Moving Beyond International Classification of Diseases Codes for the Retrospective Identification of Gender Diverse Veterans.

Purpose: The Veterans Health Administration (VHA) systematically asks Veterans to self-report gender identity for documentation in their electronic health record. Veterans with transgender and gender diverse (TGD) identities experience higher rates of several health conditions compared to Veterans without minoritized gender identities. Historically, cohorts of TGD Veterans were built with International Classification of Diseases Version 10 (ICD-10) codes assigned during clinical encounters. We examined concordance between self-reported gender identity and relevant ICD-10 codes in VHA health records to inform use of these indicators for examining the health needs of TGD Veterans. Methods: TGD-related ICD-10 codes were compared to self-reported gender identity from more than 1.5 million Veterans (2019-2022). Results: Only 34% of TGD Veterans included through self-report had an ICD-10 code associated with transgender care. ICD-10 codes had low sensitivity and high specificity compared to self-reported gender. Conclusion: These findings suggest ICD-10 codes alone undercount the larger population of TGD Veterans in the VHA.