Coders who are still struggling to transition from ICD-9 to ICD-10 will soon have one fewer tool at their disposal. Since the US officially implemented ICD-10 in 2015, the Centers for Medicare and Medicaid Services (CMS) have routinely published a list of general equivalence mappings, more commonly known as GEMs files. These lists helped track the differences between the two coding sets, thereby allowing people familiar with ICD-9 to see exactly how it led into its replacement.

Even when ICD-10 became the official coding set, CMS distributed these GEMs files and allowed dual coding during the first year of the transition in order to ease coders into the change. From there, CMS continued to update the files through 2018 so that coders could have plenty of time to get accustomed to the massive update.

Unfortunately for anyone who still used GEMs files, CMS has announced that it will no longer keep them updated starting with the 2019 coding year. While this may hardly come as a surprise to those who have been deeply entrenched in ICD-10 for years now, this decision has the potential to impact two different groups. On one hand, those who like to look into the history of codes and see how they developed over time will no longer have the convenience of seeing the direct link between ICD-10 and its predecessor. They will, however, still be able to review the 2018 version.

The other group involves anyone who plans to rejoin the coding workforce after a significant absence. While those who have been continuously coding will have long since adapted to ICD-10, coders who have not worked in the field since before the transition will have their work cut out for them when reviewing the litany of changes. Anybody familiar only with ICD-9 should take the loss of GEMS files into account and plan to explore the extensive ICD-10 differences another way.