International classification of diseases and current procedural terminology codes underestimated thrombolytic use for ischemic stroke

Background and Objective: To determine the accuracy of recently introduced International Classification of Diseases Ninth Revision (ICD-9) procedure and Current Procedural Terminology (CPT) codes designed for injection or infusion of thrombolytic agents. Materials and Methods: We determined the accuracy of ICD-9 procedure code 99.10 and CPT codes 37201, 37202 for use of thrombolysis in ischemic stroke by comparing procedure codes of University Hospital discharge data with a concurrent prospective registry. Results: Of the 369 ischemic stroke patients, 49 (13.3%) received either intravenous and/or intraarterial thrombolysis. The sensitivity and specificity for ICD-9 procedure code 99.10 was 55% and 98% and CPT procedure code 37201 and 37202 was 49% and 99%. Identification by either ICD-9 codes or CPT codes yielded a high sensitivity and specificity of 82% and 98%. Conclusions: The use of ICD-9 and CPT codes alone may underestimate the use of thrombolytics using national and regional database. Best results are achieved when a combination of ICD-9 and CPT codes are used to identify the use of thrombolytics.