Anticoagulant use in patients with cancer associated venous thromboembolism: A retrospective cohort study

Abstract

IntroductionLong term anticoagulant therapy is recommended for treatment and secondary prevention of venous thromboembolism in cancer patients. We assessed outpatient anticoagulants [warfarin, low molecular weight heparins (LMWHs), fondaparinux and unfractionated heparin (UFH)] use in adult, cancer patients, 20years of age or older, who incurred a venous thromboembolism (primary or secondary in-hospital diagnosis) in Quebec, Canada between 2007 and 2009. Materials and methodsData were obtained from the Quebec Health Insurance Agency. Patients with an in-hospital cancer diagnosis between April 2007 and June 2009 and an in-hospital venous thromboembolism diagnosis either concurrently or consequently were eligible at the date of discharge (index date). Those patients registered with the provincial drug plan and discharged to the community were included in the study and followed for 6months. ResultsAmong 2,070 study patients, 72.4% received anticoagulant therapy at index date, 60% of whom were persistent with therapy and received it for ≥80% of follow-up days. Outpatient anticoagulant use was more likely in those with primary versus secondary diagnosis of venous thromboembolism and less likely in patients with cerebrovascular disease, peptic ulcer disease or previous anticoagulant use. The small number of patients who used either UFH (n=11) or fondaparinux (n=5) at index date were included in the LMWH group. Warfarin use was less likely than LMWH use in corticosteroid users, previous anticoagulant users, patients with metastatic cancer and those with catheter or chemotherapy in the previous three months. Warfarin use was more likely than LMWH use in: older patients, those residing in rural areas, those with lower income and those suffering from ischemic heart disease, atrial fibrillation or chronic kidney disease. Patients with ischemic heart disease were more likely to have used a non-dalteparin LMWH versus dalteparin (currently, the only LMWH approved by health Canada for chronic treatment of VTE), while those residing in rural areas and those with catheter/chemotherapy were less likely to have used them. A primary (versus secondary) discharge diagnosis of venous thromboembolism [Odds Ratio 1.42; 95% confidence interval (1.14, 1.76)], and metastatic cancer 1.27 (1.00, 1.60) were associated with persistence on anticoagulant treatment. ConclusionGuideline recommended outpatient use of anticoagulant in cancer patients hospitalized with venous thromboembolism was influenced by cancer status, old age and low income. Risk factors for bleeding prevented outpatient anticoagulant use in some patients.