A Bayesian Interpretation of a Pediatric Cardiac Arrest Trial (THAPCA-OH)

Abstract

BackgroundPediatric out-of-hospital cardiac arrest results in high morbidity and mortality. Currently, there are no recommended therapies beyond supportive care. The THAPCA-OH (Therapeutic Hypothermia after Pediatric Cardiac Arrest Out-of-Hospital) trial compared hypothermia (33.0°C) with normothermia (36.8°C) in 295 children. Good neurobehavioral outcome and survival at 1 year were higher in the hypothermia group (20 vs. 12% and 38 vs. 29%, respectively). These differences did not meet the planned statistical threshold of P<0.05. To ensure that a potentially efficacious therapy is not prematurely discarded, we reassessed THAPCA-OH using a Bayesian statistical perspective.MethodsWe performed a Bayesian analysis, interpreting the trial in probabilistic terms (i.e., the probability that therapeutic hypothermia had any benefit, and overall absolute improvements greater than 2%, 5%, and 10% for 1-year neurobehavioral outcome and survival). Our primary analyses used noninformative priors, meaning that the analyses were based on the observed trial data without any information added by the priors. In the absence of pediatric trials to derive informative prior distributions, we used: (1) downweighted priors from adult trials; and (2) a previously published set of critical care priors that span benefit, equipoise, and harm.ResultsIn the primary analyses, the probability of any benefit from hypothermia was 94% for both the neurobehavioral outcome and survival at 1 year. For both outcomes, the probability of benefit was >75% for all informative prior integrations with the THAPCA-OH results, except those with the most pessimistic priors.ConclusionsThere is a high probability that hypothermia provides a modest benefit in neurobehavioral outcome and survival at 1 year. (ClinicalTrials.gov number, NCT00878644.)