Calcium Use in Dialysis Patients with a History of Hypercalcemia, Cardiovascular Calcification, and/or Calciphylaxis

Pharmacy residents have the opportunity to complete a research project during their residency training, which provides them with skills on how to conduct and manage a research project. Projects often represent an area of interest and need that has been recognized by the host institution’s pharmacy department. Projects are presented as a poster at an annual CSHP Ontario Branch Residency Research Night, and many eventually go on to be published in a peer-reviewed journal.Background: The use of calcium salts for the reduction of serum phosphorus levels in chronic dialysis patients increases the risk of hypercalcemia, and may contribute to cardiovascular calcification and calciphylaxis. Newer non-calcium containing binders of phosphorus (NCPBs) may lower these risks, and guidelines recommend restricting the dose of calcium and avoiding hypercalcemia. Objectives: To describe the current prescribing patterns of phosphate binders and to determine (1) the number of dialysis patients who are still receiving calcium-based phosphate binders despite having hypercalcemia, cardiovascular calcification, and/or calciphylaxis (HCCC); (2) potential options for these patients to reduce calcium exposure, and (3) potential reasons for remaining on calcium despite HCCC. Methods: A retrospective chart review was conducted on all chronic hemodialysis and peritoneal dialysis patients at Trillium Health Partners, Mississauga. All active nephrology accounts on February 1, 2019 of patients over the age of 18 were included for data gathering from when the accounts were created. Results: Of the 680 dialysis patients included in the analysis, 79% (n = 537) were prescribed calcium, with the median daily elemental dose for patients with HCCC (n = 528) compared to without HCCC (n = 152) being 1000 mg and 1275 mg respectively. Sixty percent (n = 411) were using calcium despite having HCCC, of whom 78% (n = 319) had the option to start a NCPB or re-evaluate their vitamin D analogue use as a strategy to reduce calcium exposure, while 67% (n = 275) had or were at risk of hypocalcemia, or had potential difficulty accessing NCPBs due to limited insurance coverage. Conclusion: Most dialysis patients still use calcium despite having evidence of complications associated with calcium use. Potential strategies to limit calcium exposure exist, but there are barriers to pursuing these options. These barriers require further evaluation to truly identify the gaps in our care