CD4 cell response to antiretroviral therapy in children with vertically acquired HIV infection: Is it associated with age at initiation?

Background. Considerable uncertainty remains as to whether early initiation of antiretroviral therapy ( ART) in children with vertically acquired human immunodeficiency virus (HIV) infection increases the benefit in terms of immunological response. Methods. The association between immunological outcome and early initiation of and/or more-potent ART was investigated, using age-standardized z scores for CD4 cell counts ( hereafter, "CD4 z scores"), in 131 HIV-infected children enrolled in the European Collaborative Study, a birth cohort study. Results. Median age at initiation of the most-potent ART was 4 years ( range, 0.1-15.5 years). Initiation of treatment after 5 months of age resulted in nonsignificantly lower CD4 z scores 6 months after initiation. Time to a 20% increase in CD4 z score was associated with age at initiation of the most-potent ART ( adjusted hazard ratios [AHRs], 0.37 [P < .01] and 0.43 [P = .05] for 5 months-5 years of age and > 5 years of age, respectively, compared with < 5 months of age), ethnicity ( AHR, 0.48 [P = .01], for black vs. white), and highly active ART (HAART) with or without prior ART ( AHRs, 3.16 [P < .01] and 3.95 [P < .001], vs. mono or dual ART, respectively). The risk of subsequent deterioration of CD4 z score was similar for children who initiated ART in different age groups (chi(2) = 0.824; P = .82). Conclusions. We confirm the effectiveness of HAART with respect to the recovery of CD4 cell count and suggest a benefit of initiating ART before the age of 5 months. Age at initiation of the most-potent ART was not associated with the likelihood of sustaining the recovery of CD4 cell count.