title: Thrombosis as a complication of extended stay at high altitude.
abstract: BACKGROUND
  There is limited knowledge about the medical problems of long term stay at high (> 3000 m) and extreme (> 5000 m) altitudes, as these areas are generally considered uninhabitable.
  
  
  METHODS
  Prospectively collected clinical records of all patients hospitalized at Command Hospital, Western Command between November 1998 and February 2000 were reviewed to identify thrombotic complications among patients from high and extreme altitude areas as well as those from non-high altitude areas who were < 45 years of age.
  
  
  RESULTS
  Of 20,257 hospital admissions during the study period, 1692 were from high and extreme altitude areas. Forty-six patients from these areas had thrombosis-related diseases compared to 17 from non-high altitude areas (odds ratio: 30.49; 95% CI: 17.06-51.67; p < 0.001). The mean (SD) age of all patients with thrombotic complications was 32 (8) years and all were men. The mean duration of stay at high and extreme altitudes of such patients was 10.2 (5.6) months. Only 25 were smokers (mean 5.2 pack-years) and 39 consumed alcohol (mean 54 ml/day). Apart from frostbite in 5, no other medical condition was noted in these patients. The vascular events were deep vein thrombosis (20), pulmonary thromboembolism (6), stroke (15), thrombosis of the abdominal veins (8), and retinal artery and peripheral arterial thrombosis (1 each). The presenting complaint in all patients with thrombosis of the abdominal veins was poorly localized pain in the upper abdomen followed by ascites (6/8). Five of these patients also had a large spontaneous splenic haematoma. None of the patients investigated was found to have a procoagulant disorder.
  
  
  CONCLUSIONS
  Long term stay at high and extreme altitudes is associated with a 30 times higher risk of spontaneous vascular thrombosis. Veins are common sites of such thrombotic events. We also encountered thrombosis of the portal, splenic and superior mesenteric veins in our patients who had stayed at high and extreme altitudes.
authors.affiliation: Department of Gastroenterology, Command Hospital, Western Command, Chandimandir 134107, Haryana, India.
authors.forename: A C
authors.initials: AC
authors.lastname: Anand
authors.forename: S K
authors.initials: SK
authors.lastname: Jha
authors.forename: A
authors.initials: A
authors.lastname: Saha
authors.forename: V
authors.initials: V
authors.lastname: Sharma
authors.forename: C M
authors.initials: CM
authors.lastname: Adya
mesh_terms: D000328:Adult; D000531:Altitude; D006772:Hospitals, Military; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data; D010343:Patient Admission / Q000706:statistics & numerical data; D011159:Population Surveillance; D011446:Prospective Studies; D012017:Referral and Consultation / Q000706:statistics & numerical data; D012307:Risk Factors; D013927:Thrombosis / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D018608:Ultrasonography, Doppler