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Etiology

Lower limb and spinal cord injuries increased the risk for venous thromboembolism after major trauma

ACP J Club. 1995 May-June;122:78. doi:10.7326/ACPJC-1995-122-3-078


Source Citation

Geerts WH, Code KI, Jay RM, Chen E, Szalai JP. A prospective study of venous thromboembolism after major trauma. N Engl J Med. 1994 Dec 15;331:1601-6.


Abstract

Objective

To determine the frequency of deep venous thrombosis (DVT) in patients with trauma and the incidence of DVT in trauma subgroups and to identify patient characteristics associated with increased risk for thromboembolic complications.

Design

Cohort study with 2-year follow-up.

Setting

Trauma unit of a tertiary care center in Canada.

Patients

716 patients (mean age 37 y, 71% men) who were admitted to the trauma unit with an Injury Severity Score (ISS) of ≥ 9. Exclusion criteria were death or discharge ≤ 5 days after the injury, allergy to radiographic contrast agents, renal failure, foot injury precluding successful venography, and the need for anticoagulation. Among the eligible patients, venography was attempted in 443 and was adequate in 349. Prophylaxis against DVT was not used.

Assessment of risk factors

Age, sex, cause of injury, ISS, Abbreviated Injury Scale score for each of the 6 body regions, major sites of injury, specific injuries, blood group, transfusion requirements, need for surgery, cumulative time in operating room, mobility, and duration of hospital stay. A panel of experts evaluated test results unaware of the clinical details and the original interpretation of the test.

Main outcome measure

Occurrence of DVT.

Main results

Of 349 patients, 201 (57.6%) had DVT and 63 (18.1%) had proximal DVT. DVT occurred in 50% of patients with major face, chest, or abdominal injuries; 54% of patients with major head injuries; 62% of patients with spinal injuries; and 69% of patients with fractures of the lower extremities. DVT was associated with spinal cord injury (odds ratio [OR] 8.59, 95% CI 2.92 to 25.3), fracture of the femur or the tibia (OR 4.82, CI 2.79 to 8.33), surgery (OR 2.3 CI 1.08 to 4.89), blood transfusion ≤ 24 hours after admission (OR 1.74, CI 1.03 to 2.93), and older age (OR 1.05 for each 1-y increment, 95% CI 1.03 to 1.06). Patients with DVT had less mobility than patients without DVT (mean maximal mobility score at the third week 2.6 vs 3.4, P < 0.001) and a longer mean hospital stay (36.7 vs 28.1 d).

Conclusions

Deep venous thrombosis occurred in 58% of a single cohort of patients with major trauma who had not received prophylaxis for deep venous thrombosis. Patients at highest risk were those with injuries to the lower extremities and the spinal cord.

Sources of funding: Ontario Ministry of Health; Rick Hansen Man in Motion Legacy Fund/Canadian Paraplegic Association; Sunnybrook Trust for Research.

For article reprint: Dr. W.H. Geerts, Sunnybrook Health Science Centre, Room D674, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada. FAX 416-480-4186.


Revised Commentary

This study by Geerts and colleagues shows the high incidence of DVT after major trauma. They avoided selection and work-up biases by enrolling consecutive patients and applying the gold standard of DVT diagnosis, contrast venography, as widely as possible. Of 1008 admissions to the trauma unit during the study period, 716 were eligible and 349 had useful venographic results. Although the 349 study patients had more severe and DVT-prone injuries than the initial cohort of 716 patients, these differences were slight and unlikely to have distorted the results.

This study confirms that DVT is common after major trauma. In a subsequent study published in 1996 after the initial ACP Journal Club commentary, the same investigators randomized consecutive trauma patients (injury severity score ≥ 9, no head injury) to either low-dose unfractionated heparin (LDH), 5000 units, or enoxaparin, 30 mg, by twice daily subcutaneous injection (1). Enoxaparin was associated with a lower rate of proximal DVT than was LDH (6% vs 15%, P = 0.012). Of 344 patients, only 6 (1 in the LDH group and 5 in the enoxaparin group) had major bleeding.

These 2 studies make a strong case for prophylaxis with enoxaparin in patients with multiple trauma, particularly if lower extremity and spinal cord injuries are present. The bleeding risk seems acceptable, with the exception of patients with intracranial bleeding. DVT screening strategies that rely on clinical findings and objective tests are either unreliable (e.g., ultrasonography) or impractical (e.g., venography) (2).

Daniel M Becker, MD
University of Virginia School of MedicineCharlottesville, Virginia, USA


References

1. Geerts WH, Jay RM, Code KI, et al. A comparison of low-dose heparin with low-molecular-weight heparin as prophylaxis against venous thromboembolism after major trauma. N Engl J Med. 1996;335:701-7.

2. Clagett CP, Anderson FA Jr, Levine MN, Salzman EW, Wheeler HB. Prevention of venous thromboembolism. Chest. 1992;102 (4 Suppl):391S-407S.