Association between age at antiretroviral therapy initiation and 24-month immune response in West-African HIV-infected children.

OBJECTIVE: We describe the association between age at antiretroviral therapy (ART) initiation and 24-month CD4 cell response in West African HIV-infected children.
METHODS: All HIV-infected children from the IeDEA paediatric West African cohort, initiating ART, with at least two CD4 cell count measurements, including one at ART initiation (baseline) were included. CD4 cell gain on ART was estimated using a multivariable linear mixed model adjusted for baseline variables: age, CD4 cell count, sex, first-line ART regimen. Kaplan-Meier survival curves and a Cox proportional hazards regression model compared immune recovery for age within 24 months post-ART.
RESULTS: Of the 4808 children initiated on ART, 3014 were enrolled at a median age of 5.6 years; 61.2% were immunodeficient. After 12 months, children at least 4 years at baseline had significantly lower CD4 cell gains compared with children less than 2 years, the reference group (P<0.001). However, by 24 months, we observed higher CD4 cell gain in children who initiated ART between 3 and 4 years compared with those less than 2 years (P<0.001). The 24-month CD4 cell gain was also strongest in immunodeficient children at baseline. Among these children, 75% reached immune recovery: 12-month rates were significantly highest in all those aged 2-5 years at ART initiation compared with those less than 2 years. Beyond 12 months on ART, immune recovery was significantly lower in children initiated more than 5 years (adjusted hazard ratio: 0.69, 95% confidence interval: 0.56-0.86).
CONCLUSION: These results suggest that both the initiation of ART at the earliest age less than 5 years and before any severe immunodeficiency is needed for improving 24-month immune recovery on ART.