Safety and efficacy of low dose fondaparinux (1.5 mg) for the prevention of venous thromboembolism in acutely ill medical patients with renal impairment. The FONDAIR study.

Background: Renal impairment is common affecting around 40% of acutely ill medical patients and is associated with an increased risk of both venous thromboembolism (VTE) and bleeding. The clinical benefit of effective thromboprophylactic strategies may be outweighed in these patients by an excessive rate of hemorrhage. Objective: To assess the safety and efficacy of lower prophylactic doses of fondaparinux in acutely ill medical patients with renal impairment. Patients/Methods: We carried out a multicenter, investigator-initiated, prospective cohort study. Patients at risk for VTE with a creatinine clearance between 20 and 50 mL/min were treated with fondaparinux 1.5 mg qd for a minimum of 6 to a maximum of 15 days. Primary outcome was the incidence of major bleeding, secondary outcomes were clinically relevant non-major bleeding (CRNMB) and symptomatic VTE. Results: We enrolled 206 patients with a mean age of 82 years, mean creatinine clearance of 33 mL/min, and a mean Charlson co-morbidity index of 8.2. One patient had major bleeding (0.49%, 95% CI 0.03-3.10), 8 had CRNMB (3.88%, 95% CI 1.81-7.78), and 3 developed symptomatic VTE (1.46%, 0.38-4.55). Twenty-three patients (11.17%, 7.36-16.48) died. No independent predictors of bleeding were found at univariate analysis. Conclusions: The addition of moderate to severe renal impairment to patients with traditional risk factors for VTE identified a population of very elderly acutely ill medical patients potentially at high risk for both VTE and bleeding complications. The recently approved lower prophylactic dose of fondaparinux appears to be a safe and relatively effective strategy in these patients.