Comparing Outcomes of a Rapid High-Sensitivity Troponin Protocol Between Hospital-Based and Freestanding Emergency Departments

Abstract

Study objectives: Significant variability exists in patient populations and diagnostic capabilities among hospital-based emergency departments (HBEDs) and freestanding emergency departments (FSEDs). While high sensitivity cardiac troponin (hs-cTn) research has focused on HBEDs, its application in FSEDs remains unexplored. This study assesses the comparative, real-world effectiveness of a 0/1-h accelerated protocol (AP) using hs-cTn between HBEDs and FSEDs.

Methods: We conducted a pre-planned, secondary analysis of a stepped-wedge cluster randomized trial involving nine EDs within an integrated health system, from July 2020 to March 2021, comprised of five HBEDs and four FSEDs. The trial implemented a 0/1-h AP utilizing hs-cTnI to evaluate acute myocardial infarction (AMI). Adult ED patients with an ECG and cardiac troponin ordered were eligible, excluding those with STEMI, hs-cTnI > 18 ng/L, or trauma-related symptoms. The primary outcome was safe ED discharge, defined as discharge without death or AMI within 30 days.

Results: The trial included 32,609 patients, 26,957 in HBEDs and 5652 in FSEDs. Safe discharge from HBED occurred 53.7% (5935/11,062) of the time in the standard care arm and 50.3% (7991/15895) under the AP (aOR 1.04, 95% CI 0.94-1.15, p = 0.50). Safe discharge from a FSED occurred 86.0% (2102/2443) of the time in the standard care arm and increased to 95.0% (3049/3209) under the AP (aOR 1.48, 95% CI 1.03-2.13, p = 0.033). Overall, the observed association between the AP and safe discharge was stronger in FSEDs than in HBEDs ( $\Delta$ log(aOdds) 1.05, 95% CI (0.82, 1.29), p < 0.001).

Conclusion: Implementing a 0/1-h AP using hs-cTnI to evaluate for AMI was associated with higher rates of safe discharge in FSEDs compared to HBEDs.