There are limited data on infants
starting antiretroviral therapy (ART) in the neonatal period. We investigated the association between the timing of ART initiation and time-to-suppression among infants
who tested HIV
-positive and initiated ART within the first 28 days of life. The effect was estimated using cumulative probability flexible parametric spline models and a multivariable generalized additive mixed model was performed to test nonlinear associations. Forty-four neonates
were included. Nineteen (43.2%) initiated ART within 7 days of life and 25 (56.8%) from 8 to 28 days. Infants
treated within 7 days were 4-fold more likely to suppress earlier than those treated after 7 days [Hazard ratio (HR) 4.01 (1.7–9.5)]. For each week the ART initiation was delayed, the probability of suppression decreased by 35% (HR 0.65 [0.46–0.92]). Age at ART start was linearly associated with time-to-suppression. However, a linear association with normally distributed residuals was not found between baseline viral load
and time-to-suppression, with no association found when baseline viral loads were ≤5 log(10) copies/mL, but with exponential increase in time-to-suppression with > log5 copies/mL at baseline. Starting ART within 7 days of life led to 4-fold faster time to viral suppression
, in comparison to initiation from 8 to 28 days.