Interrupted time series design to evaluate ICD-9-CM to ICD-10-CM coding changes on trends in Colorado emergency department visits related to traumatic brain injury

Abstract Background The transition in 2015 to the Tenth Revision of International Classification Disease, Clinical Modification (ICD-10-CM) US led Centers for Disease Control and Prevention (CDC) propose a surveillance definition traumatic brain injury (TBI) utilizing ICD-10-CM codes. CDC’s proposed excludes “unspecified head,” previously included ICD-9-CM TBI definition. study purpose was evaluate impact change on monthly rates TBI-related emergency department (ED) visits Colorado from 2012 2017. Results rate ED 55.6 per 100,000 persons January 2012. This month (October 2015) decreased by 41 ( p -value < 0.0001), compared September 2015, remained low through December 2017, due exclusion head” (ICD-10-CM code S09.90) average increase 0.33 0.01) prior October 0.04 after. When S09.90 model, smooth no longer significant = 0.97). Conclusion reduction visit resulted CDC excluding unspecified head injury, not necessarily coding itself. Public health practitioners should be aware that could lead drastic magnitude trend visits, which affect decisions regarding allocation resources. highlights challenge creating standardized set codes public provides comparable yet clinically relevant estimates span ICD transition.