Venous thromboembolism in critically ill patients: incidence and risk factors

Objective

Despite the high risk of venous thromboembolism (VTE) in ICU patients, only few studies have examined this group of patients systematically. The objective of this study is to examine the incidence and risk factors of VTE among critically ill patients.

Design

A prospective cohort study.

Setting

A closed university-affiliated ICU in a medical–surgical ICU in the Kingdom of Saudi Arabia.

Patients

We enrolled consecutive patients >12 years of age expected to stay in the ICU >48 hours. We excluded patients on systemic anticoagulation and patients with pulmonary embolism (PE) or deep venous thrombosis (DVT) on admission to the ICU or diagnosed within 24 hours of ICU admission. We recorded a priori defined VTE risk factors at baseline and daily. Our ICU implements a protocol for thromboprophylaxis, which is based on the evidence-based ACCP guidelines. The primary endpoint was the development of PE or DVT during ICU stay. We used multivariate regression analysis to determine independent predictors of VTE.

Results

Among 277 patients with a mean APACHE II score of 25 (+9), the incidence of VTE was 7.2% (95% CI 4.5–11). We identified three independent risk factors for ICU-acquired venous thromboembolism: stroke (OR 13.5, 95% CI 1.9–91.19, P = 0.008), femur fracture (OR 4.5, 95% CI 1.18–17.10, P = 0.03), and ICU length of stay (OR for each day increment 1.08, 95% CI 1.03–1.13, P = 0.002). After adjustment for APACHE II score, VTE was an independent predictor of mortality (OR 3.85, 95% CI 1.11–13.29, P = 0.03).

Conclusion

VTE is relatively common complication in critically ill patients and is associated with significant mortality. Longer ICU length of stay, stroke and femur fracture are independent predictors for VTE. These findings suggest the need for more effective prophylactic strategies in critically ill patients, especially those at higher risk.