no systematic trend in HIV-cause-deleted adult life expectancy.