Elevated blood levels of calcium and phosphorus are linked with an increased risk of premature death in kidney disease patients on dialysis, according to researchers at University of Washington, in Seattle.
The Medicare End-Stage Renal Disease Quality Incentive Program is designed to adjust payments to US dialysis facilities based on their performance on a variety of different quality measures that have been included in the program since its inception in 2012. In 2016, the measures will be further expanded to include a 'hypercalcemia' measure, which will penalize dialysis facilities if too many patients have 3-month average blood calcium levels above a certain threshold (10.2 milligrams per deciliter). The change is intended to help address mineral metabolism disorders, which are very common in patients with kidney disease.
To investigate the appropriateness of this new measure, Dr. Matthew Rivara and his colleagues studied whether patients with blood calcium level above the Medicare-identified threshold have a higher risk for premature death compared with patients with lower calcium levels. Their analysis included 129,076 patients on hemodialysis or peritoneal dialysis who were treated between 2001-2006. They found that both low and high blood calcium levels, as well as high phosphorus levels, were linked with an increased risk of dying prematurely in dialysis patients, regardless of the type of dialysis. The research team also found similar results whether or not calcium levels were corrected for the blood protein albumin, which is often done in clinical practice. Finally, the investigators discovered that regardless of type of dialysis, patients with calcium levels above the 10.2 mg/dL threshold have a higher risk of premature death compared with patients with intermediate blood calcium levels.
Researcher Dr. Rivara said, "This last finding is an important first step in the evaluation of this new Medicare quality measure; however, it is critical to point out that no studies, including our own, have shown that use of medications or adjustments in the delivery of dialysis to lower high calcium levels lead to better outcomes for patients. It is possible that high a calcium level may merely be an indicator of a higher risk for poor outcomes, or it may actually be a cause of greater mortality risk."
However, additional studies are needed to test whether interventions that lower calcium levels can improve the health of patients undergoing dialysis.
The study that has been published in the 'Journal of the American Society of Nephrology' (JASN).