Does caffeine prevent hypoxaemic episodes in premature infants? A randomized controlled trial. Caffeine for Apnea of Prematurity trial: benefits may vary in subgroups.
Fifty spontaneously breathing, preterm infants 48 h old, of 32 weeks' gestation or less, were assigned randomly to receive caffeine citrate (loading dose 20 mg/kg, maintenance dose 10 mg/kg per day) or a placebo (NaCl 0.9%). The study hypothesis was that caffeine reduces the proportion of infants with recurrent hypoxaemic episodes (decrease in transcutaneous PO2 of 20% within 20 s) from 50% to 25%. Transcutaneous oxygen tension (tcPO2) and heart rate were recorded continuously for 50 h and analysed by computer. The two groups were similar in gestational age, birth weight, delivery mode, sex distribution, and Apgar scores. The mean serum concentration (+/- SD) of caffeine 2 h after the second maintenance dose was 96.0 (+/- 34.5) mumol/l in the group receiving caffeine and 9.3 (+/- 12.8) mumol/l in the group receiving a placebo. The mean proportion of infants with more than six hypoxaemic episodes per 12 h in the caffeine groups was higher (57%) than in the control group (51%). The mean proportion of infants with more than six episodes of bradycardia per 12 h was not statistically different in the caffeine group (79%) from the control group (86%). Our results suggest that prophylactic caffeine has little if any effect on the risk of developing hypoxaemic episodes and bradycardia in small preterm infants and the supposed 50% reduction which was considered clinically important at the start of the trial can be rejected with confidence. To determine whether the benefits of caffeine vary in three subgroups of 2006 participants in the Caffeine for Apnea of Prematurity (CAP) trial.
                Post-hoc subgroup analyses were performed on the basis of: (1) indication for commencement of study drug: treat apnea, prevent apnea, or facilitate extubation; (2) positive pressure ventilation (PPV) at randomization: endotracheal tube (ETT), noninvasive ventilation, or none; and (3) timing of commencement of study drug: early or late (< or =3 versus >3 days). Outcomes assessed were those showing treatment effects in the original analyses. We investigated the consistency of caffeine effects by using regression models that incorporated treatment/subgroup factor interactions.
                There was little evidence of a differential treatment effect of caffeine in subgroups defined by the clinical indication for starting study drug. The size and direction of the caffeine effect on death or disability differed depending on PPV at randomization (P = .03). Odds ratios (95% CI) were: no support, 1.32 (0.81-2.14); noninvasive support, 0.73 (0.52-1.03); and ETT, 0.73 (0.57-0.94). Adjustment for baseline factors strengthened this effect (P = .02). Starting caffeine early resulted in larger reductions in days of respiratory support. Postmenstrual age at time of discontinuing PPV was shorter with earlier treatment (P = .01). Mean differences (95% CI) were: early, 1.35 weeks (0.90-1.81); and late 0.55 weeks (-0.11-0.99). Adjustment for baseline factors weakened this effect (P = .03).
                There is evidence of variable beneficial effects of caffeine. Infants receiving respiratory support appeared to derive more neurodevelopmental benefits from caffeine than infants not receiving support. Earlier initiation of caffeine may be associated with a greater reduction in time on ventilation.
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