Objective: Within Emergency Medical Systems (EMS) regional systems, there may be significant differences in the approach to patient care despite efforts to promote standardization. Identifying hospital-level factors that contribute to variations in care can provide opportunities to improve patient outcomes. The purpose of this analysis was to evaluate variation in post-cardiac arrest care within a large EMS system and explore the contribution of hospital-level factors. Methods: This was a retrospective analysis from a regional cardiac system serving over 10 million persons. Patients with out-of-hospital cardiac arrest (OHCA) with return of spontaneous circulation (ROSC) are transported to 36 cardiac arrest centers with 24/7 emergent coronary angiography (CAG) capabilities and targeted temperature management (TTM) policies based on regional guidelines. We included adult patients ≥18 years with non-traumatic OHCA from 2016-2018. Patients with a Do-Not-Resuscitate order and those who died in the emergency department (ED) were excluded. For the TTM analysis, we also excluded patients who were alert in the ED. The primary outcome was receiving CAG or TTM after cardiac arrest. The secondary outcome was neurologic recovery (dichotomized to define a "good" outcome as cerebral performance category (CPC) 1 or 2). We used generalized estimating equations including patient-level factors (age, sex, witnessed arrest, initial rhythm) and hospital-level factors (academic status, hospital size based on licensed beds, annual OHCA patient volume) to estimate the odds ratios associated with these variables. Results: There were 7831 patients with OHCA during the study period; 4694 were analyzed for CAG and 3903 for TTM. The median and range for treatment with CAG and TTM after OHCA was 23% (12-49%) and 58% (17-92%) respectively. Hospital size was associated with increased likelihood of CAG, adjusted odds ratio 1.71, 95% CI 1.05-2.86, p = 0.03. Academic status approached significance in its association with TTM, adjusted odds ratio 1.69, 95% CI 0.98-2.91, p = 0.06. Overall, 28% of patients survived with good neurologic outcome, ranging from 17 to 43% across hospitals. Conclusion: Within this regional cardiac system, there was significant variation in use of CAG and TTM after OHCA, which was not fully explained by patient-level factors. Hospital size was associated with increased CAG.
Keywords: emergency medical services; heart arrest; hypothermia; induced; percutaneous coronary intervention.