Converting Data to ICD- 10 with GEMs
Reference Mapping Tools Will Aid in System Transition
By Theresa Rihanek, RHIA, CCS, and Kathy DeVault, RHIA, CCS, CCS-P
MANY HEALTHCARE ORGANIZATIONS use historical coded ata in governance and planning activities, contracting, qual- ity improvement, research, and trending. The upcoming imple- mentation of ICD-10-CM/PCS will require organizations to identify the types of coded data that will require conversion in order for these functions to continue in a meaningful way. Or- ganizations may elect to handle the conversion process either internally by using the General Equivalence Mappings (GEMs), or they may choose to outsource this work instead. GEMs are reference mapping tools that can be used to con- vert data from ICD-9-CM to ICD-10-CM/PCS or vice versa. The mappings were developed in an attempt to include all valid
relationships between the codes in ICD-9-CM and in ICD-10-
CM/PCS classifications, as well as to ensure that consistency in
national data is maintained.
GEM files attempt to organize the differences in the two code
sets in a meaningful way. The GEMs link a code to all valid alternatives in the other code set from which choices can be made
depending upon the use of the code. One code set may not be
able to seamlessly link to identical counterparts in the other
set. It is often difficult with ICD-9-CM and ICD-10-CM/PCS to
find two corresponding descriptions that are identical in level of
specificity and terminology. This is to be expected, since there
would be no point in moving from the old system to the new if
the differences between the two—and the resulting benefits—
were not significant.
The GEMs are public domain, general purpose reference mappings designed to benefit all sectors of the healthcare industry
that use coded data by providing them with the tools to:
x Convert large databases and test system applications
x Link data in long-term clinical studies
x Develop application-specific mappings
x Analyze data collected before and after the transition to
Those involved with the data-conversion project will require
education on the GEMs, mapping processes, and related tech-
nology. Organizations will need to assess the impact that the
transition to ICD-10-CM/PCS will have on their longitudinal
data analysis. To determine this impact, they should address the
If there is a decision to develop application-specific mappings,
additional questions regarding map validity arise.
x Will legacy data need to be converted?
x If so, what data needs to be converted?
x How will it be converted?
x If coded data is mapped using the GEMs, will application-
specific mappings need to be developed?
x What data will be mapped using an application-specific
x What data will be maintained separately?
x What are the benefits of mapping the data?
x What are the risks if data mapping is not completed?