Hemostatic Outcome Definitions in Pediatric Extracorporeal Membrane Oxygenation: Challenges in Cohorts From Rotterdam (2019-2023) and Melbourne (2016-2022).

Objectives: To determine if a priori standardization of outcome hemostatic definitions alone was adequate to enable useful comparison between two cohorts of pediatric extracorporeal membrane oxygenation (ECMO) patients, managed according to local practice and protocol.

Design: Comparison of two separate prospective cohort studies performed at different centers with standardized outcome definitions agreed upon a priori.

Setting: General and cardiac PICUs at the Royal Children's Hospital (RCH) in Melbourne, Australia, and the Sophia Children's Hospital (SCH) in Rotterdam, The Netherlands.

Patients: Children (0-18 yr old) undergoing ECMO.

Interventions: None.

Measurements and main results: Although outcome definitions were standardized a priori, the interpretation of surgical interventions varied. The SCH study included 47 ECMO runs (September 2019 to April 2023), and the RCH study included 97 ECMO runs (September 2016 to Jan 2022). Significant differences in patient populations were noted. RCH patients biased toward frequent cardiac ECMO indications, central cannulation, and cardiopulmonary bypass before ECMO. The frequency of outcome ascertainment was not standardized.

Conclusions: This international comparison shows that standardizing hemostatic outcome definitions alone is insufficient for sensible comparison. Uniform interpretation of definitions, consistent frequency of outcome ascertainment, and stratification based on patient populations and ECMO practices are required. Our results highlight the granularity of detail needed for cross-center comparison of hemostatic outcomes in pediatric ECMO. Further work is needed as we move toward potential multicenter trials of pediatric ECMO.