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New index predicts survival for people with severe kidney disease and helps with difficult transplant decisions

March 29, 2010

Scientists from the Ottawa Hospital Research Institute (OHRI) and the University of Ottawa have developed an index that accurately predicts survival in people with end-stage kidney disease. The index uses 12 easily determined factors to measure expected survival both with and without a kidney transplant. It was developed by Dr. Carl van Walraven and Dr. Greg Knoll, using data from nearly 170,000 U.S. patients who were placed on a kidney transplant wait list or who received a transplant between 1995 and 2006. It is published in the Canadian Medical Association Journal.

“We’ve known for a long time that kidney transplants improve survival, however, it is difficult to predict how big the effect will be for an individual patient,” said Dr. van Walraven. “This tool will let us make objective personalized predictions so that patients can make more informed decisions about transplantation.”

The researchers developed the index by measuring the relationship between various patient characteristics and survival using the United States Renal Data System. As expected, the factors that had the greatest effect on survival were transplantation status and age. Other factors that had a significant effect were race, smoking status, employment status, body mass index, other diseases present, the level of a common blood protein, year of first dialysis, number of months on dialysis before being placed on a transplant waiting list and number of years on the waiting list.

The researchers assigned various numbers of points to each of these factors. The total score for a particular patient accurately predicts their risk of dying within five years from any cause. The risk of dying ranged from a low of 1.7 per cent to high of 75.3 per cent. The researchers also developed a calculation tool (available upon request) that makes it easy to input the 12 factors and quickly determine an individual’s risk of death, both with and without a transplant. Survival can also be calculated with a transplant from a living donor versus a deceased donor.

“In some people, a transplant might cut the risk of dying in half. But the presence of certain risk factors in other people could either magnify or dampen this effect,” said Dr. van Walraven. “Knowing this can help with difficult transplant decisions, especially when patients are also considering quality of life issues, such as the effects of drugs that must be taken to prevent transplant rejection.”

Dr. van Walraven is a senior scientist at OHRI, an internal medicine specialist at The Ottawa Hospital and a professor of medicine at the University of Ottawa. Dr. Knoll is an associate scientist at OHRI, the medical director of kidney transplantation at The Ottawa Hospital and an associate professor of medicine at the University of Ottawa. Dr. Peter Austin, a senior scientist at the Institute for Clinical Evaluative Sciences and an associate professor at the University of Toronto, is also an author on the paper.

About OHRI
The Ottawa Hospital Research Institute (OHRI) is the research arm of The Ottawa Hospital and is an affiliated institute of the University of Ottawa, closely associated with the University’s Faculties of Medicine and Health Sciences. The OHRI includes more than 1,500 scientists, clinical investigators, graduate students, postdoctoral fellows and staff conducting research to improve the understanding, prevention, diagnosis and treatment of human disease. www.ohri.ca

Media contact
Jennifer Paterson
Director, Communications and Public Relations
Ottawa Hospital Research Institute
613-798-5555 ext. 73325
jpaterson@ohri.ca