Kidney disease study zones in on lifetime risk

Kidney disease study zones in on lifetime risk
Alberta research suggests 1 in 40 men, 1 in 60 women will develop end-stage renal failure
CBC News Posted: Aug 16, 2012 5:00 PM ET Last Updated: Aug 16, 2012 4:58 PM ET

The number of Canadians living with kidney failure, a condition that usually requires dialysis, increased steadily over several years, but rates levelled off in 2005. (IStock)

Research on the lifetime risk of kidney failure is "scarce," but now Alberta scientists have a better idea of how many Canadian adults may end up with end-stage renal disease, with men having a much higher chance of developing the chronic condition that poses a heavy cost to individuals and the health-care system.

The 11-year study started in 1997 by Calgary and Edmonton researchers involved 2,895,521 adult Alberta residents (from ages 40 to 80-plus) who were free of kidney failure. The findings, in Thursday's Journal of the American Society of Nephrology (JASN), were released from Washington, D.C.

The researchers analyzed a cohort of Alberta residents who underwent a measurement of serum creatinine — a method of evaluating renal dysfunction. Taking age, gender and their risk of death into account, the lifetime risk of kidney disease for men at age 40 was 2.66 per cent, and 1.76 per cent for women. The risk was higher in the study subjects with reduced kidney function (7.51 per cent for men and 3.21 per cent for women). There was also a graded increase in the risk of renal failure as the study subjects got older.

Some facts about kidney disease:
A variety of diseases and disorders can affect the kidneys. Most attack the filtering units of the kidneys — the nephrons — and damage their ability to eliminate wastes and excess fluids. Chronic kidney disease (CKD) is defined as the presence of kidney damage, or a decreased level of kidney function, for three months or more, and can be divided into five stages.

Usually, kidney disease starts slowly and silently, and progresses over a number of years. Not everyone progresses from Stage 1 to 5, which is known as end-stage renal disease (ESRD) or end-stage renal failure, meaning your kidneys are working at less than 15 per cent of normal, requiring dialysis or kidney transplantation. Source: The Kidney Foundation of Canada

During the followup years, with the mean duration at nearly nine years, 7,107 study participants ended up experiencing kidney failure.

The study concluded that there was a probability of 1 in 40 men, and 1 in 60 women developing kidney failure over their lifetimes.

"Given the high morbidity and cost associated with kidney failure, we wanted to quantify the burden of disease for kidney failure ... to communicate information for patients, health practitioners, and policymakers," researcher Dr. Tanvir Chowdhury Turin of the University of Calgary said in a news release.

Diabetes and hypertension are among the leading causes of kidney failure, which is estimated to affect about two million people globally.

The study points out that estimates of lifetime risk are available for several chronic disease conditions including coronary heart disease, stroke, hypertension (high blood pressure), diabetes, breast cancer, dementia and fractures, but "reports on the lifetime risk of ESRD are scarce, and limited to an early-adult population."

Kidney failure rates level off
According to a report released in 2011 by the Canadian Institute for Health Information (CIHI), the number of people living with kidney failure steadily increased over a nearly 20-year period beginning in 1990, but rates appeared to be stabilizing.

The report said close to 38,000 Canadians were living with kidney failure in 2009, compared to 11,000 in 1990. The largest increase occurred in older age groups, with prevalence rates escalating by more than 500 per cent for those age 75 and older. Patients in that age group account for 20% of all kidney failure cases.

Of Canadians with the disease in 2009, 59 per cent (22,300) were on dialysis and about 3,000 people were on the wait list for a transplant, compared with 53 per cent (5,900) on dialysis in 1990 and roughly 1,600 people on the wait list.

The CIHI report shows the rate of people with kidney failure appears to have levelled off beginning in 2005, something that may be due in part to patients seeing a nephrologist in earlier stages of the disease.

The report also notes that kidney failure results in substantial costs to the health-care system. For example, the cost for dialysis treatment is about $60,000 per patient annually, while the cost for a kidney transplant is about $23,000 plus $6,000 for medication to ensure the body doesn't reject the transplant.

http://www.cbc.ca/news/health/story/2012/08/16/kidney-disease-alberta-study.html