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.