August 1 , 2003

Advances
Newer vitamin D formulation appears to help dialysis patients live longer

Dialysis patients taking a particular intravenous vitamin D formulation have a significant survival advantage over patients taking an older and more commonly used form of vitamin D, according to a study published in the July 31 edition of The New England Journal of Medicine. The three-year study found that patients receiving paricalcitol had a 16 percent greater chance of survival than did patients receiving calcitriol. The researchers stress that while this was a large-scale study of dialysis patients living throughout the United States, further studies are required before firm
conclusions can be made.

"This is the first evidence that a specific form of vitaimin D can change the high rate of mortality among dialysis patients," says Ravi Thadhani, MD, MPH, of the MGH Renal Unit, the paper's senior author. "If further research confirms our findings, this will be very important information for dialysis patients and their physicians."

Among the approximately 400,000 US patients who receive dialysis for chronic kidney failure, the annual mortality rate is 20 percent. Cardiovascular disease is the primary cause of death among dialysis patients, and recent attention has been paid to the effect of hyperparathyroidism — overactivity of the parathyroid gland — on vascular disease.
Hyperparathyroidism usually is treated with intravenous vitamin D therapy. Treatment with vitamin D, however, may exacerbate cardiovascular disease. Paricalcitol is a vitamin D analog that was approved by the US Food and Drug Administration in 1998 to treat hyperparathyroidism associated with kidney failure. Because paricalcitol was known to be associated with more stable blood calcium and phosphorous levels and was effective in patients with high phosphorous levels, who tend to be resistant to the standard calcitriol, Thadhani and his colleagues decided to analyze whether the — Newer vitamin D formulation helps dialysis patients newer medication affected patient survival.

The research team — which includes scientists from Fresenius Medical Care North America, based in Lexington, Mass. — followed 67,000 hemodialysis patients who started receiving intravenous vitamin D treatment on or after Jan. 1, 1999. Of these patients treated at more than 1,000 Fresenius dialysis centers throughout the United States, 29,000 started with paricalcitol and 38,000 received calcitriol. During the three-year study, 16,000 patients switched from one vitamin D formulation to another. At the end of the study period, the researchers noted a 16 percent higher survival rate among patients taking paricalcitol. Even higher survival rates with paricalcitol were noted among African-American patients and diabetic patients — both groups that have higher-than-average mortality rates on dialysis.

Thadhani's co-authors are first author Ming Teng, MD, Edmund Lowrie, MD, Norma Ofsthun, PhD, and Michael Lazarus, MD, of Fresenius Medical Care North America; and Myles Wolf, MD, MMSc, of the MGH Renal Unit.