A Visual Medication Schedule to Improve Anticoagulation Control: A Randomized, Controlled Trial

Background: Misunderstanding between clinicians and patients may lead to medication-related errors and poor clinical outcomes, particularly in anticoagulant care. Methods: One hundred forty-seven chronic warfarin users were randomized to receive a visual medication schedule at each visit, along with brief counseling, versus standard care, and followed for 90 days. At baseline, patient and clinician reports of the prescribed warfarin regimen were recorded to identify patients as "discordant" versus "concordant" to determine whether the effect of the intervention varied with clinician-patient discordance. Results: At baseline, clinician-patient warfarin regimen discordance was common in intervention and control groups (38% versus 42%). Intervention subjects achieved anticoagulation control more rapidly than control subjects (median 28 versus 42 days; hazard ratio [HR], 1.43; confidence interval [CI], 1.00, 2.06). The benefit of the intervention was significant among subjects with baseline regimen discordance (median, 28 versus 49 days; HR, 1.92; CI, 1.08, 3.39) but not among subjects with baseline concordance (median 28 versus 35 days; HR, 1.14; CI, 0.71,1.83). Discussion: Among patients in poor anticoagulant control whose understanding of their warfarin regimen is discordant with their providers', a visual medication schedule, combined with brief counseling, reduced time to anticoagulation control. The study suggests a simple strategy to enhance medication safety and efficacy for at-risk patients.