Assessing the Utility and Accuracy of ICD10-CM Nontraumatic Subarachnoid Hemorrhage Codes for Intracranial Aneurysm Research

BackgroundThe 10th revision of International Classification of Disease, Clinical Modification (ICD10-CM) increased the number of codes to identify nontraumatic subarachnoid hemorrhage from one to twenty-two. ICD10-CM codes are able to specify the location of aneurysms causing subarachnoid hemorrhage (aSAH), however it is not clear how frequently or accurately these codes are being used in practice. ObjectiveTo systematically evaluate the usage and accuracy of location-specific ICD10-CM codes for aSAH. MethodsWe extracted all uses of ICD10-CM codes for nontraumatic subarachnoid hemorrhage (I60.x) during the first three years following the implementation of ICD10-CM from the billing module of the EHR for UCHealth. For those codes that specified aSAH location (I60.0-I60.6), EHR documentation was reviewed to determine whether there was an active aSAH, any patient history of aSAH, or unruptured intracranial aneurysm/s and the locations of those outcomes. ResultsBetween October 1, 2015 - September 30, 2018, there were 3,119 instances of nontraumatic subarachnoid hemorrhage ICD10-CM codes (I60.00-I60.9), of which 297 (9.5%) code instances identified aSAH location (I60.0-I60.6). These codes accurately identified current aSAH (64%), any patient history of aSAH (84%), and any patient history of intracranial aneurysm (87%). The accuracy of identified outcome location was 53% in current aSAH, 72% for any history of aSAH, and 76% for any history of an intracranial artery. ConclusionsResearchers should use ICD10-CM codes with caution when attempting to detect active aSAH and/or aneurysm location.