title: Risk factor model to predict venous thromboembolism in hospitalized medical patients.
abstract: BACKGROUND
  The Joint Commission requires that all medical inpatients be assessed for venous thromboembolism (VTE) risk, but available risk stratification tools have never been validated.
  
  
  METHODS
  We conducted a retrospective cohort study of patients age ≥18 years, admitted to 374 US hospitals in 2004-2005, with a primary diagnosis of pneumonia, heart failure, chronic obstructive pulmonary disease (COPD), stroke, and urinary tract infection, and length of stay ≥3 days. Subjects were randomly assigned (80/20) to a derivation or validation set. We then assessed VTE (International Classification of Diseases, Ninth Revision [ICD-9] code plus diagnostic test plus treatment), patient demographics, 21 potential risk factors, and other comorbidities. We created a VTE risk stratification tool using multivariable regression modeling and applied it to the validation sample.
  
  
  RESULTS
  Of 242,738 patients, 612 (0.25%) patients fulfilled our criteria for VTE during hospitalization, and an additional 440 (0.18%) were readmitted for VTE within 30 days (overall incidence of 0.43%). In the multivariable model, age, sex, and 10 additional risk factors were associated with VTE. The strongest risk factors were inherited thrombophilia (OR 4.00), length of stay ≥6 days (OR 3.22), inflammatory bowel disease (OR 3.11), central venous catheter (OR 1.87), and cancer. In the validation set, the model had a c-statistic of 0.75 (95% CI 0.71, 0.78). Deciles of predicted risk ranged from 0.11% to 1.46% with observed risk over the same deciles from 0.17% to 1.81%.
  
  
  CONCLUSIONS
  The risk of symptomatic VTE in general medical patients is low. A risk factor model can identify those at sufficient risk to warrant pharmacologic prophylaxis.
authors.affiliation: Center for Quality of Care Research, Baystate Medical Center, Springfield, Massachusetts, USA. Michael.Rothberg@bhs.org
authors.forename: Michael B
authors.initials: MB
authors.lastname: Rothberg
authors.forename: Peter K
authors.initials: PK
authors.lastname: Lindenauer
authors.forename: Maureen
authors.initials: M
authors.lastname: Lahti
authors.forename: Penelope S
authors.initials: PS
authors.lastname: Pekow
authors.forename: Harry P
authors.initials: HP
authors.lastname: Selker
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006748:Hospital Departments / Q000639:trends*; D006760:Hospitalization / Q000639:trends*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D054556:Venous Thromboembolism / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D055815:Young Adult