Ageing and long-term CD4 cell count trends in HIV-positive patients with 5 years or more combination antiretroviral therapy experience

Objectives The aim of this study was to describe the long-term changes in CD4 cell counts beyond 5 years of combination antiretroviral therapy (cART). If natural ageing leads to a long-term decline in the immune system via low-grade chronic immune activation/inflammation, then one might expect to see a greater or earlier decline in CD4 counts in older HIV-positive patients with increasing duration of cART. Methods Retrospective and prospective data were examined from long-term virologically stable HIV-positive adults from the Australian HIV Observational Database. We estimated mean CD4 cell count changes following the completion of 5 years of cART using linear mixed models. Results A total of 37916 CD4 measurements were observed for 892 patients over a combined total of 9753 patient-years. Older patients (>50 years old) at cART initiation had estimated mean (95% confidence interval) changes in CD4 counts by year-5 CD4 count strata (<500, 500750 and >750 cells/L) of 14 (7 to 21), 3 (5 to 11) and 6 (17 to 4) cells/L/year. Of the CD4 cell count rates of change estimated, none were indicative of long-term declines in CD4 cell counts. Conclusions Our results suggest that duration of cART and increasing age do not result in decreasing mean changes in CD4 cell counts for long-term virologically suppressed patients, indicating that the level of immune recovery achieved during the first 5 years of treatment is sustained through long-term cART.