Predictors of faster virological suppression in early treated infants with perinatal HIV from Europe and Thailand

OBJECTIVE: To identify predictors of faster time to virological suppression among infants starting combination antiretroviral therapy (cART) early in infancy. DESIGN: Cohort study of infants from Europe and Thailand included in studies participating in the European Pregnancy and Paediatric HIV Cohort Collaboration (EPPICC). METHODS: Infants with perinatal HIV starting cART aged <6 months with ≥1 viral load (VL) measurement within 15 months of cART initiation were included. Multivariable interval-censored flexible parametric proportional hazards models were used to assess predictors of faster virological suppression, with timing of suppression assumed to lie in the interval between last VL≥400 and first VL<400copies/ml. RESULTS: Of 420 infants, 59% were female and 56% from Central/Western Europe, 26% UK/Ireland, 15% Eastern Europe and 3% Thailand; 46% and 54% started a boosted protease inhibitor- or non-nucleoside reverse transcriptase inhibitor- based regimen, respectively. At cART initiation, the median age, CD4% and VL were 2.9 (IQR:1.4-4.1) months, 34 (IQR:24-45)% and 5.5 (IQR:4.5-6.0) log10copies/ml, respectively. Overall, an estimated 89% (95%CI:86-92%) achieved virological suppression within 12 months of cART start. In multivariable analysis, younger age (aHR:0.84 per month older; P < 0.001), higher CD4% (aHR:1.11 per 10% higher; P = 0.010) and lower log10 VL (aHR:0.85 per log10 higher; P < 0.001) at cART initiation independently predicted faster virological suppression. CONCLUSION: We observed a significant independent effect of age at cART initiation, even within a narrow 6 months window from birth. These findings support the earliest feasible cART initiation in infants and suggest that early therapy influences key virological and immunological parameters that could have important consequences for long term health.