title: The validity of ICD-9-CM codes in identifying postoperative deep vein thrombosis and pulmonary embolism.
abstract: BACKGROUND
  Deep vein thrombosis and pulmonary embolism (DVT/PE) are common complications after surgery and are associated with substantial excess mortality and length of stay. International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes recorded in hospital claims have been used to identify and study DVT/PE, but the validity of this method is not well studied.
  
  
  METHODS
  Identification of postoperative DVT/PE events were compared using ICD-9-CM codes and medical record abstraction in random samples of hospital discharges of Medicare beneficiaries in 2002-2004.
  
  
  RESULTS
  Among 20,868 eligible surgical hospitalizations, 232 DVT cases and 95 PE cases were identified by ICD-9-CM codes; 108 DVT cases and 31 PE cases by medical record abstraction; 72 DVT cases and 23 PE cases by both methods. The resulting estimates of PPV of ICD9-CM coding were 31% (72/232 cases) for DVT, 24% (23/95) for PE, and 29% (90/308) for DVT/PE combined. The resulting sensitivity estimates were 67% (72/108 cases) for DVT, 74% (23/31) for PE, and 68% (90/133) for DVT/PE combined.
  
  
  CONCLUSIONS
  ICD-9-CM codes in Medicare claims are sensitive but have limited predictive validity in identifying postoperative DVT/PE. Improvements in the validity are needed before the indicator can be used for safety performance assessment.
authors.affiliation: Agency for Healthcare Research and Quality, Department of Health and Human Services, Rockville, MD, USA. Chunliu.Zhan@ahrq.hhs.gov
authors.forename: Chunliu
authors.initials: C
authors.lastname: Zhan
authors.forename: James
authors.initials: J
authors.lastname: Battles
authors.forename: Yen-Pin
authors.initials: YP
authors.lastname: Chiang
authors.forename: David
authors.initials: D
authors.lastname: Hunt
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007345:Insurance Claim Review / Q000706:statistics & numerical data*; D038801:International Classification of Diseases; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data*; D006278:Medicare / Q000706:statistics & numerical data; D011183:Postoperative Complications / Q000175:diagnosis*; D011655:Pulmonary Embolism / Q000175:diagnosis*; D011785:Quality Assurance, Health Care / Q000379:methods; D015203:Reproducibility of Results; D020246:Venous Thrombosis / Q000175:diagnosis*