title: Assessment of text documentation accompanying uncoded diagnoses in computerized health insurance claims in Japan.
abstract: BACKGROUND
  Uncoded diagnoses in health insurance claims (HICs) may introduce bias into Japanese health statistics dependent on computerized HICs. This study's aim was to identify the causes and characteristics of uncoded diagnoses.
  
  
  METHODS
  Uncoded diagnoses from computerized HICs (outpatient, inpatient, and the diagnosis procedure-combination per-diem payment system [DPC/PDPS]) submitted to the National Health Insurance Organization of Kumamoto Prefecture in May 2010 were analyzed. The text documentation accompanying the uncoded diagnoses was used to classify diagnoses in accordance with the International Classification of Diseases-10 (ICD-10). The text documentation was also classified into four categories using the standard descriptions of diagnoses defined in the master files of the computerized HIC system: 1) standard descriptions of diagnoses, 2) standard descriptions with a modifier, 3) non-standard descriptions of diagnoses, and 4) unclassifiable text documentation. Using these classifications, the proportions of uncoded diagnoses by ICD-10 disease category were calculated.
  
  
  RESULTS
  Of the uncoded diagnoses analyzed (n = 363 753), non-standard descriptions of diagnoses for outpatient, inpatient, and DPC/PDPS HICs comprised 12.1%, 14.6%, and 1.0% of uncoded diagnoses, respectively. The proportion of uncoded diagnoses with standard descriptions with a modifier for Diseases of the eye and adnexa was significantly higher than the overall proportion of uncoded diagnoses among every HIC type.
  
  
  CONCLUSIONS
  The pattern of uncoded diagnoses differed by HIC type and disease category. Evaluating the proportion of uncoded diagnoses in all medical facilities and developing effective coding methods for diagnoses with modifiers, prefixes, and suffixes should reduce number of uncoded diagnoses in computerized HICs and improve the quality of HIC databases.
authors.affiliation: Department of Public Health and Preventive Medicine, School of Medicine, Fukuoka University.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tanihara
mesh_terms: D059019:Clinical Coding / Q000706:statistics & numerical data*; D003933:Diagnosis; D004282:Documentation; D006801:Humans; D007344:Insurance Claim Reporting / Q000706:statistics & numerical data*; D007345:Insurance Claim Review; D007348:Insurance, Health; D038801:International Classification of Diseases; D007564:Japan