Lack of effect of a low-molecular-weight heparin (nadroparin) on mortality in bedridden medical in-patients: a prospective randomised double-blind study

Anticoagulant prophylaxis to prevent asymptomatic deep vein thrombosis in hospitalized medical patients: a systematic review and meta-analysis

BACKGROUND

The effect of anticoagulant prophylaxis on the prevention of deep vein thrombosis (DVT) should include an investigation of both clinical and subclinical DVT. We conducted a systematic review to determine whether anticoagulant prophylaxis reduces the risk of asymptomatic DVT compared to no prophylaxis in at-risk hospitalized medical patients.

METHODS

MEDLINE, EMBASE, and the Cochrane Library were searched through March 2007 for randomized trials of anticoagulant prophylaxis for the prevention of asymptomatic DVT, assessed by venogram or ultrasound. We assessed four outcomes: all asymptomatic DVT, asymptomatic proximal DVT, major bleeding and mortality. Random effects meta-analyses were performed and results were expressed using relative risk (RR) and 95% confidence intervals (95% CIs).

RESULTS

Four trials including 5516 patients were eligible. Our pooled analysis demonstrated that compared to placebo, anticoagulant prophylaxis was associated with a significantly lower risk of any asymptomatic DVT (RR 0.51; 95% CI 0.39-0.67) and asymptomatic proximal DVT (RR 0.45; 95% CI 0.31-0.65). Anticoagulant prophylaxis was associated with a significantly increased risk of major bleeding compared to placebo (RR 2.00; 95% CI 1.05-3.79). There was no significant difference in the pooled estimate for all-cause mortality. Anticoagulant prophylaxis conferred an absolute risk reduction of any DVT and proximal DVT of 2.6% and 1.8%, respectively, and was associated with a 0.5% absolute risk increase in major bleeding.

CONCLUSIONS

Anticoagulant prophylaxis is effective in preventing asymptomatic DVT in at-risk hospitalized medical patients but is associated with an increased bleeding risk. The therapeutic benefits of anticoagulant prophylaxis appear to outweigh the risks of bleeding.

Primary prevention of venous thromboembolism in elderly medical patients

Primary prophylaxis with the use of an effective and safe intervention appears the best approach of venous thromboembolism (VTE) management in medical elderly patients, the most affected by VTE. With increasing life expectancy, prevention of VTE, particularly in elderly patients, will arise as a major public health problem. Few well designed clinical trials evaluating thromboprophylaxis in medical settings were conducted in the specific population of geriatric patients. However, among the several pharmacological treatments evaluated, low molecular weight heparins enoxaparin 40 mg daily or dalteparin 5000 IU daily appeared effective and safe in the prevention of VTE in elderly patients. Despite available data, and recommendations for VTE prevention in medical patients, thromboprophylaxis is underused or misused in practice. Heterogeneity of clinical studies, selected populations, concern about bleeding, and lack of a clear clinical benefit are some of the reasons that could explain the gap between theory and practice. In this review, after a brief report of epidemiologic data and specificities of VTE in elderly patients, the authors discuss the available results of VTE primary prevention trials for elderly medical patients, the limitations of these data, and the challenges to improve the practice and to reduce the incidence of this frequent but preventable disease.