A number of controlled trials have demonstrated that anticoagulant treatment of pulmonary embolism (PE) will reduce the recurrence rate of venous thromboembolism. Pooling symptomatic and asymptomatic cases is usually required to achieve statistical significance. However, recent trials have not demonstrated a reduction in mortality rates when anticoagulant treatment is compared with placebo or when widely varying durations, intensities, and types of anticoagulant therapy are compared. Many of the numerous trials that have failed to demonstrate a reduction in fatal PE have involved large numbers of subjects, suggesting that if such an effect exists it is very small.
Cundiff DK. Does Anticoagulant Treatment Reduce the Mortality of Acute Pulmonary Embolism?. Arch Intern Med. 2001;161(17):2148. doi: