PBI40 ICD-9 TO ICD-10 MAPPING FOR RESEARCH IN BIOLOGICS AND BIOSIMILARS USING ADMINISTRATIVE HEALTHCARE DATA

Abstract

In October 2015, the Centers for Medicare and Medicaid Services (CMS) mandated the transition from ICD-9 to ICD-10 codes. Post-marketing surveillance of originator biologics and their corresponding biosimilars by the Biologics & Biosimilars Collective Intelligence Consortium (BBCIC) requires a robust approach to convert ICD-9 to ICD-10 codes used to define study variables. We examined three ICD-9 to ICD-10 mapping methods for health conditions (HCs) of BBCIC’s interest and compared their incidence in BBCIC’s distributed research network (DRN). We applied forward-backward mapping (FBM), using direct links of forward and backward General Equivalence Mappings developed by CMS, to 110 HCs. Secondary mapping (SM) and tertiary mapping (TM), based on iterations of FBM, were tested for 7 selected variables. A physician reviewed the mapped ICD-10 codes from the three methods. Incidence of the 110 HCs defined by ICD-9 versus ICD-10 codes was examined in the DRN during 9/1/2012-3/31/2018. We visually assessed incidence trends before and after October 2015 and used a threshold of 20% level change to examine the performance of ICD-9-to-ICD-10 conversion. Nearly 4 times more ICD-10 codes were mapped by SM and TM compared to FBM. However, the additional codes identified by SM or TM were mostly irrelevant or non-specific. For distinct conditions such as myocardial infarction, SM or TM did not add any ICD-10 codes. Through visual inspection, 22% HCs had inconsistent ICD-9 versus ICD-10 trends; in general, ICD-10 algorithms led to a higher incidence. 15% HCs had an incidence level change greater than +/-20% between ICD-9 and ICD-10 algorithms. FBM is generally the most efficient way to convert ICD-9 to ICD-10 codes, yet manual review of converted ICD-10 codes is recommended even for FBM. No existing guidance is available to compare the performance of ICD-9 versus ICD-10 codes, leading to challenges in empirically determining the quality of conversions.