title: Multicenter study on the value of ICD-9-CM codes for case identification of celiac disease.
abstract: OBJECTIVE
  To evaluate the value of ICD-9-CM code for identifying celiac disease (CD).
  
  
  METHODS
  We searched administrative data to identify all adults with ICD-9-CM diagnosis code 579.0 (CD) at three teaching hospitals between 2000 and 2010. We then stratified patients according to the presence/absence of relevant serology and endoscopy codes into four groups: None, serology, endoscopy, and both. A diagnostic algorithm was applied to define CD status.
  
  
  RESULTS
  Through random sampling and appropriate weighting, the 1200 reviewed patients represented a cohort of 8,122 cases. The overall positive predictive value (PPV) of the ICD-9-CM code was 15% (95% confidence interval [CI], 13%-17%). Case identification by a diagnosis code alone had a PPV of 4%, whereas the group with diagnosis code plus both serology and endoscopy testing had a PPV of 49%. Independent predictors of CD were non-Hispanic white, ICD-9-CM-coded patient group, total number of a diagnosis code, and receiving a diagnosis code by a gastroenterologist. The model had an area under the curve of 0.87 (95% CI, 0.84-0.89).
  
  
  CONCLUSIONS
  The performance of ICD-9-CM 579.0 alone for identifying CD is extremely poor. Adding other readily available administrative data significantly improves CD case identification. The proposed case finding strategy via administrative databases may facilitate future research on CD.
authors: Department of Pediatrics, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA, USA.
authors: Pornthep
authors: P
authors: Tanpowpong
authors: Sarabeth
authors: S
authors: Broder-Fingert
authors: Joshua C
authors: JC
authors: Obuch
authors: David O
authors: DO
authors: Rahni
authors: Aubrey J
authors: AJ
authors: Katz
authors: Daniel A
authors: DA
authors: Leffler
authors: Ciaran P
authors: CP
authors: Kelly
authors: Carlos A
authors: CA
authors: Camargo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002446:Celiac Disease / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology*; D015331:Cohort Studies; D016208:Databases, Factual / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence