title: Computer-assisted expert case definition in electronic health records.
abstract: OBJECTIVE
  To describe how computer-assisted presentation of case data can lead experts to infer machine-implementable rules for case definition in electronic health records. As an illustration the technique has been applied to obtain a definition of acute liver dysfunction (ALD) in persons with inflammatory bowel disease (IBD).
  
  
  METHODS
  The technique consists of repeatedly sampling new batches of case candidates from an enriched pool of persons meeting presumed minimal inclusion criteria, classifying the candidates by a machine-implementable candidate rule and by a human expert, and then updating the rule so that it captures new distinctions introduced by the expert. Iteration continues until an update results in an acceptably small number of changes to form a final case definition.
  
  
  RESULTS
  The technique was applied to structured data and terms derived by natural language processing from text records in 29,336 adults with IBD. Over three rounds the technique led to rules with increasing predictive value, as the experts identified exceptions, and increasing sensitivity, as the experts identified missing inclusion criteria. In the final rule inclusion and exclusion terms were often keyed to an ALD onset date. When compared against clinical review in an independent test round, the derived final case definition had a sensitivity of 92% and a positive predictive value of 79%.
  
  
  CONCLUSIONS
  An iterative technique of machine-supported expert review can yield a case definition that accommodates available data, incorporates pre-existing medical knowledge, is transparent and is open to continuous improvement. The expert updates to rules may be informative in themselves. In this limited setting, the final case definition for ALD performed better than previous, published attempts using expert definitions.
authors.affiliation: WHISCON, Newton, MA 02466, USA. Electronic address: AlecWalker@WHISCON.com.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Walker
authors.affiliation: Epidemiology, Research and Development, Worldwide Safety and Regulatory, Pfizer, New York, NY 10017, USA.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Division of Gastroenterology, Crohn's and Colitis Center, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Ashwin N
authors.initials: AN
authors.lastname: Ananthakrishnan
authors.affiliation: Epidemiology, Research and Development, Worldwide Safety and Regulatory, Pfizer, New York, NY 10017, USA.
authors.forename: Lisa S
authors.initials: LS
authors.lastname: Weiss
authors.affiliation: Epidemiology, Research and Development, Worldwide Safety and Regulatory, Pfizer, New York, NY 10017, USA.
authors.forename: Rongjun
authors.initials: R
authors.lastname: Shen
authors.affiliation: Epidemiology, Research and Development, Worldwide Safety and Regulatory, Pfizer, New York, NY 10017, USA.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Sobel
authors.affiliation: Epidemiology, Research and Development, Worldwide Safety and Regulatory, Pfizer, New York, NY 10017, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Bate
authors.affiliation: Epidemiology, Research and Development, Worldwide Safety and Regulatory, Pfizer, New York, NY 10017, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Reynolds
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003936:Diagnosis, Computer-Assisted; D057286:Electronic Health Records / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008107:Liver Diseases / Q000175:diagnosis*; D008297:Male; D008490:Medical Informatics; D008875:Middle Aged; D009323:Natural Language Processing; D055815:Young Adult
keywords: Case definition; Electronic health records; Health outcomes; Insurance claims data; Safety surveillance