title: ICD-10-CM Crosswalks in the primary care setting: assessing reliability of the GEMs and reimbursement mappings.
abstract: OBJECTIVE
  The general equivalence mappings (GEMs) and reimbursement mappings (RMs) facilitate translation between ICD-9-CM and ICD-10-CM. This study compared prospectively dual-encoded diagnoses assigned by professional coders with the GEMs/RMs in a clinical setting.
  
  
  METHODS
  Professional coders manually encoded diagnoses from 100 primary care notes into both ICD-9-CM and ICD-10-CM. The investigators evaluated whether manual mappings were reproducible using the GEMs/RMs. Reproducible mappings with one ICD-9-CM and one ICD-10-CM code ("one-to-one") were classified as exact or approximate using GEMs flags. Mismatches were characterized manually.
  
  
  RESULTS
  Manual encodings were reproducible from the forward GEMs, backward GEMs, and RMs in 85.2%, 90.4%, and 88.1% of diagnoses, respectively. For one-to-one, reproducible mappings, 61% (forward) and 63% (backward) were approximate mappings compared to 85% and 95% in the GEMs as a whole. Mismatches between manual and GEMs encodings were due to differences in coder interpretation (11%-13%), subtle hierarchical differences (52%-55%), or unknown reasons (32%-35%).
  
  
  CONCLUSIONS
  This study highlights inconsistencies between manual encoding and using the GEMs/RMs. The number of approximate mappings in our population compared to all one-to-one GEMs entries supports the notion that statistics describing the GEMs as a whole might not represent the most important mappings for each organization. The mismatch characteristics highlight the subtle differences between manual encoding and using the GEMs/RMs.
  
  
  CONCLUSIONS
  These results support the need for organizations to assess the GEMs and RMs in their own environment to avoid changes in reimbursement and longitudinal statistics.
authors: Vanderbilt University School of Medicine, Nashville, TN, USA.
authors: Robert W
authors: RW
authors: Turer
authors: Health Informatics Technologies and Services, Vanderbilt University Medical Center, Nashville, TN, USA.
authors: Theresa D
authors: TD
authors: Zuckowsky
authors: Select Specialty Hospital, Nashville, TN, USA.
authors: H Jennifer
authors: HJ
authors: Causey
authors: Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA trent.rosenbloom@vanderbilt.edu.
authors: S Trent
authors: ST
authors: Rosenbloom
mesh_terms: D059019:Clinical Coding / Q000379:methods*; D006801:Humans; D007349:Insurance, Health, Reimbursement / Q000706:statistics & numerical data; D038801:International Classification of Diseases; D011320:Primary Health Care; D015203:Reproducibility of Results
keywords: GEMs; General Equivalence Mappings; ICD-10-CM; ICD-9-CM; International Classification of Diseases; Reimbursement Mappings