Abstract 75: Validation of Vascular Location Subcodes for Acute Ischemic Stroke by the International Classification of Diseases-10

Abstract

Background: The affected vascular region is included in the International Classification of Diseases-10 (ICD-10) coding scheme for stroke. These data have the potential to enable studies of vascular and regional location. For example, differentiating anterior versus posterior circulation stroke. However, the coding in real world practice has not been validated. The purpose of this study was to evaluate the validity of these subcodes. Methods: We identified all hospitalizations for ischemic stroke at a single center from 2018-2022. We selected a random sample of 100 hospitalizations with vascular region subcoding specifying 50 with anterior circulation subcodes (carotid, anterior cerebral artery [CA], middle CA) and 50 with posterior circulation subcodes (vertebral, basilar, cerebellar, posterior CA). The gold standard classification for the primary infarct vascular distribution was made by the study team, blinded to the subcode, after review of the available imaging studies and the medical record. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the administrative data posterior circulation subcodes versus anterior circulation subcodes with the gold standard classification. We also calculated the kappa statistic for overall agreement of the 7 vascular regions. Results: The final study population was 50 ICD-10 anterior circulation ischemic stroke hospitalizations and 50 ICD-10 posterior circulation ischemic stroke hospitalizations. Mean age was 68 (SD, 15) and 44% (44/100) were female. Mean NIHSS was 8 (SD, 8). Neuroimaging was performed in 100% (100/100): Head CT, 95% (95/100); MRI brain, 77% (77/100). The accuracy of the ICD-10 classification for primary posterior circulation stroke was as follows: sensitivity 89% (49/55); specificity 98% (44/45); PPV 98% (49/50); NPV 88% (44/50), respectively. The reliability of the 7-region classification was excellent (kappa statistic, 0.85). Conclusions: We found that the ICD-10 subcode classification for vascular location used in clinical practice had excellent agreement with our gold standard based on medical review. These data validate the use of these subcodes for anterior versus posterior circulation stroke studies.