ICD-10 Codes for the Study of Chronic Overlapping Pain Conditions in Administrative Databases

Chronic overlapping pain conditions (COPCs) are a set of painful chronic conditions characterized by high levels of co-occurrence. It has been hypothesized that COPCs co-occur in many cases because of common neurobiological vulnerabilities. In practice, most research on COPCs has focused upon a single index condition with little effort to assess comorbid painful conditions. This likely means that important phenotypic differences within a sample are obscured. The International Classification of Diseases (ICD) coding system contains many diagnostic classifications that may be applied to individual COPCs, but there is currently no agreed upon set of codes for identifying and studying each of the COPCs. Here we seek to address this issue through three related projects 1) we first compile a set of ICD-10 codes from expert panels for ten common COPCs, 2) we then use natural language searches of medical records to validate the presence of COPCs in association with the proposed expert codes, 3) finally, we apply the resulting codes to a large administrative medical database to derive estimates of overlap between the ten conditions as a demonstration project. The codes presented can facilitate administrative database research on COPCs. PERSPECTIVE: This article presents a set of ICD-10 codes that researchers can use to explore the presence and overlap of COPCs in administrative databases. This may serve as a tool for estimating samples for research, exploring comorbidities, and treatments for individual COPCs, and identifying mechanisms associated with their overlap.