Venous thromboembolism [VTE] is the second highest cause of mortality among patients with cancer. However, pharmacological thromboprophylaxis for patients with solid tumor is only recommended during hospitalization. Primary outpatient thromboprophylaxis is not a widely accepted practice.
Determine safety and efficacy of outpatient primary VTE prophylaxis in patients with solid tumors.
A systematic review was conducted using MEDLINE and EMBASE up to June 2012. Key search words included venous thromboembolism, malignancy, anticoagulants, and chemotherapy. Studies were considered for our meta-analysis if they included outpatient primary pharmacological thromboprophylaxis in adult patients with active solid cancer. All the information was independently reviewed by 2 of the authors [MP, SJ] and a third reviewer resolved discrepancies. The measure of association was calculated with R (R: A Language and Environment for Statistical, R Development Core Team, www.R-project.org), R META package (Version 0.8–2, Author: Guido Schwarzer). The Q statistic was calculated and a formal test of homogeneity was conducted. Random-effects model was preferred in case of heterogeneity.
A total of 1371 abstracts were reviewed and 29 manuscripts were fully abstracted. Eight randomized controlled trials including 6706 patients were analyzed. There were less VTE events with outpatient prophylaxis: odds ratio [OR] of 0.53 (95% CI, 0.40–0.70). Six studies used low or ultra-low molecular weight heparin and two studies used warfarin. In the subgroup analysis of heparin based primary prophylaxis, there was a significant reduction in VTE events [OR 0.47, 95% CI, 0.34–0.64], no significant heterogeneity [FIG 1]. In addition, there was no difference in major bleeding events between groups [OR 1.48, 95% CI, 0.89–2.46]. Five studies reported mortality data; there was significant heterogeneity between studies.
Heparin based outpatient VTE prophylaxis in patients with solid tumors reduced by half the risk of VTE with no significant differences in major bleeding events. The current publications do not allow a meaningful grouped analysis of survival data, improved patient selection is necessary in order to adequately target VTE prevention strategies.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.