Differences in healthy longevity by HIV status and viral load among older South African adults: an observational cohort modelling study

Abstract

BackgroundThe population of people living with HIV in South Africa is rapidly ageing. The co-incidence of demographic ageing and a high HIV burden means that understanding the combined impacts of HIV and antiretroviral therapy (ART) on healthy longevity is of key importance in South Africa. MethodsWe use longitudinal data from the 2015 and 2018 waves of the population-based study, Health and aging in Africa: a longitudinal study of an INDEPTH community in South Africa, to explore life expectancy and disability-free life expectancy of adults aged 45 years and older in rural South Africa. Individuals were classified into one of three health states: disability-free (defined as no reported activities of daily living [ADL] limitations), ADL disabled individuals (defined as difficulty with ≥1 ADL activities), and dead. Annual transition probabilities were modelled using multinomial logistic regression, stratified by initial disability state. We used these estimated transition probabilities as the input for a microsimulation model generating 100 000 simulated life courses, which were used to estimate life expectancy and disability-free life expectancy. CIs, which reflect both the uncertainty of the estimated parameters and the uncertainty from the microsimulation, were created by re-estimating the above analysis sequence using 499 bootstrap re-samples for each age group under study. We took the central 95% of the distribution of these bootstrapped parameters as the 95% CI. FindingsWe found a gradient in remaining life expectancy based on HIV serostatus and viral suppression. At age 45 years, an HIV-negative man could expect to live an additional 27·2 years (95% CI 25·8–29·1), compared with 24·1 years (20·9–27·2) for an HIV-positive, virally suppressed man (defined as <200 copies/mL) and 17·4 years (15·0–20·3) for an HIV-positive, unsuppressed man. Patterns were similar among women. Individuals achieving viral control could expect to live nearly as many disability-free years as HIV-negative individuals at age 45 years. By age 65 years, the healthy longevity of these two groups was indistinguishable. InterpretationThese findings highlight the major population health and longevity gains that are possible when the 90–90–90 goals are realised. We found that viral suppression of HIV-positive individuals through ART has increased lifespan and healthspan to similar levels as observed among HIV-negative individuals. Achievement of viral suppression for millions of people with HIV, especially in high prevalence contexts such as South Africa, is critical for ensuring healthy population ageing. FundingNational Institutes of Health.