The importance of establishing regimen concordance in preventing medication errors in anticoagulant care

Miscommunication between patients and providers can have serious consequences, especially where medications are concerned. We examined whether regimen discordance between patient and provider, a possible result of miscommunication, contributes to unsafe medication management. We studied 220 patients taking warfarin in an anticoagulation clinic to characterize two medication assessment methods. We measured (1) adherence by asking patients to report any missed doses and (2) concordance between patients' and providers' reports of warfarin regimens. We categorized patients as having regimen adherence if they missed no doses, and concordance if there was patient-provider agreement in weekly dosage. We characterized anticoagulant outcomes as unsafe if international normalized ratio (INR) values were <2.0 (at risk for thrombosis) or >4.0 (at risk for hemorrhage), and explored relationships among adherence, concordance, and anticoagulant outcomes. One hundred fifty-five patients (71%) reported no missed doses during the prior 30 days. Poor adherence was associated with underanticoagulation (AOR 2.33, 1.56-3.45), but not overanticoagulation (AOR 1.36, 0.69-2.66). One hundred ten patients (50%) reported regimens discordant with clinicians' report. There was no relationship between patients' reports of adherence and concordance. Among adherent patients, discordance was associated with underanticoagulation (AOR 1.67, 1.00-2.78) and overanticoagulation (AOR 3.44, 1.32-9.09). Discordance regarding warfarin regimens is common and places patients at risk for adverse events. To promote safe and effective care, clinicians should separately determine adherence and regimen concordance during routine medication assessments. Systems need to be developed to ensure concordance in medication regimens.