Abstract 243: ICD-10, DRG and ACTION: Poor Agreement Between Diagnoses of Acute Myocardial Infarction Results in Significant Differences in Process and Outcome Measures

Abstract

Background: In the Unites States, there are three major approaches to identify patients diagnosed with Acute Myocardial Infarction (AMI). The Center for Medicare and Medicaid Services uses ICD-10 codes (1) for the Value-Based Payments program whereas it uses DRG codes (2) for the Inpatient Prospective Payment System. Hospital administrators, meanwhile, often use the NCDR® ACTION Registry® (3) to examine process and outcome measures for their AMI patients. Understanding which patients are captured by these different classification systems, and whether there is agreement between them, has important implications for hospitals’ efforts to optimize performance measures and payments for AMI. Methods: In a retrospective cohort analysis, we examined 730 hospitalizations at the University of Colorado Hospital between January 1, 2017 and October 6, 2018 that were captured by one of the three methods for identifying AMI patients: 1) ICD-10, 2) DRG, or 3) ACTION. Categories were not mutually exclusive. Agreement between DRG, ICD-10 and ACTION diagnoses of AMI was assessed by percentage agreement with the total AMI cohort and dual-comparison kappa statistics. AMI cohorts defined by ICD-10 vs. DRG vs. ACTION were then compared according to the primary outcome of 100-day mortality, as well as secondary outcomes of 30-day readmission, length of stay (LOS), P2Y12 inhibition and rates of inpatient echocardiography. Results: Among 730 hospitalizations with at least one diagnosis of AMI, 617 (84.5%) were assigned a primary ICD-10 code for AMI, 227 (31.1%) were assigned a DRG code for AMI, and 479 (65.6%) carried a diagnosis of AMI in ACTION. Only 112 (15.3%) were captured by all 3 diagnosis groups (ICD-10, DRG and ACTION). 159 (21.7%) hospitalizations were captured by both ICD-10 and DRG diagnoses (Kappa -0.143); 425 (58.2%) were included in ICD-10 and ACTION groups (Kappa 0.141); 121 (16.6%) were included in DRG and ACTION groups (Kappa -0.137). Outcomes and process measures as a function of diagnosis category are presented in Figure 1. Conclusion: Only about 15% of patients with a diagnosis of AMI were included in all three diagnosis groups (ICD-10, DRG and ACTION). There may be significant between-group differences in outcomes and process measures. These data emphasize the need to harmonize administrative definitions for AMI.