Risk of Thromboembolism Varies, Depending on Category of Immobility in Outpatients
Received 14 July 2008; received in revised form 1 October 2008 and 15 October 2008; accepted 31 October 2008. published online 09 January 2009.
Refers to article:
Moving Beyond Immobilization
, 23 February 2009
David L. Schriger
Annals of Emergency Medicine
August 2009 (Vol. 54, Issue 2, Pages 153-154) Full Text |
Full-Text PDF (91 KB)
Study objective
Immobility predisposes to venous thromboembolism, but this risk may vary, depending on the underlying cause of immobility.
Methods
This was a prospective, longitudinal outcome study of self-presenting emergency department (ED) patients who were from 12 hospitals and had suspected venous thromboembolism. Using explicit written criteria, clinicians recorded clinical features of each patient in the ED by using a Web-based data form. The form required one of 6 types of immobility: no immobility, general or whole-body immobility greater than 48 hours, limb (orthopedic) immobility, travel greater than 8 hours causing immobility within the previous 7 days, neurologic paralysis, or other immobility not listed above. Patients were followed for 45 days for outcome of venous thromboembolism, which required positive imaging results and clinical plan to treat. Odds ratios (ORs) were derived from logistic regression including 12 covariates.
Results
From 7,940 patients enrolled, 545 of 7,940 (6.9%) were diagnosed with venous thromboembolism (354 pulmonary embolism, 72 deep venous thrombosis, 119 pulmonary embolism and deep venous thrombosis). Risk of venous thromboembolism varied, depending on immobility type: limb (OR=2.24; 95% confidence interval [CI] 1.40 to 3.60), general (OR=1.76; 95% CI 1.26 to 2.44), other (OR=1.97; 95% CI 1.25 to 3.09), neurologic (OR=2.23; 95% CI 1.01 to 4.92), and travel (OR=1.19; 95% CI 0.85 to 1.67). Other significant risk factors from multivariate analysis included age greater than 50 years (OR =1.5; 95% CI 1.25 to 1.82), unilateral leg swelling (OR=2.68; 95% CI 2.13 to 3.37), previous venous thromboembolism (OR=2.99; 95% CI 2.41 to 3.71), active malignancy (OR=2.23; 95% CI 1.69 to 2.95), and recent surgery (OR=2.12; 95% CI 1.61 to 2.81).
Conclusion
In a large cohort of symptomatic ED patients, risk of venous thromboembolism was substantially increased by presence of limb, whole-body, or neurologic immobility but not by travel greater than 8 hours. These data show the importance of clarifying the cause of immobility in risk assessment of venous thromboembolism.
aBrody School of Medicine at East Carolina University, Greenville, NC
Address for reprints: Jeffrey A. Kline, MD, Emergency Medicine Research, Department of Emergency Medicine, Carolinas Medical Center, PO Box 32861, Charlotte, NC 28323-2861; 704-355-7092, fax 704-355-7047
Author contributions: DMB collected and analyzed data and wrote the first draft of the article. DMC performed the statistical and graphic analyses and edited the article. CK, CLM, and PBR helped develop this idea, participated in study definitions, performed data entry, and assisted with article production. CK, CLM, PBR, and JAK enrolled patients and performed database queries. JAK conceived the work, obtained funding, contributed to the primary analyses, and edited the article. JAK takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. Supported by a Resident Research Award from the Emergency Medicine Foundation.
Publication date: Available online January 7, 2009.
ABSTRACT