The healthcare industry in the United States underwent a significant shift in diagnostic coding with the adoption of the ICD-10-CM (International Classification of Diseases, 10th Revision, Clinical Modification) codeset. This transition, mandated by the 2010 Affordable Care Act, replaced the ICD-9-CM system for all HIPAA-regulated transactions, impacting how diagnosis codes are used for laboratory tests, particularly in Medicare billing.
This change became effective on October 1, 2016, following the Preserving Access to Medicare Act of 2014. For those involved in diagnostic clinical laboratory services and Medicare claims, understanding this transition is crucial. Further details regarding the implementation of ICD-10-CM coding can be found at /ICD10.
It’s important to note that the Centers for Medicare & Medicaid Services (CMS) implemented a Partial Code Freeze for both ICD-9-CM and ICD-10 updates from October 1, 2011, through September 30, 2016. Detailed information about this Partial Code Freeze can be accessed at /Medicare/Coding/ICD10/Downloads/Partial_Code_Freeze.pdf (PDF).
To ensure a smooth transition and maintain clinical equivalence between the old and new coding systems, CMS utilized General Equivalence Mappings (GEMs) to facilitate the conversion from ICD-9-CM to ICD-10-CM codes. These GEMs were publicly available through CMS, with the 2018 version being the last one issued. As ICD-10-CM has been in effect for several years, CMS discontinued the use of GEMs after 2018. The final 2018 GEMs are still accessible at /ICD10.
Due to the extensive volume of codes in the October 2018 ICD-10 update, the Medicare shared systems incorporated these new codes in the January 2019 quarterly update. While the system implementation was in January 2019, the effective date for these new ICD-10-CM codes remained October 1, 2018. Critically, all deleted codes became invalid for payment after September 30, 2018. Medicare contractors were instructed to adjust claims as needed to reflect these updates.
