Newer vitamin D formulation appears to help dialysis patients live longer
Patients on paricalcitol have 16 percent better survival than those taking calcitriol

BOSTON - July 30, 2003 - 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, 2003, edition of the New England Journal of Medicine. Led by a Massachusetts General Hospital (MGH) physician, 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 vitamin 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 U.S. patients who receive dialysis for chronic kidney failure, the annual mortality rate is 20 percent. Several approaches have been tried to improve that statistic over the past decade, but few if any have been very successful. Cardiovascular disease is the primary cause of death among dialysis patients, and recently attention has been paid to the impact of hyperparathyroidism - overactivity of the parathyroid gland - on vascular disease.

Part of an imbalance in bone and mineral metabolism that results from kidney failure, hyperparathyroidism is usually treated with intravenous vitamin D therapy. However, treatment with vitamin D may exacerbate cardiovascular disease. Paricalcitol is a vitamin D analog that was approved by the U.S. 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 phorphorous levels, who tend to be resistant to the standard calcitriol, Thadhani and his colleagues decided to analyze whether the newer medication had an impact on 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 January 1, 1999. Of these patients, treated at more than 1,000 Fresenius dialysis centers throughout the U.S., 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. All treatment decisions were made by the treating physicians, as there was no assignment by the research team.

At the end of the study period, the researchers noted a 16 percent better survival among patients taking paricalcitol. Even higher survival rates with paricalcitol were noted among African American patients and diabetic patients - both groups that have higher mortality rates on dialysis than the average. In addition, patients who switched from calcitriol to paricalcitol seemed to live longer than did those that made the reverse switch.

"This is the first study to look at the impact on survival of different types of vitamin D, an important nutrient necessary for normal function," Thadhani says. "While we await verification of these results, we also need to investigate the mechanism behind this improved survival. That could give us more knowledge about how vitamin D is really working and how we might apply these findings to patients before they start dialysis, as well as those who undergo a kidney transplant."

Thadhani is the director of clinical research in kidney diseases at MGH and an assistant professor of Medicine at Harvard Medical School. He and his colleagues note that a randomized, controlled clinical trial of paricalcitol versus calcitriol is required before firm conclusions are made.

Thadhani's co-authors are first author Ming Teng, MD, MS, 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.

Massachusetts General Hospital, established in 1811, is the original and largest teaching hospital of Harvard Medical School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget of more than $350 million and major research centers in AIDS, cardiovascular research, cancer, cutaneous biology, medical imaging, neurodegenerative disorders, transplantation biology and photomedicine. In 1994, the MGH joined with Brigham and Women's Hospital to form Partners HealthCare System, an integrated health care delivery system comprising the two academic medical centers, specialty and community hospitals, a network of physician groups and nonacute and home health services.

Media Contact: Georgia Peirce, MGH Public Affairs

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