Comparison of Diagnostic Accuracy for Lower-Extremity Amputation Codes During the ICD-9 and ICD-10 Eras in a High-Risk Population of Patients With Diabetes.

Abstract

In fiscal year (FY) 2016, the U.S. transitioned to the ICD-10, which includes eight times more amputation procedure codes than the ICD-9. To evaluate trends over time, researchers need assurance that differences over time are not influenced by a change in the coding system. Thus, we aimed to compare the diagnostic accuracy for ascertaining amputations performed during the ICD-9 era compared with during the ICD-10 era, using medical record review as a gold standard. This information will be valuable for others who use electronic health records to study lower-extremity amputation and whose data span this transition. The source population was veterans who had a procedure code (ICD or Current Procedural Terminology [CPT]) for an initial toe or ray amputation (hereafter referred to as toe amputations) between FY 2005 and FY 2016 and a diagnosis of diabetes or prescription for a diabetes medication in the year prior to their toe amputation (1). We randomly sampled 150 veterans from the parent study (1) who had initial toe amputations in FY 2014 and follow-up through the end of FY 2015 (during the ICD-9 era) and 150 veterans who had initial toe amputations in FY 2016 (during the ICD-10 era). The outcome of interest was an ipsilateral amputation (at any level) in the year after the toe amputation. Procedure codes were extracted from the Veterans Affairs (VA) Corporate Data Warehouse, which includes data from the VA electronic medical record. To maximize sensitivity for the parent study, we relied on both ICD and CPT codes for identification …