Medical Coding, 2nd Edition

APPENDIX B

General Equivalence Mapping (GEM) Files

The vast differences between ICD-9-CM and ICD-10-CM/PCS pose major challenges for many players in the healthcare arena. Providers and payers have to change their billing and claims processing systems. Researchers, public health administrators, actuaries, and others who rely on historical coded data have to be able to convert data from one system to the other. A need was also identified for a temporary “fix” that could be used in the transition period leading up to October 1, 2015, to run parallel databases and identify potential adverse effects of the change to ICD-10-CM/PCS. To address these issues, over a period of 3 years the Centers for Medicare and Medicaid Services (CMS) and the Centers ...