The Effects of the Degree of Mobility Reduction and Prespecified Risk Factors on Venous Thromboembolism Rates in Acutely Ill Medical Patients in the EXCLAIM Study.

Introduction EXCLAIM showed a 44% reduction of the relative risk of venous thromboembolism (VTE) with extended-duration enoxaparin prophylaxis compared with placebo, following standard-duration prophylaxis in acutely ill medical patients (2.8% vs 4.9%; RR 0.56; 95% CI 0.39–0.80; p=0.001). We retrospectively assessed the effects of degree of reduced mobility and prespecified risk factors on the incidence of VTE in EXCLAIM.

Methods EXCLAIM eligibility required a recent (≤3 days) reduction in mobility due to acute medical illness, an anticipated level 1 (total bed rest/sedentary; no bathroom privileges) or level 2 (level 1 with bathroom privileges) decreased mobility, and age ≥40 years. During the latter part of the study, a protocol amendment required patients with level 2 mobility to have ≥1 of 3 additional prespecified risk factors (history of cancer, history of VTE, age >75 years). Enrolled patients received enoxaparin 40mg SC od for 10±4 days. Randomized patients received double-blind therapy (enoxaparin 40mg SC od or placebo) for 28±4 additional days. Patients were screened for deep vein thrombosis with bilateral proximal lower extremity compression ultrasound after randomized therapy. A blinded committee adjudicated cases of suspected VTE and major bleeding.

Results Of patients evaluable for VTE (pre- and post-amendment; n=4995), 42% had level 1 mobility. 43% with level 2 mobility met the amended eligibility criteria. The incidence of VTE was 3.2%. Treatment effects on VTE incidence and major bleeding rates were consistent within mobility groups, regardless of the presence of prespecified risk factors (Table). In patients with level 1 mobility, those with ≥1 prespecified risk factors had a higher VTE incidence than those without (4.8% vs 2.6%; p=0.007). In patients with level 2 mobility, those with ≥1 risk factors had a higher VTE incidence than those without (4.6% vs 1.9%; p<0.0001).

Conclusion After acutely ill medical patients with reduced mobility received standard-duration VTE prophylaxis, the presence of prespecified risk factors was associated with an increased incidence of VTE, independent of the level of reduced mobility. The treatment effects of extended-duration prophylaxis with enoxaparin compared with placebo were consistent among subgroups.