Prevention of venous thromboembolism in critically ill medical patients: a Franco-Canadian cross-sectional study.

Background: Medical intensive care unit (ICU) patients are at moderate risk of venous thromboembolism (VTE) and prophylaxis against VTE is recommended.

Objectives: To observe the range and frequency of VTE prophylaxis administered to medical ICU patients and to determine factors associated with different strategies in French and Canadian ICUs.

Design: Prospective cross-sectional observational study.

Results: 113/251 (45.0%) French and 29/30 (96.6%) Canadian ICUs agreed to participate. Of 1,222 critically ill medical patients, most were mechanically ventilated (62.5%). Overall, heparin VTE prophylaxis was administered to 63.9% patients, similarly between the 2 countries. Excluding patients with contraindications to heparin and those receiving therapeutic anticoagulation, 91.7% of medical ICU patients appropriately received either low dose unfractionated heparin (UFH) or low molecular weight heparin (LMWH) prophylaxis. Independent predictors of heparin prophylaxis were invasive mechanical ventilation (odds ratio [OR]; 95%CI, 2.4 (1.4-4.3) and obesity (OR 3.1; 1.1-8.8). LMWH was less likely to be prescribed for patients with renal failure (OR 0.1; 0.0009-0.9), or receiving antiembolic stockings (OR 0.4, 0.1-0.9), and much more likely to be prescribed in French ICUs (OR 9.2; 5.0-16.9); however, among patients receiving LMWH, high doses were more likely to be prescribed in Canadian ICUs (OR 8.7; 2.0-37.6). Patients who were pregnant or postpartum (OR 7.7, 1.3-44.3), had neurologic failure (OR 2.1, 1.3-3.4), or were Canadian (OR 3.0, 2.1-4.4) were most likely to receive mechanical VTE prophylaxis (with antiembolic stockings or pneumatic compression devices), whereas those who were already receiving heparin were less likely to receive mechanical prophylaxis (OR 0.5, 0.3-0.7).

Conclusions: In this binational cross-sectional observational study of medical ICU patients, we found that 92% of eligible patients received either UFH or LWMH for VTE prophylaxis. Differences in prescribing between countries include significantly greater use of LMWH in France, but use of lower doses than in Canada, and greater use of mechanical VTE prophylaxis in Canada. More randomized trials of VTE prophylaxis in critically ill medical patients would better inform practice.