title: Self-reported awareness and use of the International Classification of Diseases coding of inflammatory bowel disease services by Ontario physicians.
abstract: BACKGROUND
  Population and health services research can be performed by linkage analysis of administrative data. However, the robustness of study results is determined by the accuracy of the diagnostic coding.
  
  
  OBJECTIVE
  To estimate the awareness, use and accuracy of the International Classification of Diseases, Ninth Revision (ICD-9) coding by physicians providing services for patients with Crohn's disease (CD) and ulcerative colitis (UC).
  
  
  METHODS
  All Ontario gastroenterologists and a 10% random sample of internists, pediatricians, pediatric or general surgeons, and family physicians were surveyed by postal questionnaire to estimate the frequency and 95% CI of using codes 555 or 556 when billing for CD- and UC-related services, respectively. c2 tests were used for between-group comparisons.
  
  
  RESULTS
  Of the physicians who were surveyed, 67.7% (416 of 614) responded; 258 of 391 (66%) who were still practising in Ontario saw patients with inflammatory bowel disease (IBD), and 54% had more than 10 IBD patients; 86.5% (95% CI 82.4% to 90.6%) were familiar with ICD-9 codes, and 91.4% (95% CI 88.1% to 95.6%) used the codes 555 (CD) or 556 (UC) for billing. Rates of ICD-9 use did not differ by sex but were used more frequently by those graduating after 1981 (P<0.02). Gastroenterologists used ICD-9 IBD codes 555 or 556 significantly more often than all other physicians (P=0.001). Most (more than 75%) Ontario physicians used ICD-9 IBD codes always or frequently when billing for IBD-related services. Few (10%) used these codes to bill for non-IBD-related problems.
  
  
  CONCLUSIONS
  These data suggest that there is acceptable use and accuracy of ICD-9 diagnostic coding for CD and UC services - comparable with results from studies of other diseases. Administrative data may thus be used to undertake epidemiological studies in IBD in Ontario.
authors.affiliation: McMaster University, Hamilton, Canada.
authors.forename: Forough
authors.initials: F
authors.lastname: Farrokhyar
authors.forename: Kevin
authors.initials: K
authors.lastname: McHugh
authors.forename: E Jan
authors.initials: EJ
authors.lastname: Irvine
mesh_terms: D001364:Awareness; D003093:Colitis, Ulcerative / Q000175:diagnosis; D003424:Crohn Disease / Q000175:diagnosis; D003953:Diagnosis-Related Groups; D006751:Hospital Information Systems; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis*; D038801:International Classification of Diseases / Q000706:statistics & numerical data*; D009864:Ontario; D010820:Physicians; D012042:Registries / Q000706:statistics & numerical data; D012647:Self-Assessment; D011795:Surveys and Questionnaires