Clinical diagnosis groups developed to bridge the ICD-9-CM to ICD-10-CM coding transition and monitor trends in workers’ compensation claims — Ohio, 2011–2018

Introduction: This study aimed to develop a set of broad clinical diagnosis (ClinDx) groups relevant to occupational safety and health. The ClinDx groups are necessary for analysis and interpretation of longitudinal health data that include injury and disease codes from the Ninth and Tenth Revision of the International Classification of Disease, Clinical Modification (ICD-9-CM, ICD-10-CM). Methods: Claims data were analyzed for Ohio Bureau of Workers’ Compensation insured employers from 2011 to 2018. We used interrupted time series regression models to estimate level (frequency) and slope (trend) changes to the percentage of each ClinDx group in October 2015. We created ClinDx groups aligned with ICD-10-CM structure and coding principles. Each ClinDx group was counted once per claim (distinct groups). Monthly percentages were calculated based on the injury date. When present, seasonality was assessed separately for each outcome using an autoregressive-moving average model. Results: The final set of ClinDx groups included 57 mutually exclusive and exhaustive groups. The study population included 661,684 claims, with 959,322 distinct ClinDx groups. Among all claims, 96.27% included injury code(s) and 11.77% included disease(s) codes. At the transition to ICD-10-CM, 33 ClinDx groups lacked any statistically significant (P < 0.05) changes between periods. We observed level changes for 17 ClinDx groups and slope changes for nine groups. Eight ClinDx groups had ≥ 20% (+/-) level changes. Conclusion: While the transition to ICD-10-CM is a break in series, about two-thirds of disease groups and half of injury groups were relatively stable across the transition. These findings also underscore the need for characterizing both injury and disease outcomes when analyzing workers’ compensation data. Practical Applications: The 57 ClinDx groups created in this study may be a practical starting point for other occupational epidemiologic analyses that include a mixture of ICD-9-CM and ICD-10-CM data.