#2435 Calciphylaxis: patient demographics, risk factors and outcomes in a single regional centre in New Zealand

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Abstract Background and Aims Calciphylaxis, a condition associated with microvascular calcification and subsequent formation of non-healing tender skin lesions, has previously been estimated to affect only approximately 1% of patients with ESRD each year. However, clinicians practicing in a regional renal unit in the North Island of New Zealand have noted an increase in the frequency of clinical diagnoses of this condition over recent years. The aim of this review was to analyze patient demographics and risk factors and attempt to identify any correlation with subsequent outcomes. Method A cross sectional retrospective review of dialysis patients from Palmerston North Hospital's Renal Unit who were found to have diagnoses of calciphylaxis, was performed. The following factors were assessed: gender, ethnicity, smoking status, diabetes, obesity, hypertension, dialysis modality, prescription of phosphate binders, vitamin D analogues, and sodium thiosulphate (STS). We included patients with both histologically proven calciphylaxis and clinical diagnosis only. Levels of serum PTH, calcium and phosphate at the time of diagnosis were reviewed, though only PTH levels were included in the final analysis. Results A total of nineteen patients were identified having calciphylaxis as a diagnosis in the period studied. Findings were limited due to the small patient cohort size, but of those identified and reviewed some commonalities were found. Included were 9 NZ European people and 8 NZ Māori people. There were 8 females. One patient was a current smoker at time of diagnosis and five were documented as ex-smokers. Fourteen patients (74%) had type 2 diabetes mellitus and hypertension. Twelve patients (63%) were obese. Eighteen patients (95%) had hyperparathyroidism. Warfarin use was seen in 10 of the patients studied (52%) and twelve (63%) had used phosphate binders. Nine patients (47%) were diagnosed in the period between 2011 and 2021, with the remaining ten (53%) diagnoses occurring in 2022 or 2023. The majority (90%) were treated with STS, however 84% died. Dialysis modality at time of diagnosis and throughout disease span was also reviewed. Eight patients (42%) used only haemodialysis (HD), six patients (32%) used both modalities and five patients (26%) used only peritoneal dialysis. The majority (63%) of patients were on haemodialysis at time of diagnosis. Conclusion Calciphylaxis appears to be increasing dramatically in the single center studied in this review. Positive correlations were identified between high levels of PTH, obesity, hypertension, type 2 diabetes, and use of warfarin. Unfortunately, due to small case numbers, and poor historical documentation, further conclusions could not be drawn easily. A further RCT would be required to investigate the efficacy of STS as a treatment for calciphylaxis.