General Equivalence Mappings (GEMs)
The General Equivalence Mappings (GEMs) are a tool that can be used to convert data from ICD-9-CM to ICD-10-CM and PCS and vice versa. The GEMs are the product of a coordinated effort spanning several years and involving the National Center for Health Statistics (NCHS), the Centers for Medicare and Medicaid Services (CMS), AHIMA, the American Hospital Association, and 3M Health Information Systems. The GEM files are a public domain reference mapping designed to give all sectors of the healthcare industry that use coded data a tool to convert and test systems, link data in long-term clinical studies, develop application-specific mappings, and analyze data collected during the transition period and beyond.
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