Supplementary Material for: Vitamin K Antagonists Predispose to Calciphylaxis in Patients with End-Stage Renal Disease

Background/Aims: Calciphylaxis is associated with a poor prognosis in dialysis patients, and its pathogenesis remains incompletely understood. Although the use of vitamin K antagonists (VKA) has been implicated, previous reports are conflicting. We aimed to determine if vitamin K antagonists conferred an increased risk of calciphylaxis in patients on dialysis. Methods: We performed a single-centre, retrospective cohort study of 2,234 patients receiving dialysis, and compared the characteristics of those with and without calciphylaxis. Results: We identified 5 cases of calciphylaxis (all female) between January 2009 and December 2013. Overall, 142 patients (6.4%) were treated with VKA during the study period. Calciphylaxis was more common in the VKA group (4 of 142 patients, OR = 61, 95% CI 6.7-546, p = 0.0001). VKA was withdrawn in all cases and treatment instituted with sodium thiosulphate, cinacalcet and supportive measures. All patients recovered, although there was one sudden cerebrovascular death during follow-up. Conclusion: Treatment with VKA predisposes to the development of calciphylaxis.