title: ICD-9-CM codes poorly indentified venous thromboembolism during pregnancy.
abstract: OBJECTIVE
  There is little data regarding the accuracy of pregnancy-specific ICD-9-CM codes used to identify patients with venous thromboembolism (VTE).
  
  
  METHODS
  We identified a large cohort of pregnant patients in whom there were one or more pregnancy-specific (600 codes) or standard ICD-9-CM codes (400 codes) for VTE. Charts of these cases were abstracted to determine the presence of objectively documented VTE.
  
  
  RESULTS
  A total of 214 cases had a code for VTE either during pregnancy or the 6-week postpartum period; 82% had a pregnancy-specific code and 18% a standard code. Overall, 84 (39%, 95% CI=33-46%) had objectively documented VTE. A pregnancy-specific ICD-9-CM for VTE had a positive predictive value (PPV) of 54/174=31% (95% CI=24-38%), whereas standard VTE codes had a PPV of 30 of 38=80% (95% CI=63-99%). A PPV in the range of 95-100% could be attained using other criteria, at the expense of detecting only 28 to 45% of all VTE cases.
  
  
  CONCLUSIONS
  Pregnancy-specific ICD-9-CM codes for VTE have low PPV. Other criteria must be applied to select cases with a high probability of having objectively documented VTE.
authors.affiliation: Division of General Medicine, University of California-Davis, Suite 2400, 4150 V Street, Sacramento, CA 95817, USA. rhwhite@ucdavis.edu
authors.forename: Richard H
authors.initials: RH
authors.lastname: White
authors.forename: Leslea A
authors.initials: LA
authors.lastname: Brickner
authors.forename: Kate A
authors.initials: KA
authors.lastname: Scannell
mesh_terms: D000328:Adult; D002140:California / Q000453:epidemiology; D005260:Female; D006801:Humans; D038801:International Classification of Diseases; D008499:Medical Records / Q000592:standards; D011237:Predictive Value of Tests; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology*; D011655:Pulmonary Embolism / Q000453:epidemiology*; D020246:Venous Thrombosis / Q000453:epidemiology*