Characterization of “ICU‐30”: A Binary Composite Outcome for Neonates With Critical Congenital Heart Disease

Background Neonates with heart disease requiring cardiopulmonary bypass surgery are at high risk for mortality and morbidity. As it is rare, short‐term mortality is difficult to use as a primary outcome for clinical studies. We proposed “ICU‐30” as a binary composite “poor” outcome consisting of: (1) mortality within 30 days, (2) intensive care unit (ICU) admission ≥30 days, or (3) ICU readmission before day 30. To measure the utility of this composite, we assessed its prognostic properties for 6‐ and 12‐month mortality. Methods and Results This was a retrospective single‐center cohort study of neonates requiring cardiopulmonary bypass between 2013 and 2020. Mortality among patients with and without the ICU‐30 outcome was compared using log‐rank tests and Cox regression. Areas under the receiver operating characteristic curves assessed the ability of the composite to predict 12‐month mortality. In 887 neonates, 232 (26.2%) experienced the ICU‐30 outcome, with more prolonged ICU stays and readmissions (both ≥9%) than 30‐day mortality (4.2%). ICU‐30 was associated with higher rates of 6‐ and 12‐month mortality (log‐rank P<0.001) and predicted 12‐month mortality with area under the receiver operating characteristic of 0.81 (95% CI, 0.77–0.85). In 30‐day survivors, both prolonged ICU stay (hazard ratio, 12.3; 95% CI, 6.70–22.7; P<0.001) and ICU readmission (hazard ratio, 2.99; 95% CI, 1.17–7.63; P=0.02) were associated with 12‐month mortality. Conclusions ICU‐30, a composite outcome of mortality, ICU length of stay, or ICU readmission by 30 days was associated with 6‐ and 12‐month mortality in neonates requiring cardiopulmonary bypass. ICU‐30 is captured in routine data collection and appears to be a valid binary patient‐centered outcome.