Preparing for ICD-10-CM/PCS: one payer's experience with general equivalence mappings (GEMs).

The International Classification of Diseases, Tenth Edition, Clinical Modification/Procedure Coding System (ICD-10-CM/PCS) has been mandated as the new code set to be used for medical coding in the United States beginning on October 1, 2013, replacing the use of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). To assist in the transition from ICD-9-CM to ICD-10-CM/PCS, the National Center for Health Statistics developed bidirectional general equivalent mappings (GEMs) between the old and new code sets. This article looks at how the GEMs have been leveraged by Health Care Service Corporation (HCSC) to achieve the goal of transition to ICD-10-CM/PCS. The analysis examines the questions asked and lessons learned in the practical application of the GEMs for the translation of business rules and processes in order to promote a deeper understanding of the data issues involved in the transition from ICD-9-CM to ICD-10-CM/PCS from a payer's perspective.