Individualized Treatment Effects of Therapeutic Hypothermia in Children Postcardiac Arrest: A Reanalysis of Two Randomized Clinical Trials.

OBJECTIVES

To use patient characteristics to estimate individualized treatment effects (ITE) of hypothermia vs. normothermia after pediatric cardiac arrest.

DESIGN

Secondary, exploratory analysis of two pediatric randomized controlled trials (RCTs), Therapeutic Hypothermia after Pediatric Cardiac Arrest Out-of-Hospital (THAPCA-OH; NCT00878644) and Therapeutic Hypothermia after Pediatric Cardiac Arrest Out-of-Hospital In-Hospital (THAPCA-IH; NCT00880087), using a causal forest machine learning model to estimate ITEs within each trial.

SETTING

THAPCA-OH was conducted at 38 children's hospitals across the United States and Canada. THAPCA-IH was conducted at 37 children's hospitals across the United States, Canada, and the United Kingdom.

PATIENTS: Pediatric patients aged 48 hours to 18 years who remained comatose within 6 hours after return of circulation following cardiac arrest and were randomized in THAPCA-OH and THAPCA-IH to normothermia or therapeutic hypothermia for 48 hours. Patients with a baseline Vineland Adaptive Behavior Scales, Second Edition (VABS-II) score less than 70 were excluded.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN

RESULTS

The final cohorts included 260 patients in THAPCA-OH and 257 in THAPCA-IH. The primary outcome was survival at 1 year with VABS-II greater than or equal to 70 (favorable outcome). In THAPCA-OH, estimated ITEs (calculated as the individualized absolute risk difference [iARD] between hypothermia and normothermia, positive favoring hypothermia) ranged from -0.01 to 0.16. Patients were grouped into tertiles of estimated ITE within each trial. In THAPCA-OH, the tertile with the greatest estimated benefit from hypothermia had an observed absolute risk difference (ARD; hypothermia minus normothermia) of 0.18 (95% CI, 0.02-0.34). In THAPCA-IH, estimated ITEs ranged from -0.17 to 0.13. The tertile estimated to benefit most from hypothermia had an ARD of 0.27 (95% CI, 0.07-0.48), whereas the tertile estimated to benefit from normothermia had an ARD of -0.20 (95% CI, -0.40 to -0.01).

CONCLUSIONS

These analyses suggest heterogeneity of treatment effect may exist in postcardiac arrest temperature management warranting further study.