Because patient care, revenue cycle transactions, quality monitoring, and reporting must continue during the transition, staff need a road map to use in bridging ICD-9 data to ICD-10 via a transparent methodology. Thus tools were created to assist the healthcare industry with the conversion from ICD-9 to ICD-10.   

GEMs. CMS has published the General Equivalence Mappings (GEMs), which are four text files that contain bi-directional mappings for both diagnoses and procedures (ICD-9 to ICD-10 and ICD-10 to ICD-9).  The mappings contain all the clinically plausible translation alternatives from one code set to another, including one-to-one, one-to-many and many-to-one mappings. They are meant to be a general purpose aid to help vendors, payers, providers, and reporting agencies convert their existing ICD-9 based systems to ICD-10.

The GEMs can be employed in a variety of ways, such as linking ICD-9 and ICD-10 data for long-term clinical studies and analyzing data collected during the ICD-10 transition period and beyond. 

Reimbursement Mappings. The Reimbursement Mappings, released by CMS in December 2008, offer a single recommended mapping of each ICD-10 code to a single ICD-9-CM alternative. This crosswalk is based on MS-DRGs and can be used to help prepare billing systems for the transition and to support the phase-out of ICD-9-based systems after Oct. 1, 2013, when healthcare claims will be submitted to payers using ICD-10 diagnosis codes and, for inpatient services only, ICD-10-PCS procedure codes.

Although CMS will be converting its systems to use ICD-10 codes directly after the 2013 implementation date, some payers that use coded data in financial applications may still be working through the conversion process and dependent on ICD-9-CM-based legacy systems at that time. Reimbursement Mappings provide a temporary mechanism for converting records containing ICD-10 codes into "reimbursement equivalent" records containing ICD-9-CM diagnosis and procedure codes, so that while systems are being converted to process I-10 claims directly, the ICD-10 claims may be processed by the ICD-9 legacy claims processing systems.

More information about using the mapping tools is available from CMS, the National Center for Health Statistics (NCHS), and AHIMA. 

Using the GEM Tool

The following table shows examples of diagnosis mapping from ICD-9-CM to ICD-10-CM and whether there is a one-to-one equivalence. The mapping tools correlate every diagnosis and procedure from ICD-10-CM to ICD-9-CM. The GEMs can expose opportunities to capture finer distinctions in ICD-10-CM that may be reimbursed differently in the future, but that can be used by facilities now to more accurately track resource utilization and other measures.

Diagnosis Equivalences Table

Publication Date: Friday, January 01, 2010

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