Research Article
No access
Published Online: 17 March 2006

Risk of Impaired Coagulation in Warfarin Patients Ascending to Altitude (>2400 m)

Publication: High Altitude Medicine & Biology
Volume 7, Issue Number 1

Abstract

Tissot van Patot, Martha C., Ashley E. Hill, Colleen Dingmann, Lawrence Gaul, Kelly Fralick, Uwe Christians, Benjamin Honigman, and M.D. Salman. Risk of impaired coagulation in warfarin patients ascending to altitude (>2400 m). High Alt. Med. & Biol. 7:39–46, 2006.—Approximately 476,000 people on warfarin therapy visit a resort at altitude (>2400 m) annually in Colorado. Clinicians practicing at altitude have expressed concern that ascent to altitude adversely affects coagulation in patients taking warfarin in both high altitude residents and visitors. We sought to determine the effect of ascent to and descent from altitude on coagulation in warfarin patients, as assessed by the international normalized ratio (INR). A retrospective medical chart review was conducted on all warfarin patients treated between August 1998 and October 2003 at a cardiology clinic in which travel to and from altitude was documented in association with each INR measurement in high altitude residents. Of the 1139 INR measurements in 49 patients, 143 were associated with changes in altitude (in 32 of 49 patients). The odds of an INR measurement being below the prescribed range were 2.7 times (95% CI: 1.2–5.8) higher among warfarin patients with recent ascent to altitude, 2.1 times (95% CI: 1.4–3.2) higher among warfarin patients with atrial fibrillation, and 5.6 (95% CI: 2.3–13.7) times higher among warfarin patients with both atrial fibrillation and recent ascent to altitude. Increasing altitude is a risk factor for subtherapeutic INR in warfarin patients and this risk is doubled in atrial fibrillation patients.

Get full access to this article

View all available purchase options and get full access to this article.

Information & Authors

Information

Published In

cover image High Altitude Medicine & Biology
High Altitude Medicine & Biology
Volume 7Issue Number 1Spring 2006
Pages: 39 - 46
PubMed: 16544965

History

Published online: 17 March 2006
Published in print: Spring 2006

Permissions

Request permissions for this article.

Topics

    Authors

    Affiliations

    Martha C. Tissot Van Patot, PhD.
    Department of Anesthesiology, University of Colorado Denver Health Sciences Center, Denver, Colorado.
    Colorado Center for Altitude Medicine and Physiology, University of Colorado Denver Health Sciences Center, Denver, Colorado.
    Ashley E. Hill
    Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado.
    Colleen Dingmann
    Department of Anesthesiology, University of Colorado Denver Health Sciences Center, Denver, Colorado.
    Colorado Center for Altitude Medicine and Physiology, University of Colorado Denver Health Sciences Center, Denver, Colorado.
    Lawrence Gaul
    Aurora Denver Cardiology Associates, Vail, Colorado.
    Kelly Fralick
    Aurora Denver Cardiology Associates, Vail, Colorado.
    Uwe Christians
    Department of Anesthesiology, University of Colorado Denver Health Sciences Center, Denver, Colorado.
    Colorado Center for Altitude Medicine and Physiology, University of Colorado Denver Health Sciences Center, Denver, Colorado.
    Benjamin Honigman
    Colorado Center for Altitude Medicine and Physiology, University of Colorado Denver Health Sciences Center, Denver, Colorado.
    Division of Emergency Medicine, Department of Surgery, University of Colorado Denver Health Sciences Center, Denver, Colorado.
    M.D. Salman
    Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado.

    Metrics & Citations

    Metrics

    Citations

    Export citation

    Select the format you want to export the citations of this publication.

    View Options

    Get Access

    Access content

    To read the fulltext, please use one of the options below to sign in or purchase access.

    Society Access

    If you are a member of a society that has access to this content please log in via your society website and then return to this publication.

    Restore your content access

    Enter your email address to restore your content access:

    Note: This functionality works only for purchases done as a guest. If you already have an account, log in to access the content to which you are entitled.

    View options

    PDF/EPUB

    View PDF/ePub

    Media

    Figures

    Other

    Tables

    Share

    Share

    Copy the content Link

    Share on social media

    Back to Top