ICU Versus High-Dependency Care Unit for Patients With Acute Myocardial Infarction: A Nationwide Propensity Score-Matched Cohort Study

Abstract

Objectives: To compare the outcomes of patients with acute myocardial infarction who were treated in ICUs versus high-dependency care units (HDUs). Design: A nationwide, propensity score-matched, retrospective cohort study of a national administrative inpatient database in Japan from July 2010 to March 2018. Setting: Six hundred sixty-six acute-care hospitals with ICU and/or HDU beds covering about 75% of all ICU beds and 70% of all HDU beds in Japan. Patients: Adult patients who were hospitalized for acute myocardial infarction and admitted to the ICU or HDU on the day of hospital admission. Propensity score-matching analysis was performed to compare the inhospital mortality between patients treated in the ICU and HDU on the day of hospital admission. Interventions: ICU or HDU admission on the day of hospital admission. Measurements and Main Results: Of 135,142 eligible patients, 89,382 (66%) were admitted to the ICU and 45,760 (34%) were admitted to the HDU on the day of admission. After propensity score matching, there was no statistically significant difference in inhospital mortality between the ICU and HDU groups (5.0% vs 5.5%; difference, –0.5%; 95% CI, –1.0% to 0.1%). In the subgroup analyses, inhospital mortality was significantly lower in the ICU group than that in the HDU group among patients with Killip class IV (25.6% vs 28.4%; difference, –2.9%; 95% CI, –5.4% to –0.3%), patients who underwent intubation (40.0% vs 46.6%; difference, –6.6%; 95% CI, –10.6% to –2.7%), and patients who received mechanical circulatory support (21.8% vs 24.7%; difference, –2.8%; 95% CI, –5.5% to –0.2%). Conclusions: Critical care in the ICU compared with that in the HDU was not associated with reduced inhospital mortality among the entire cohort of patients with acute myocardial infarction but was associated with reduced inhospital mortality among the subsets of patients with Killip class IV, intubation, or mechanical circulatory support.