Emergency Department Volume and Outcomes for Patients After Chest Pain Assessment

BACKGROUND: Chest pain is one of the most common reasons for emergency department (ED) visits in developed countries. Whether higher volume EDs have better outcomes, specifically for patients with chest pain, is unknown and pertinent. METHODS AND RESULTS: We conducted a study using population-based data on 498 291 patients >= 40 years old, presenting to ED in Ontario, Canada from 2008 to 2014, with chest pain and were discharged after assessment. We evaluated processes of care after discharge from ED. The primary outcome was a composite of all-cause death or hospitalization for acute coronary syndrome. Hierarchical logistic regression models adjusting for potential confounding variables were used to evaluate the association of annual ED chest pain volume and outcome. We also determined if there was a volume threshold above which an increased ED volume was not associated with a lower adverse outcome. The mean age of our patients was 59 years, 46.7% were men, and 20% had diabetes mellitus. Patients discharged from higher volume EDs had higher rates of cardiologist consultations, cardiac medication use, and cardiac testing within 30 days of ED assessment. Higher ED volume was associated with significantly lower adjusted odds ratio for mortality or acute coronary syndrome (odds ratio, 0.87; 95% Cl, 0.82-0.92 per each unit increase in the log of volume) at 30 days and at 1 year (odds ratio, 0.92; 95% Cl, 0.88-0.92). Once the annual ED chest pain volume reached 1400 cases (95% Cl, 910-1900), an increase of annual chest pain volume of 100 was associated with relative decrease in the odds of the composite outcome at 30 days of <1%. CONCLUSIONS: Evaluations of chest pain in EDs with higher chest pain volume had lower rates of death or hospitalizations for acute coronary syndrome. There was a volume threshold above which an increase in volume was no longer associated with reduced outcomes.