Reliability of patient‐reported outcome measures: Hemorrhage, anticoagulant, antiplatelet medication use

BACKGROUND: Most antithrombotic medication users are older adults. Patient‐reported outcome measures are commonly used in clinical research on antithrombotic medication, such as the diagnosis of intracranial hemorrhage. OBJECTIVES: To determine the reliability of patient‐reported intracranial hemorrhage, anticoagulant and platelet aggregation inhibitor use in the older adult population. PATIENTS/METHODS: We conducted a secondary analysis of a prospective, observational cohort study of older adults who presented to the emergency department with a fall. The primary outcome was diagnosis of intracranial bleeding. We compared patient‐reported intracranial bleeding to structured chart review with adjudication. We also compared patient‐reported use of antiplatelet and anticoagulant medication to physician‐reported medication use supplemented with structured chart review. We calculated the diagnostic accuracy of the patient‐reported outcomes using our comparators as the reference standard. RESULTS: Exact agreement for patient‐reported intracranial bleeds was 95%, with a Cohen’s kappa of 0.30 (95% confidence interval [CI], 0.15‐0.45). The sensitivity was 36.7% (95% CI, 20.6%‐56.1%) and specificity 97.2% (95% CI, 95.8%‐98.1%). For anticoagulant medication use, exact agreement was 87%, Cohen’s kappa 0.66 (95% CI, 0.63‐0.72), sensitivity 84.0% (95% CI, 79.3%‐83.8%), and specificity 87.6% (95% CI, 85.1%‐89.7%). For antiplatelet medication use, exact agreement was 77%, Cohen’s kappa 0.50 (95% CI, 0.44‐0.55), sensitivity 68.7% (95% CI, 64.0%‐73.1%), and specificity 81.2% (95% CI, 78.0‐83.8%). CONCLUSIONS: Patient‐reported outcome and exposure data were unreliable in this study. Our findings have a bearing on future research study design.