Effectiveness of CHA₂DS₂-VASc based decision support on stroke prevention in atrial fibrillation: A cluster randomised trial in general practice

Background: Guidelines on atrial fibrillation (AF) recommend the CHA₂DS₂-VASc rule for anticoagulant decision-making, but underuse exists. We studied the impact of an automated decision support on stroke prevention in patients with AF in a cluster randomised trial in general practice. Methods: Intervention practices were provided with a CHA₂DS₂-VASc based anticoagulant treatment recommendation. Reference practices provided care as usual. The primary outcome was incidence of ischaemic stroke, transient ischaemic attack (TIA) and/or thromboembolism (TE). Secondary outcomes were bleeding and the proportion of patients on guideline recommended anticoagulant treatment. Results: In total, 1129 AF patients were included in the 19 intervention practices and 1226 AF patients in the 19 reference practices. The median age was 77 (interquartile range (IQR) 68–75) years, the median CHA₂DS₂-VASc score was 3.0 (IQR 2.0–5.0). Underuse of anticoagulants in patients with CHA₂DS₂-VASc score ≥ 2 was 6.6%. After a median follow-up of 2.7 years (IQR 2.3–3.0), the incidence rate per 100 person-years of ischaemic stroke/TIA/TE was 1.96 in the intervention group and 1.42 in the reference group (hazard ratio (HR) 1.3, 95% C.I. 0.8–2.1). No difference was observed in the rate of bleeding (0.79 versus 0.82), or in the underuse (7.2% versus 8.2%) or overuse (8.0% versus 7.9%) of anticoagulation. Conclusions: In this study in patients with AF in general practice, underuse of anticoagulants was relatively low. Providing practitioners with CHA₂DS₂-VASc based decision support did not result in a reduction in stroke incidence, affect bleeding risk or anticoagulant over- or underuse.