Variation in Critical Care Unit Admission Rates and Outcomes for Patients With Acute Coronary Syndromes or Heart Failure Among High‐ and Low‐Volume Cardiac Hospitals

Abstract

Background Little is known about cross‐hospital differences in critical care units admission rates and related resource utilization and outcomes among patients hospitalized with acute coronary syndromes ( ACS ) or heart failure ( HF ). Methods and Results Using a population‐based sample of 16 078 patients admitted to a critical care unit with a primary diagnosis of ACS (n=14 610) or HF (n=1467) between April 1, 2003 and March 31, 2013 in Alberta, Canada, we stratified hospitals into high (>250), medium (200 to 250), or low (<200) volume based on their annual volume of all ACS and HF hospitalization. The percentage of hospitalized patients admitted to critical care units varied across low, medium, and high‐volume hospitals for both ACS and HF as follows: 77.9%, 81.3%, and 76.3% ( P <0.001), and 18.0%, 16.3%, and 13.0% ( P <0.001), respectively. Compared to low‐volume units, critical care patients with ACS and HF admitted to high‐volume hospitals had shorter mean critical care stays (56.6 versus 95.6 hours, P <0.001), more critical care procedures (1.9 versus 1.2 per patient, <0.001), and higher resource‐intensive weighting (2.8 versus 1.5, P <0.001). No differences in in‐hospital mortality (5.5% versus 6.2%, adjusted odds ratio 0.93; 95% CI , 0.61 to 1.41) were observed between high‐ and low‐volume hospitals; however, 30‐day cardiovascular readmissions (4.6% versus 6.8%, odds ratio 0.77; 95% CI , 0.60 to 0.99) and cardiovascular emergency‐room visits (6.6% versus 9.5%, odds ratio 0.80; 95% CI , 0.69 to 0.94) were lower in high‐volume compared to low‐volume hospitals. Outcomes stratified by ACS or HF admission diagnosis were similar. Conclusions Cardiac patients hospitalized in low‐volume hospitals were more frequently admitted to critical care units and had longer hospitals stays despite lower resource‐intensive weighting. These findings may provide opportunities to standardize critical care utilization for ACS and HF patients across high‐ and low‐volume hospitals.