Long-Term Survival in HIV Positive Patients with up to 15 Years of Antiretroviral Therapy

Background: Life expectancy has increased for newly diagnosed HIV patients since the inception of combination antiretroviral treatment (cART), but there remains a need to better understand the characteristics of long-term survival in HIV-positive patients. We examined long-term survival in HIV-positive patients receiving cART in the Australian HIV Observational Database (AHOD), to describe changes in mortality compared to the general population and to develop longer-term survival models. Methods: Data were examined from 2,675 HIV-positive participants in AHOD who started cART. Standardised mortality ratios (SMR) were calculated by age, sex and calendar year across prognostic characteristics using Australian Bureau of Statistics national data as reference. SMRs were examined by years of duration of cART by CD4 and similarly by viral load. Survival was analysed using Cox-proportional hazards and parametric survival models. Results: The overall SMR for all-cause mortality was 3.5 (95% CI: 3.0-4.0). SMRs by CD4 count were 8.6 (95% CI: 7.2-10.2) for CD4<350 cells/mu l; 2.1 (95% CI: 1.5-2.9) for CD4 = 350-499 cells/mu l; and 1.5 (95% CI: 1.1-2.0) for CD4 >= 500 cells/mu l. SMRs for patients with CD4 counts<350 cells/mu l were much higher than for patients with higher CD4 counts across all durations of cART. SMRs for patients with viral loads greater than 400 copies/ml were much higher across all durations of cART. Multivariate models demonstrated improved survival associated with increased recent CD4, reduced recent viral load, younger patients, absence of HBVsAg-positive ever, year of HIV diagnosis and incidence of ADI. Parametric models showed a fairly constant mortality risk by year of cART up to 15 years of treatment. Conclusion: Observed mortality remained fairly constant by duration of cART and was modelled accurately by accepted prognostic factors. These rates did not vary much by duration of treatment. Changes in mortality with age were similar to those in the Australian general population.