Misuse of the unspecified coccidioidomycosis diagnosis code: An audit of electronic health records

Widespread use of the 'unspecified coccidioidomycosis' code (B38.9) may negatively impact provider reimbursement and complicate study of disease burden. We sought to determine the frequency of B38.9 use in routine practice and assess how often it could be changed to a more specific code, what code that might be, and reasons for its initial use. To estimate the proportion of all coccidioidomycosis cases that were classified using the International Classification of Diseases-Tenth-Revision unspecified diagnosis code (B38.9), three real-world datasets were queried. Further, in January 2025, providers in coccidioidomycosis-endemic areas were invited to participate in an online electronic health record (EHR) audit to study their three most recent patients coded as B38.9 over the prior 12 months. The proportion of patients that could have received a more specific coccidioidomycosis code by provider was determined, as were the recommended alternative code(s), and reasons for the B38.9's initial use. Across queried datasets, 17.8-49.5% of coccidioidomycosis cases were coded as unspecified. We recruited 19 providers to audit EHRs of 53 patients, in which B38.9 was used. Thirty-six (67.9%) patients could have been assigned a more specific coccidioidomycosis code, including 14 (38.9%) to disseminated disease (B38.7). Common reasons for using B38.9 included evolving clinical assessment (37.0%), lack of coding expertise (22.2%), and entry errors (22.2%). In conclusion, a substantial proportion of coccidioidomycosis diagnoses are assigned to B38.9. Over two-thirds of these could have been better described using a more specific code. There is a need for educational efforts to promote more precise coding.