Dalteparin versus vitamin K antagonists for the prevention of recurrent venous thromboembolism in patients with cancer and renal impairment: a Canadian pharmacoeconomic analysis

BACKGROUND: Patients with cancer are at increased risk of venous thromboembolism (VTE) and the risk is further elevated after a primary VTE. To reduce the risk of recurrent events, extended prophylaxis with vitamin K antagonists (VKA) is available for use. However, in a large randomized trial (Comparison of Low-Molecular-Weight Heparin versus Oral Anticoagulant Therapy for the Prevention of Recurrent Venous Thromboembolism in Patients with Cancer [CLOT]; Lee et al), extended duration dalteparin reduced the relative risk of recurrent VTE by 52% compared to VKA (p=0.002). A recent subgroup analysis of patients with moderate-to-severe renal impairment also revealed lower absolute VTE rates with dalteparin (3% vs. 17%; p=0.011). To measure the economic value of dalteparin as an alternative to VKA, a patient-level cost utility analysis was conducted from a Canadian perspective. METHODS: Resource use data captured during the CLOT trial were extracted and linked to 2015 Canadian unit cost estimates. Health state utilities were then measured using the Time-Trade-Off technique in 24 randomly selected members of the general Canadian public to estimate the gains in quality-adjusted life years (QALYs). RESULTS: For the entire CLOT trial population (n=676), the dalteparin group had significantly higher mean costs compared to the VKA group ($Can5,771 vs. $Can2,569; p<0.001). However, the utility assessment revealed that 21 of 24 respondents (88%) selected dalteparin over VKA, with an associated gain of 0.14 (95% confidence interval [CI]: 0.10-0.18) QALYs. When the incremental cost of dalteparin was combined with the QALY gain, dalteparin had a cost of $Can23,100 (95% CI: $Can19,200-$Can25,800) per QALY gained. The analysis in patients with renal impairment suggested even better economic value with the cost per QALY gained being <$14,000. CONCLUSION: Extended duration dalteparin is a cost-effective alternative to VKA for the prevention of recurrent VTE in patients with cancer, especially in those with renal impairment.