Increasing cooling duration in comatose survivors of out-of-hospital cardiac arrest (OHCA) being treated with therapeutic hypothermia did not improve neurological outcomes, according to findings from the multicenter, randomized ICECAP trial published in JAMA.

William J. Meurer, MD, MS, et al., enrolled 1,158 patients (median age 61 years, 40% female) who suffered OHCA undergoing therapeutic hypothermia at 33°C. The first 200 patients were randomized to cooling durations of 12, 24 and 48 hours. The rest of the participants were assigned via a response-adaptive randomization algorithm to cooling durations between 6 and 72 hours. The study's primary outcome was neurological function at 90 days, measured by a weighted modified Rankin Scale score.

The trial reached a prespecified stopping rule at an interim analysis. The posterior probability of six hours being the shortest duration that achieves the maximal mean weighted modified Rankin Scale score was 0.51 among patients with nonshockable rhythms (n=883) and 0.49 among those with shockable rhythms (n=275).

No significant differences in neuropsychological test outcomes or mortality were seen across cooling durations.

"The results of the current study demonstrate that increasing cooling duration, as performed and evaluated in this trial in broadly representative and inclusive cohorts of patients after OHCA, does not improve outcomes," state the authors.