title: Using patients like my patient for clinical decision support: institution-specific probability of celiac disease diagnosis using simplified near-neighbor classification.
abstract: BACKGROUND
  Interpretation of a diagnostic test result requires knowing what proportion of patients with a "similar" result has the condition in question. This information is often not readily available from the medical literature, or may be based on different clinical populations that make it nonapplicable. In certain settings, where correlated screening parameters and diagnostic data are available in electronic medical records, a representation of diagnostic test performance on "patients like my patient" can be obtained.
  
  
  OBJECTIVE
  We sought to integrate patient demographic and physician practice information using a simplified nearest neighbor algorithm. We used this method to illustrate the relationship between tTG IgA test result and duodenal biopsy for celiac disease in a local diagnostic context.
  
  
  METHODS
  We used a data set of 1,461 paired tissue transglutaminase (tTG) IgA and definitive duodenal biopsy results from Intermountain Healthcare with data on patient age and ordering physician specialty. This was split into a discovery set of 1,000 and a validation set of 461 paired results.
  
  
  METHODS
  Accuracy of the local discovery data set in predicting probability of positive duodenal biopsy and confidence intervals around predicted probability in the test data compared to probabilities of positive biopsy implied from published logistic regression and from published sensitivity and specificity studies.
  
  
  RESULTS
  The near-neighbor method could estimate probability of clinical outcomes with predictive performance equivalent to other methods while adjusting probability estimates and confidence intervals to fit specific clinical situations.
  
  
  CONCLUSIONS
  Data from clinical encounters obtained from electronic medical records can yield prediction estimates that are tailored to the individual patient, local population, and healthcare delivery processes. Local analysis of diagnostic probability may be more clinically meaningful than probabilities inferred from published studies. This local utility may come at the expense of external validity and generalizability.
authors: Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA, shirtsb@uw.edu.
authors: Brian H
authors: BH
authors: Shirts
authors: Sterling T
authors: ST
authors: Bennett
authors: Brian R
authors: BR
authors: Jackson
mesh_terms: D000293:Adolescent; D000465:Algorithms; D002446:Celiac Disease / Q000097:blood* / Q000175:diagnosis*; D020000:Decision Support Systems, Clinical / Q000592:standards; D019204:GTP-Binding Proteins / Q000097:blood; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D008875:Middle Aged; D015233:Models, Statistical; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D012189:Retrospective Studies; D011503:Transglutaminases / Q000097:blood; D055815:Young Adult
chemical_list: D007070:Immunoglobulin A; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins
references: Am J Gastroenterol. 2010 Dec;105(12):2520-4
references: 21131921
references: J Pediatr Gastroenterol Nutr. 2012 Feb;54(2):229-41
references: 22266486
references: Endoscopy. 2008 Mar;40(3):219-24
references: 18058655
references: Nat Methods. 2011 Jun;8(6):487-93
references: 21516115
references: J Clin Gastroenterol. 2012 Feb;46(2):e12-20
references: 21959324
references: Int J Biomed Comput. 1995 Apr;39(1):151-6
references: 7601529
references: N Engl J Med. 2010 Jul 1;363(1):45-53
references: 20463332
references: Clin Gastroenterol Hepatol. 2008 Mar;6(3):314-20
references: 18328437
references: World J Gastroenterol. 2009 Oct 14;15(38):4775-80
references: 19824110
references: AMIA Annu Symp Proc. 2008 Nov 06;:535-9
references: 18998878
references: J Clin Gastroenterol. 2008 Mar;42(3):256-60
references: 18223500
references: J Clin Pathol. 2012 Mar;65(3):242-7
references: 22081783
references: Pediatrics. 2005 May;115(5):1341-6
references: 15867045
references: JAMA. 2010 May 5;303(17):1738-46
references: 20442390
references: J Gen Intern Med. 2012 Oct;27(10):1361-7
references: 22618581
references: J Pediatr Gastroenterol Nutr. 2012 Jan;54(1):136-60
references: 22197856
references: J Am Med Inform Assoc. 2012 Mar-Apr;19(2):263-74
references: 21984587
references: Clin Chem Lab Med. 2010 May;48(5):685-91
references: 20201743
references: Ann Intern Med. 1989 Nov 1;111(9):751-6
references: 2802433
references: Am J Gastroenterol. 2010 Sep;105(9):2103-10
references: 20372112
references: Clin Rev Allergy Immunol. 2012 Jun;42(3):331-41
references: 21279475
references: Cochrane Database Syst Rev. 2010 May 12;(5):CD006732
references: 20464744