This study was appropriately powered to detect the treatment effect reported by the authors. Typically, anticoagulation is discontinued in this specific patient population once the risk of bleeding and/or the patient’s perceived inconvenience of therapy outweighs the expected benefit from continuing treatment to prevent VTE recurrence. Study results suggest aspirin is effective in preventing recurrence while not conferring an increased risk for hemorrhage. It is important to note that patients with cancer and symptomatic atherosclerosis were excluded from this study.
Bottom line: Following an appropriate treatment period with standard anticoagulation, aspirin appears to be a safe and effective therapy in the secondary prevention of recurrence in patients with a history of unprovoked VTE.
Citation: Becattini C, Agnelli G, Schenone A, et al. Aspirin for preventing recurrence of venous thromboembolism. N Engl J Med. 2012;366(21):1959-1967.
Meta-Analysis Supports New Oral Anticoagulants in Patients with Atrial Fibrillation
Clinical question: Are novel oral anticoagulants both efficacious and safe in comparison to warfarin in patients with atrial fibrillation (afib)?
Background: Three large clinical trials recently evaluated novel oral anticoagulants (dabigatran, rivaroxaban, and apixaban) as alternatives to warfarin in afib patients. Although the anticoagulants all appeared efficacious for primary outcomes, results regarding secondary and safety outcomes were either inconclusive or heterogeneous.
Study design: Systematic review and meta-analysis of randomized controlled trials.
Setting: Three diverse, clinical-trial settings.
Synopsis: A systematic review and meta-analysis of randomized controlled trials comparing novel oral anticoagulants to warfarin in afib patients found three large studies examining dabigatran, rivaroxaban, and apixaban that included 44,563 patients.
Using random-effects models to pool data from these studies, the authors found a 22% relative risk (RR) reduction of stroke or systemic embolism with the use of these new anticoagulants as compared to warfarin. The risks for ischemic and unidentified stroke (RR 0.87), hemorrhagic stroke (RR 0.45), intracranial bleeding (RR 0.49), and mortality (RR 0.88) were significantly reduced in patients taking these new anticoagulants. There was no significant reduction in major bleeding.
A trend in favor of warfarin was seen for gastrointestinal bleeding, but this trend was not statistically significant (RR 1.25; 95% confidence interval, 0.91-1.72).
This meta-analysis was limited to only three randomized controlled trials, each comparing a different oral anticoagulant to warfarin and using somewhat heterogeneous study designs and patient populations.
Bottom line: Three new oral anticoagulants appear safe and more efficacious than warfarin in the prevention of stroke and systemic embolism, as well as other important clinical outcomes in patients with atrial fibrillation.
Citation: Miller CS, Grandi SM, Shimony A, Filion KB, Eisenberg MJ. Meta-analysis of efficacy and safety of new oral anticoagulants (dabigatran, rivaroxaban, apixaban) versus warfarin in patients with atrial fibrillation. Am J Cardiol. 2012;110(3):453-60.
Observational Study Suggests Intravenous Metronidazole May Be Inferior for Mild Clostridium Difficile Infection
Clinical question: How do different treatment regimens (oral metronidazole vs. intravenous metronidazole vs. oral vancomycin) for mild Clostridium difficile infection (CDI) compare with regard to clinical outcomes?
Background: CDIs are increasing. Oral metronidazole or vancomycin can be used for the initial treatment of non-severe CDI. Additionally, a paucity of clinical data exists on intravenous metronidazole, which is used in some cases, typically in combination with vancomycin and in patients with severe CDI.
Study design: Prospective cohort study.
Setting: International hospital-based study.
Synopsis: This observational study assessed three different regimens (oral metronidazole, intravenous metronidazole, and oral vancomycin) for the treatment of mild CDI in 265 inpatients. Mortality at 30 days was higher in the intravenous metronidazole group (38.1%) than in the oral metronidazole (7.4%) and vancomycin (9.5%) groups. Patients receiving intravenous metronidazole also were less likely to recover from disease (52.4% versus >80% in the oral metronidazole and vancomycin groups). No statistically significant differences for other sequelae of CDI were found, except for higher risk of dehydration in the oral vancomycin group.