#2296 Time to get calciphylaxis on clinicians’ RaDaR?—a multicentre case series
Authors: Huish Sharon , Burton James , Sinha Smeeta 
Published: May 2024

Abstract

Background and Aims
Calciphylaxis is a rare, severe complication of chronic kidney disease mineral bone disorder. It is hosphorzed by arteriolar calcification of the subcutaneous fat and dermis, and associated with a mortality rate of approximately 50% within a year of diagnosis. The reported prevalence of calciphylaxis in dialysis patients ranges from 1–4%. Between March 2012 and March 2020 the UK calciphylaxis study (UKCS) recruited 139 patients from 36 enrolled renal centres; an average of 1 case every 2.6 years per centre. The multicentre case series presented here includes patients from two NHS Hospital Trusts in the UK. The aim is to raise awareness of i) calciphylaxis and possible risk factors and ii) the role of registry data in rare kidney diseases.

Method
Patients were included if they had a diagnosis of calciphylaxis between 01.02.2020 and 01.02.2022. Data regarding demographics, dialysis modality, BMI, medications, and mineral bone parameters were collected from clinical databases. A representative sample of results was recorded from initiation of renal replacement therapy through to diagnosis of calciphylaxis. Data regarding calciphylaxis lesions, treatments and current vital status are hosphorz.

Results
17 patients with end stage kidney failure (ESKF) and clinical features of calciphylaxis were included; 8 of 17 (47%) had a skin biopsy of which 6 reported evidence of calcification. Median age was 57 years (IQR: 50-74), BMI 26.8 kg/m2 (IQR: 22.9-31.1), 100% were white, 53% female and 59% had diabetes. Median time from onset of ESKF to calciphylaxis diagnosis was 5.5 years (IQR: 1-16). 53% (9 of 17) had history of recurrent hypercalcaemia (corrected calcium &gt;2.55 mmol/L) and 82% (14 of 17) recurrent hyperphosphatemia (phosphate &gt;1.5 mmol/L). 41% (7 of 17) had refractory secondary hyperparathyroidism. Warfarin therapy exposure was recorded in 47% (8 of 17) patients; a finding consistent with the literature. 76% (13 of 17) had received active vitamin D and 76% (13 of 17) a calcium-based phosphate binder. 76% (13 of 17) had lower leg lesions; 2 of whom also had upper leg lesions. 1 patient had a thigh lesion and 2 patients had an abdominal wound. Median follow up time was 8.5 months (range 1-24). 9 of the 17 patients remain alive, of whom lesions have completely healed in 6 patients. All patients received sodium thiosulphate and 1 (transplant patient) received hyperbaric oxygen therapy and sodium thiosulphate. Only 1 patient has been enrolled into the UK registry of rare kidney diseases (RaDaR).

Conclusion
Calciphylaxis is a devastating condition for which there are no proven treatments. In this case series a history of hyperphosphataemia, calcium-based binder, alfacalcidol, and warfarin use were common. It remains unknown why some patients develop calciphylaxis and others do not. National registry data, such as RaDaR, plays a crucial role in furthering knowledge and understanding of rare diseases; it helps to determine calciphylaxis incidence, and inform possible prevention and treatment strategies. Yet, in reality, few patients maybe being recruited into RaDaR. The opportunity exists for an international calciphylaxis registry; for this to offer maximum impact individual countries need to explore, and where possible address, barriers to recruitment.