Re-purposing the ICD-9-CM Procedures Index for Coding in ICD-10-PCS and SNOMED CT

Compared to the ICD-10-PCS index, the ICD-9-CM Procedure (ICD9V3) Index is richer and contains more clinician-friendly terms including abbreviations and eponyms. We re-purposed the ICD9V3 index by mapping the index terms to SNOMED CT and the ICD-9-CM codes to ICD-10-PCS codes through the General Equivalent Mappings. The re-purposed index outperformed the ICD-10-PCS index in the retrieval of ICD-10-PCS codes using a list of commonly used procedure names, with significantly higher recall, precision and F-score. We also derived a SNOMED CT to ICD-10-PCS map from the re-purposed ICD-9-CM index, which had a higher coverage of SNOMED CT concepts and comparable accuracy compared to a map derived from the ICD-10-PCS index. The re-purposed index will be a useful resource for ICD-10-PCS coders and for mapping between SNOMED CT and ICD-10-PCS.