ImportanceOral anticoagulation for adults with atrial fibrillation or atrial flutter (AFF) who are at elevated stroke risk reduces the incidence of ischemic stroke but remains underused. Efforts to increase anticoagulation initiation on emergency department (ED) discharge have yielded conflicting results.ObjectiveTo evaluate the effectiveness of a multipronged intervention supporting anticoagulation initiation for eligible adult ED patients.Design, Setting, and ParticipantsThe Clinical Decision Support to Optimize Care of Patients With Atrial Fibrillation or Flutter in the Emergency Department (O’CAFÉ) pragmatic, stepped-wedge cluster randomized clinical trial was conducted from July 1, 2021, through April 30, 2023, at 13 community medical centers (in 9 clusters) of an integrated health system in Northern California. The study included adult ED patients with primary AFF eligible for anticoagulation initiation when discharged home. Clusters were randomly assigned to staggered dates for 1-way crossover from the control phase (usual care) to the intervention phase.InterventionPhysician education, facility-specific audit and feedback, and access to decision support, which identified eligible patients and recommended shared decision-making, anticoagulation initiation (if suitable), and timely follow-up.Main Outcomes and MeasuresThe main outcome was a composite of anticoagulation on discharge or within 30 days. A primary intention-to-treat analysis (decision support access regardless of use) and a secondary per-protocol analysis (decision support use) were performed. Multivariable analyses adjusted for intervention and exposure months with random effects, accounting for clustering by facility and patient.ResultsA total of 3388 eligible patients with atrial fibrillation were discharged home: 2185 (64.5%) were receiving pre-ED arrival anticoagulation and 1203 (35.5%) were eligible for anticoagulation. Among the 1203 patients with an initiation-eligible encounter, the median age was 74.0 (IQR, 68.0-82.0) years and approximately half (618 [51.4%]) were men. Among the 387 patients with an initiation-eligible control encounter, 244 (63.0%) received anticoagulation (190 [49.0%] at discharge and 54 [14.0%] within 30 days). Among the 816 patients with an initiation-eligible intervention encounter, 558 (68.4%) received anticoagulation (428 [52.5%] on discharge and 130 [15.9%] within 30 days). There was no statistically significant change in initiation of anticoagulation associated with the intervention (adjusted odds ratio, 1.33 [95% CI, 0.75-2.35]; P = .13). Decision support was used for 217 eligible case patients (26.6%) (per protocol) and was associated with a statistically significant change in anticoagulation initiation when compared with 599 patients for whom decision support was not used (164 [75.6%] vs 394 [65.8%]; P = .008).Conclusions and RelevanceIn this trial, a multipronged intervention to facilitate thromboprophylaxis among eligible ED patients with AFF did not significantly increase anticoagulation initiation. Opportunities exist to further improve stroke prevention among ED patients with primary AFF.Trial RegistrationClinicalTrials.gov Identifier: NCT05009225
