Why is warfarin underused for stroke prevention in atrial fibrillation? A detailed review of electronic medical records

Objective: Automated electronic queries of structured data fields in electronic medical records (EMR) found no barriers to warfarin in 42 of patients with atrial fibrillation or atrial flutter (AF) with moderate or high risk of stroke and no warfarin. A thorough manual review of records (including text reports) from the same EMR may better identify physicians' reasons for not using warfarin. Methods: This was a cross-sectional, retrospective, manual EMR review. Patients identified in a previous automated EMR study with a CHADS2 (Chronic heart failure, Hypertension, Age >75 years, Diabetes mellitus, Stroke) score 2, no record of warfarin, no barrier to warfarin use, and (in the present study) confirmation of AF diagnosis were included in the manual EMR review. A structured chart abstraction form was used to extract data visible in the clinicians' EMR user interface. Reasons why warfarin had not been prescribed were reported using descriptive statistics. Results: Among 408 patients with 'no barriers' to warfarin in the automated EMR review, AF diagnosis was confirmed in 319 patients (mean age 74.8; 65 female). Forty-one percent (n=132) did not have chart records explaining why they were not on warfarin. Among the 59 (187) with a rationale against warfarin found in the records, the most common category (52) was indicative of the risk of bleeding, either risk of fall or history of recent bleeding. The second most common category (16) reflected that the patient was back in sinus rhythm. These findings are subject to inherent limitations of retrospective chart reviews. Conclusions: Many patients with AF and moderate-to-high risk of stroke are not treated with warfarin, and reasons for not using warfarin could not always be identified in patient records. Among patients with documented reasons, risk of bleeding (risk of fall or recent bleeding) was the most common category.