Which of the following statement(s) is/are true concerning the results of a National Institute of Health Consensus Conference on venous thrombosis and low-dose heparin prophylaxis?

a. The odds of developing deep venous thrombosis with low-dose heparin prophylaxis decreases by 67%

b. The risk of pulmonary embolism is decreased by almost 50%

c. There is no increase in mortality from other causes found in patients treated with low-dose heparin

In a metaanalysis of 70 randomized trials in 16,000 patients comparing low-dose heparin prophylaxis with standard therapy, the odds of developing deep venous thrombosis with low-dose heparin prophylaxis decreased 67%, whereas for pulmonary embolism (both fatal and non-fatal), the odds decreased by 47%. For fatal pulmonary embolism, the odds reduction was even greater (64%). No increase in mortality from other causes was found in those patients treated with low-dose heparin. Bleeding complications were more frequent in the heparin-treated patients, with no difference between 5000 units twice daily and 5000 units three times daily. Similarly, the effectiveness of prophylaxis was not influenced by either two or three times daily dosage.