Low molecular weight heparin administered once versus twice daily in patients with venous thromboembolism - A meta-analysis

Background. Low molecular weight heparin is as effective and safe as unfrac tionated heparin for treatment of acute venous thromboembolism. It is uncer tain whether low molecular weight heparin should be administered once-daily or twice-daily in this setting. Method. A metaanalysis of randomized studi es which directly compared once- and twice-daily administration of low mole cular weight heparin for the treatment of acute venous thromboembolism was performed. A literature search was performed using Advanced Pub Med and the Cochrane library database, and abstracts from recent meetings were reviewe d. Two investigators extracted data independently. Results. Five studies, i nvolving 1522 patients, were eligible. There were no statistically signific ant differences in the frequencies of symptomatic (odds ratio, 0.85 in favo r of once-daily therapy at three months, p = 0.6), and asymptomatic, recurr ent venous thromboembolism; total and major bleeds (odds ratio, 1.16 in fav or of twice-daily therapy at 10 days, p, = 0.8); and death, at 10 days, as well as at three months of follow-up. Conclusion. Once-daily low molecular weight heparin appears to be as effective and safe as twice-daily administr ation for the acute treatment of venous thromboembolism. However, there is inadequate data from studies that directly compared once-daily and twice-da ily administration to be able to exclude the possibility of a higher freque ncy of fatal bleeding with once-daily therapy.