Supplementary Material for: The Effectiveness of Topical Cerium Nitrate-Silver Sulfadiazine Application on Overall Outcome in Patients with Calciphylaxis

<b><i>Background:</i></b> Calciphylaxis (CPX) is a rare and life-threatening disease characterized by vascular calcification and development of painful and necrotizing skin lesions with a challenging management. Mechanisms of CPX are complex and include an imbalance between vascular calcification promoters and inhibitors, and frequently vitamin K deficiency. <b><i>Objectives:</i></b> To describe the various presentations and identify predictive factors of death in patients with CPX. <b><i>Methods:</i></b> In this multicenter retrospective study, we included 71 CPX patients followed in South-West France (<i>n</i> = 26) and in French Polynesia (<i>n</i> = 45), and who all received sodium thiosulfate (25 g thrice weekly for a median of 61 days). <b><i>Results:</i></b> Characteristics at presentation significantly differed between metropolitan and Polynesian French patients. Polynesians were less frequently on regular dialysis at the onset of CPX, had a higher incidence of diabetes mellitus and obesity, more disturbances of calcium-phosphorus metabolism, and received vitamin K antagonists less frequently than patients from South-West France. Despite intensive management, the 1-year mortality rate was 66% and median time to death was 200 days (IQR, 40; 514). The number of body areas involved (i.e., three: OR 2.70 [1.09; 6.65], <i>p</i> = 0.031; four: OR 8.79 [1.54; 50.29], <i>p</i> = 0.015) was the only predictive factor for death, whereas application of topical cerium nitrate-silver sulfadiazine was protective (OR 0.44 [0.20; 0.99], <i>p</i> = 0.046). Surgical debridement, hyperbaric oxygenation therapy, and geographical origin were not associated with overall outcomes. <b><i>Conclusions:</i></b> Cerium nitrate may lead to vascular decalcification and chelation of reactive oxygen species, and prevent infection. Cerium nitrate-silver sulfadiazine was associated with better outcomes and should be tested in a prospective comparative trial in CPX patients.