Meta-analysis on anticoagulation and prevention of thrombosis and mortality among patients with lung cancer

Background Venous thromboembolism (Wickham et al., 2012 [1]) is a leading cause of morbidity and mortality among patients with cancer; however, primary thromboprophylaxis is not routinely recommended. We performed a systematic review and meta-analysis of randomized control trials (RCTs) to measure the impact of primary VTE prevention and its effect on mortality among patients with lung cancer. Methods With assistance from a master librarian, we searched Ovid, Scopus, DARE, CINAHL, MEDLINE, EMBASE, EBM reviews-Cochrane database of systematic reviews, EBM reviews-ACP journal, and EBM Reviews-Databases for relevant studies following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included articles addressing the role of anticoagulation in patients with lung cancer for primary VTE prevention for outpatients. The clinical outcomes were VTE occurrence, all-cause mortality, major and clinically relevant non-major bleeding. The results are presented as odds ratio (OR) and data were analyzed using R and R META package (Version 0.8–2, Author: Guido Schwarzer). Results Eleven studies with 5107 patients were included for the final analysis. We found 50% lower VTE occurrence in the prophylaxis group with low molecular weight heparin (LMWH) (OR: 0.50; 95% Confidence Interval (CI): 0.38–0.66; I2: 0%) without an increased bleeding risk (OR: 2.03; 95% CI: 0.78–5.25; I2: 71.1%). We found a mortality benefit when we grouped all VTE prevention modalities [LMWH, Warfarin, unfractionated heparin (UFH)] (OR: 0.75; 95% CI: 0.58–0.96; I2: 18.4%), but no significant difference when LMWH (OR: 0.74; 95% CI: 0.49–1.11; I2: 56.9%) and warfarin were analyzed individually (OR: 0.75; 95% CI: 0.47–1.21; I2: 0%). We found higher odds of bleeding combining all treatment modalities (OR: 3.06; 95% CI: 1.64–5.72; I2: 64.4%) with the greatest occurrence in the warfarin group (OR: 5.42; 95% CI: 3.48–8.45; I2: 45.7%). Conclusion Primary VTE prophylaxis with LMWH reduces the occurrence of VTE among ambulatory patients with lung cancer, without apparent increase in bleeding risk. There is a measurable mortality benefit of anticoagulation strategies that remains elusive when the analysis is restricted to a single agent.