Objective: To assess the effect of aging on the immunological response to antiretroviral therapy (ART) in the West African context.
Methods: The change in CD4 T-cell count was analysed according to age at the time of ART initiation among HIV-infected patients enrolled in the International epidemiological Database to Evaluate AIDS (IeDEA) Collaboration in the West African region. CD4 gain over 12 months of ART was estimated using linear mixed models. Models were adjusted for baseline CD4 cell count, sex, baseline clinical stage, calendar period and ART regimen.
Results: The total number of patients included was 24,107, contributing for 50,893 measures of CD4 cell count in the first year of ART. The baseline median CD4 cell count was 144 cells/μl [interquartile range (IQR) 61-235]; median CD4 cell count reached 310 cells/μl (IQR 204-443) after 1 year of ART. The median age at treatment initiation was 36.3 years (10th-90th percentiles = 26.5-50.1). In adjusted analysis, the mean CD4 gain was significantly higher in younger patients (P < 0.0001). At 12 months, patients below 30 years recovered an additional 22 cells/μl on average [95% confidence interval (CI) 2-43] compared to patients at least 50 years.
Conclusion: Among HIV-infected adults in West Africa, the immunological response after 12 months of ART was significantly poorer in elderly patients. As the population of treated patients is likely to get older, the impact of this age effect on immunological response to ART may increase over time.