Technical Report 31: Updating the Psychiatric Case Mix System (PsyCMS) Mental Health and Substance Use Grouper for ICD-10-CM

Wagner TH, Gehlert E, Rosen A, Valenstein M. Technical Report 31: Updating the Psychiatric Case Mix System (PsyCMS) Mental Health and Substance Use Grouper for ICD-10-CM. Menlo Park, CA: HERC; 2016 Aug 1. 4 p. Report No.: 31.

Risk-adjustment tools are invaluable in health services research because they allow us to control for clinical heterogeneity in the population that would otherwise bias our analyses of costs, quality and outcomes. In 2014, the United States Department of Veterans Affairs (VA) Office of Productivity, Efficiency and Staffing and the VA Health Economics Resource Center (HERC) jointly developed a new risk-adjustment system for VA cost data. The new system, Nosos, which means 'chronic condition' in Greek, is based on the Centers for Medicare and Medicaid Services (CMS) Hierarchical Condition Categories (HCC) version 21 (V21) risk adjustment system. However, to make the V21 system more robust and suited to the VA population, Nosos includes additional variables important in classifying the VA population: race, marital status, non-VA health insurance status, Veteran's priority level status, VA registry status, VA drug class and 46 psychiatric case mix system (PsyCMS) condition categories, developed by Rosen and colleagues (Montez-Rath et al. 2006; Sloan et al. 2006). PsyCMS was designed using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes from all Veterans who used VA healthcare services during the federal fiscal year 1999 (FY99). On October 1, 2015, all United States healthcare systems were required to begin using the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM). This report describes the methods HERC used to update PsyCMS with ICD-10-CM codes. Section 2 presents the methods used to update the PsyCMS coding scheme and Section 3 presents the final coding scheme.