title: High altitude is an independent risk factor for venous thromboembolism following arthroscopic rotator cuff repair: a matched case-control study in Medicare patients.
abstract: BACKGROUND
  Although the risk of venous thromboembolism (VTE) following elective shoulder arthroscopy is low, the large volume of procedures performed each year yields a significant annual burden of patients with thromboembolic complications. The purpose of this study was to evaluate the association of high procedural altitude with the incidence of postoperative VTE following arthroscopic rotator cuff repair.
  
  
  METHODS
  A Medicare database was queried for all patients undergoing arthroscopic rotator cuff repair from 2005 to 2012. All patients with procedures performed at an altitude of 4000 feet or higher were grouped into the "high-altitude" study cohort. Patients with procedures performed at an altitude of 100 feet or lower were then matched to patients in the high-altitude cohort on the basis of age, gender, and medical comorbidities. The rate of VTE was then assessed for both the high-altitude and matched low-altitude cohorts within 90 days postoperatively.
  
  
  RESULTS
  The rates of combined VTE (odds ratio [OR], 2.6; P < .0001), pulmonary embolism (OR, 4.3; P < .0001), and lower extremity deep venous thrombosis within 90 days (OR, 2.2; P = .029) were all significantly higher in patients with procedures performed at high altitude compared with matched patients with the same procedures performed at low altitude.
  
  
  CONCLUSIONS
  Procedural altitude >4000 feet is associated with significantly increased rates of postoperative VTE, including deep venous thrombosis and pulmonary embolism, compared with age-, gender-, and comorbidity-matched patients undergoing the same procedures at altitudes <100 feet.
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: Jourdan M
authors.initials: JM
authors.lastname: Cancienne
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: M Tyrrell
authors.initials: MT
authors.lastname: Burrus
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Diduch
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA. Electronic address: bcw4x@virginia.edu.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Werner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000531:Altitude; D001182:Arthroscopy / Q000009:adverse effects*; D016022:Case-Control Studies; D017558:Elective Surgical Procedures / Q000009:adverse effects; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D006278:Medicare; D008875:Middle Aged; D016017:Odds Ratio; D011183:Postoperative Complications / Q000453:epidemiology*; D011655:Pulmonary Embolism / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D000070636:Rotator Cuff Injuries / Q000150:complications / Q000601:surgery*; D014481:United States / Q000453:epidemiology; D054556:Venous Thromboembolism / Q000453:epidemiology*; D020246:Venous Thrombosis / Q000453:epidemiology*
keywords: DVT; PE; Rotator cuff repair; VTE; complications; high altitude