Accuracy of posthospitalization stroke detection following carotid revascularization in Medicare claims.

Background: Stroke after carotid revascularization is a key effectiveness and quality metric relevant to patients, clinicians, and policymakers. To date, the accuracy of stroke rates reported from Medicare claims-based datasets for patients who underwent carotid revascularization remain unknown. The objective of this study was to validate the accuracy of using International Classification of Diseases, Tenth Revision (ICD-10) codes to detect stroke after carotid artery revascularization.

Methods: We retrospectively reviewed all patients who underwent carotid revascularization at two institutions from January 2016 to December 2019. We used a list of ICD-10 codes to detect stroke that we derived previously and validated in two prospective cohorts with atherosclerosis. We applied the list to all patients who underwent carotid revascularization at the two institutions to identify patients with an ICD-10 code for stroke, either as the indication for the index procedure or after the procedure. We then performed a comprehensive medical record review for all stroke patients, as well as a 1:1 random sample of patients who underwent revascularization during the same time interval and did not have an ICD-10 code for stroke. Our primary outcome was the sensitivity and specificity of the ICD-10 codes to detect posthospitalization stroke (ie, after the index hospitalization) compared with a gold standard of chart review.

Results: We performed a comprehensive medical record review of a cohort oversampled for stroke that included 199 patients (mean age, 73.5±7.6 years; 62.3% male; 95.0% non-Hispanic White; 61.8% symptomatic) who underwent carotid revascularization during the study interval. The majority of patients underwent carotid endarterectomy (82.4%), followed by transcarotid artery revascularization (12.1%) and transfemoral carotid artery stenting (5.5%). Twelve patients had a stroke during their index hospitalization, creating a final cohort of 187 patients eligible for assessment of posthospitalization stroke. After a median follow-up time of 453 days (interquartile range, 82-803 days), 10 asymptomatic patients and 10 symptomatic patients had a posthospitalization stroke based on chart review. Among asymptomatic patients, the sensitivity and specificity of ICD-10 codes to detect a posthospitalization stroke were 100% (95% CI, 69.2%-100.0%) and 96.8% (95% CI, 88.8%-99.6%), respectively, when considering all linked diagnosis codes. Among symptomatic patients, the sensitivity and specificity of ICD-10 codes to detect a posthospitalization stroke were 80.0% (95% CI, 44.4%-97.5%) and 94.3% (95% CI, 88.0%-97.9%), respectively, when considering all diagnosis codes.

Conclusions: Posthospitalization stroke can be measured accurately after carotid revascularization using ICD-10 codes in Medicare claims data. The reliability of the algorithm is better among asymptomatic patients than symptomatic patients.