title: Using multiple sources of data for surveillance of postoperative venous thromboembolism among surgical patients treated in Department of Veterans Affairs hospitals, 2005-2010.
abstract: BACKGROUND
  There are limitations to using administrative data to identify postoperative venous thromboembolism (VTE). We used a novel approach to quantify postoperative VTE events among Department of Veterans Affairs (VA) surgical patients during 2005-2010.
  
  
  METHODS
  We used VA administrative data to exclude patients with VTE during 12 months prior to surgery. We identified probable postoperative VTE events within 30 and 90 days post-surgery in three settings: 1) pre-discharge inpatient, using a VTE diagnosis code and a pharmacy record for anticoagulation; 2) post-discharge inpatient, using a VTE diagnosis code followed by a pharmacy record for anticoagulation within 7 days; and 3) outpatient, using a VTE diagnosis code and either anticoagulation or a therapeutic procedure code with natural language processing (NLP) to confirm acute VTE in clinical notes.
  
  
  RESULTS
  Among 468,515 surgeries without prior VTE, probable VTEs were documented within 30 and 90 days in 3,931 (0.8%) and 5,904 (1.3%), respectively. Of probable VTEs within 30 or 90 days post-surgery, 47.8% and 62.9%, respectively, were diagnosed post-discharge. Among post-discharge VTE diagnoses, 86% resulted in a VA hospital readmission. Fewer than 25% of outpatient records with both VTE diagnoses and anticoagulation prescriptions were confirmed by NLP as acute VTE events.
  
  
  CONCLUSIONS
  More than half of postoperative VTE events were diagnosed post-discharge; analyses of surgical discharge records are inadequate to identify postoperative VTE. The NLP results demonstrate that the combination of VTE diagnoses and anticoagulation prescriptions in outpatient administrative records cannot be used to validly identify postoperative VTE events.
authors: Veterans Affairs Salt Lake City Health Care System, USA; University of Utah Department of Internal Medicine, Salt Lake City, UT, USA. Electronic address: richard.nelson@utah.edu.
authors: Richard E
authors: RE
authors: Nelson
authors: National Center on Birth Defects and Developmental Disabilities, Office of the Director, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors: Scott D
authors: SD
authors: Grosse
authors: University of Utah Department of Economics, Salt Lake City, UT, USA.
authors: Norman J
authors: NJ
authors: Waitzman
authors: Veterans Affairs Salt Lake City Health Care System, USA; University of Utah Department of Pharmacotherapy, Salt Lake City, UT, USA.
authors: Junji
authors: J
authors: Lin
authors: Veterans Affairs Salt Lake City Health Care System, USA; University of Utah Department of Internal Medicine, Salt Lake City, UT, USA; University of Utah Department of Pharmacotherapy, Salt Lake City, UT, USA.
authors: Scott L
authors: SL
authors: DuVall
authors: Veterans Affairs Salt Lake City Health Care System, USA; University of Utah Department of Internal Medicine, Salt Lake City, UT, USA.
authors: Olga
authors: O
authors: Patterson
authors: Office on Smoking and Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors: James
authors: J
authors: Tsai
authors: National Center on Birth Defects and Developmental Disabilities, Division of Blood Disorders, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors: Nimia
authors: N
authors: Reyes
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D049674:History, 21st Century; D006761:Hospitals; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D062486:Public Health Surveillance; D012189:Retrospective Studies; D013223:Statistics as Topic / Q000379:methods*; D014481:United States; D054556:Venous Thromboembolism / Q000453:epidemiology; D014728:Veterans
keywords: Deep vein thrombosis; Pulmonary embolism; Surgery; Venous thromboembolism; Veterans