title: Retrospective administrative database study of the time period of venous thromboembolism risk during and following hospitalization for major orthopedic or abdominal surgery in real-world US patients.
abstract: OBJECTIVE
  To assess the incidence and time course of symptomatic venous thromboembolism (VTE) events in patients during and following hospitalization for major orthopedic or abdominal surgery.
  
  
  METHODS
  Data were extracted from the Thomson Reuters MarketScan(®) Inpatient Drug Link File for surgical patients admitted between January 2005 and December 2008. The analysis included 8989 abdominal surgery patients and 4220 orthopedic surgery patients. The cumulative risks of VTE and VTE hazard were assessed over a 180-day evaluation period after the hospital admission date, using Kaplan-Meier analysis and LOESS regression, respectively.
  
  
  RESULTS
  In total, 305 (2.3%) patients experienced a symptomatic VTE event. These were most frequent during days 1-9 (78 events) and 10-19 (72 events). In all, 64% of events occurred after discharge. Venous thromboembolism hazard peaked at approximately 1.3 per 1000 person-days (day 8) following orthopedic surgery and at approximately 0.52 per 1000 person-days (day 11) following abdominal surgery. In-hospital pharmacologic prophylaxis was received by 88.3% and 30.2% of orthopedic and abdominal surgery patients, respectively, whereas pharmacologic prophylaxis following hospitalization was received by 41.3% and 3.0% of patients, respectively.
  
  
  CONCLUSIONS
  The time course of VTE in major surgery patients suggests that VTE risk is highest during the first 19 days after admission and that considerable VTE risk extends into the period after discharge.
authors.affiliation: School of Medicine, University of California-Irvine, Orange, CA 92868, USA. anamin@uci.edu
authors.forename: Alpesh N
authors.initials: AN
authors.lastname: Amin
authors.forename: Greg
authors.initials: G
authors.lastname: Lenhart
authors.forename: Nicole
authors.initials: N
authors.lastname: Princic
authors.forename: Jay
authors.initials: J
authors.lastname: Lin
authors.forename: Stephen
authors.initials: S
authors.lastname: Thompson
authors.forename: Stephen
authors.initials: S
authors.lastname: Johnston
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D016208:Databases, Factual; D005260:Female; D013502:General Surgery; D013509:Gynecologic Surgical Procedures / Q000009:adverse effects; D006801:Humans; D008297:Male; D008498:Medical Record Linkage; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000009:adverse effects; D011183:Postoperative Complications / Q000453:epidemiology* / Q000517:prevention & control; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D013514:Surgical Procedures, Operative / Q000009:adverse effects*; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D054556:Venous Thromboembolism / Q000453:epidemiology* / Q000209:etiology* / Q000517:prevention & control; D055815:Young Adult
chemical_list: D000925:Anticoagulants