title: Improving accuracy of International Classification of Diseases codes for venous thromboembolism in administrative data.
abstract: BACKGROUND
  Increasingly, clinicians and researchers are using administrative data for clinical and outcomes research. However, they continue to question the accuracy of using International Classification of Diseases 9th Revision (ICD-9) codes alone to capture diagnoses, especially venous thromboembolism (VTE), in administrative data.
  
  
  OBJECTIVE
  We tested the hypothesis that incorporation of treatment data and/or common procedural terminology (CPT) codes could improve accuracy of administrative data in detecting VTE. Research Design Using the Veterans Affairs Central Cancer Registry, we compared three competing algorithms by performing three cross-sectional studies. Algorithm 1 identified patients by ICD-9 codes alone. Algorithm 2 required VTE treatment in addition to ICD-9 codes. Algorithm 3 required a VTE diagnostic CPT code in addition to treatment and ICD-9 criteria.
  
  
  RESULTS
  The accuracy of ICD-9 codes alone for detection of VTE was marginal, with a PPV of 72%. The PPV was improved to 91% after addition of treatment data (algorithm 2). As compared to algorithm 2, addition of CPT codes (algorithm 3) did not significantly increase the accuracy of detecting VTE (PPV 92%), but decreased sensitivity from 72% to 67%.
  
  
  CONCLUSIONS
  Accuracy of VTE detection significantly improved with addition of treatment data to ICD-9 codes. This approach should facilitate use of administrative data to assess the incidence, epidemiology, and outcomes of VTE.
authors.affiliation: Saint Louis Veterans Health Administration Medical Center Research Service, College for Public Health and Social Justice, Saint Louis University, United States; Division of Hematology, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8125, St. Louis, MO 63110, United States. Electronic address: ksanfili@dom.wustl.edu.
authors.forename: Kristen M
authors.initials: KM
authors.lastname: Sanfilippo
authors.affiliation: Division of Hematology, The Ohio State University, 320 10th W. Ave, A340, Columbus OH 43210, United States. Electronic address: Tzu-Fei.Wang@osumc.edu.
authors.forename: Tzu-Fei
authors.initials: TF
authors.lastname: Wang
authors.affiliation: Division of General Medical Sciences, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8005, St. Louis, MO 63110, United States. Electronic address: bgage@im.wustl.edu.
authors.forename: Brian F
authors.initials: BF
authors.lastname: Gage
authors.affiliation: Saint Louis Veterans Health Administration Medical Center Research Service, College for Public Health and Social Justice, Saint Louis University, United States; Department of Biostatistics, Saint Louis University College for Public Health and Social Justice, Salus Center, 3545 Lafayette Ave., Cubicle 340, St. Louis, MO 63104, United States. Electronic address: wliu9@slu.edu.
authors.forename: Weijian
authors.initials: W
authors.lastname: Liu
authors.affiliation: Saint Louis Veterans Health Administration Medical Center Research Service, College for Public Health and Social Justice, Saint Louis University, United States; Division of Oncology, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8056, St. Louis, MO 63110, United States. Electronic address: kcarson@dom.wustl.edu.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Carson
mesh_terms: D000368:Aged; D005260:Female; D006296:Health Services; D006801:Humans; D038801:International Classification of Diseases / Q000592:standards*; D008297:Male; D054556:Venous Thromboembolism / Q000145:classification* / Q000453:epidemiology
keywords: Administrative data; Health service research; Venous thromboembolism