Emergency Department Management of Atrial Fibrillation in the United States Versus Ontario, Canada

Abstract

Survey data suggest that there is considerable international variation in the emergency department (ED) management of patients with atrial fibrillation (AF) (1–3). Hospitalization is common in the United States (2), where nearly 70% of ED visits for AF end in hospitalization (2,3); this has remained constant since 2000 (2,3). By comparison, in Canada’s most populous province <40% of individual AF patients were admitted in 2010 (1), which had dropped by 10% since 2002 (1). However, no direct intercountry comparisons have been published. Our objective was to directly compare ED AF visits and their associated management strategies in the United States and the province of Ontario, Canada. We conducted a cross-sectional study of ED visits with a primary diagnosis of AF between January 1, 2007, and December 31, 2009, in the U.S. Nationwide Emergency Department Sample (NEDS) and the Canadian Institute for Health Information National Ambulatory Care Reporting System (CIHI-NACRS). The U.S. cohort was defined in NEDS as visits made by patients ages ≥18 years old with the primary (first) ED diagnosis listed as AF, identified by the International Classification of Diseases, Ninth Revision (ICD-9) Clinical Modification code 427.31. The Ontario cohort was defined as ED visits made by patients ages ≥18 years old with the primary ED diagnosis listed as AF, identified by the ICD-10 code I480 in CIHI-NACRS. Ontario has 13 million residents and is the only Canadian province with complete ED data in CIHI-NACRS. The methods for measuring comorbidities and ED cardioversions have been previously described (1,2). The primary outcome measure was the proportion of ED AF visits that resulted in hospitalization in the United States versus Ontario. Secondary outcomes included deaths in the ED and ED cardioversions in the United States versus Ontario. Rate ratios (RR) were used to compare outcomes in the United States and Ontario using the Ontario cohort as the referent. There were an estimated 1,320,123 ED visits for AF in the United States, and 56,413 visits in Ontario. ED visits for AF resulted in hospitalization nearly twice as often in the United States, compared with the Ontario cohort (RR: 1.86; 95% confidence interval [CI]: 1.84 to 1.89). The greatest intercountry differences in hospitalization were among patients <65 years old (Table 1). In the United States, these patients had a similar likelihood of hospitalization as their older U.S. counterparts, whereas the younger cohort in Ontario was far less likely to be hospitalized than older patients. ED deaths were rare in both settings, whereas ED cardioversions were nearly one-half as frequent in the United States (RR: 0.53, 95% CI: 0.51 to 0.54). Older patients are at increased risk of death following the ED visit for AF compared with younger patients, which may justify the need for hospitalization. The rationale behind admitting the majority of younger patients with AF, however, is less evident. Hospitalizations constitute the large majority of the total cost of AF management (4). In addition to exposing patients to the risk of hospital-associated complications, the financial costs of admission are both tremendous and not obviously justified. Differences in the financial incentives (and disincentives) for hospitals to admit low-risk patients in the United States and Canada may contribute to the variation in hospitalization. Future studies are needed to examine the etiologies. TABLE 1 Characteristics of Patients Making ED Visits for AF, in the United States and Ontario, Canada This work used large national and provincial administrative databases; although it facilitates national comparisons, it is subject to limitations. Our evaluation of comorbidities relies on the NEDS site administrators to record these diseases in the remaining 14 diagnoses fields. This increases the potential for underreporting, which may have contributed to the lower levels of prior stroke, as well as other comorbidities, in the U.S. cohort. NEDS has no data on medications or outcomes after the patient is discharged from hospital. The proportion of ED visits for AF that result in hospitalization was almost double in the United States compared with Canada’s most populous province, with the greatest intercountry differences among visits made by patients <65 years old. There is substantial variation between countries in the ED management of AF: such intercountry comparisons represent a first step toward reducing unnecessary hospitalizations, and in turn promoting responsible healthcare resource utilization.