Policy & Public Affairs
Earlier Kidney Testing Urged
By Beth Baker
Special to The Washington Post
Tuesday, February 5, 2002
This article can be found at www.washingtonpost.com/wp-dyn/articles/A22920-2002Feb4.html
Alarmed by the steep rise in the number of Americans with kidney failure -- now estimated at 340,000, up from 183,000 a decade years ago -- the nonprofit National Kidney Foundation this week released new guidelines calling for earlier screening for the disease.
The guidelines, developed by a work group that included experts in kidney disease, epidemiology, laboratory medicine, nutrition, gerontology and social work, aim to catch new cases when they can still be treated with drugs and lifestyle changes instead of more drastic and costly measures like dialysis and transplant, the only options available later. Published in the February issue of the American Journal of Kidney Diseases, the guidelines are the culmination of two years' work reviewing evidence published in peer-reviewed medical journals.
To aid patients and practitioners in recognizing and treating chronic kidney disease earlier, the guidelines identify five stages of the illness, from mildest to most severe. Previously, only patients diagnosed with kidney failure -- meaning they need dialysis or a kidney transplant to survive -- were classified as having kidney disease.
Thomas Hostetter, director of the kidney disease education program at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), commended the guidelines for "call[ing] attention to the problem and provid[ing] some kind of organized nomenclature and approach to it."
Most dialysis and kidney transplant expenses are borne by Medicare -- regardless of the age of the patient -- which currently spends nearly $18 billion a year on such care, according to the Kidney Foundation. Because of the aging of the American population and the increased prevalence of high blood pressure and diabetes, the number of patients with kidney failure is projected by the U.S. Renal Data System to nearly double to 650,000 by 2010, costing taxpayers $28 billion annually.
"The number of patients on dialysis has been increasing exponentially for almost three decades," said Josef Coresh, an epidemiologist at Johns Hopkins University in Baltimore. "It's likely to continue."
In most cases of chronic kidney disease, there is a gradual loss of function before the kidneys fail altogether. It is this slow decline that the new approach hopes to detect.
Under the Kidney Foundations new guidelines, which includes people in the early stages of the disease, nearly 20 million Americans are estimated to have chronic kidney disease -- and most are unaware of it. Because there typically are no symptoms until the disease is far advanced, only by undergoing lab tests will most people learn that they have the disease. Another 20 million people are at increased risk of getting the disease.
Left untreated, kidney disease can be deadly. The kidneys filter the bloodstream of wastes, which combine with water to form urine. When the kidneys fail, the wastes accumulate in the body and cause death within weeks, unless the person undergoes dialysis -- an hours-long process in which a machine filters the blood, typically several times a week -- or receives a kidney transplant.
"We now realize that earlier stages of the disease are much more common than previously thought," said Andrew Levey, chief of nephrology at the New England Medical Center in Boston, who chaired the work group. "If the diagnosis is made earlier and if kidney disease is treated earlier, some of the complications of chronic kidney disease can be prevented, including the progression to kidney failure and the development of heart disease," which is a common outcome of kidney disease.
Those most at risk of developing chronic kidney disease, including the millions of people with diabetes, high blood pressure or a family history of the disease, are the primary focus of the new guidelines. The high-risk group also includes older Americans and African Americans, Asian and Pacific Islanders, American Indians and Hispanics.
People in these groups are urged to get three simple tests during their regular physical: a blood pressure check; an estimate of glomerular filtration rate, or GFR (the best measure of kidney function, this blood test measures the rate at which waste is filtered); and a dipstick test for protein in the urine. (Proteinuria, excretion of unusually large amounts of protein, is an indicator of kidney damage.)
While conventional wisdom among physicians has long held that proteinuria and GFR could best be determined by asking the patient to collect a 24-hour urine sample, the work group found that blood and urine samples during a routine office visit provide accurate measures.
Under the new classification system, a person deemed to have Stage 1 disease has some kidney damage (as measured by proteinuria or some other marker) and a GFR of 90 ml/minute or higher. (A GFR of 100 to 120 is considered normal.) Each successive stage is linked to a lower GFR number; by Stage 5, kidney failure, the filtration rate is 15 or less.
If the screening tests indicate kidney disease, the patient will be monitored or, if warranted, treated with medication or taught dietary or other lifestyle changes, depending on the cause of the disease. Two common causes are high blood pressure and diabetes.
The guidelines also highlight some glaring gaps in knowledge, said Hostetter. Most notable among these: What happens to the 19-plus million people in the United States who have kidney disease but don't know it? "It may be they die prematurely from cardiovascular disease, but that's just a guess," he said. To help answer this question, the National Institutes of Health is conducting a seven-year study of 3,000 people with Stage 2, 3 or 4 chronic kidney disease to see how they fare.
Together, members of the Kidney Foundation group and the NIDDK program plan to develop simple messages for the public and for family physicians. One idea is to use the slogan "Know your number" to encourage people at risk of kidney disease to learn what their GFR level is, just as those with heart disease learn their blood pressure and cholesterol levels.
Experts say it's important for patients to be vigilant and not assume testing isn't necessary simply because their doctor hasn't recommended it. Family physicians are overwhelmed by messages from other medical specialists and disease groups, said Cynda Johnson, chairwoman of the Department of Family Medicine at University of Iowa, who served on the Kidney Foundation work group.
"From the family physician's point of view, we've got so many words coming out at us, we can't see straight," she said.
It's not only doctors and patients who will need to be educated to detect kidney disease earlier. Medical labs, for example, will be urged to adjust their computers to generate GFR data from blood tests that measure levels of creatinine, another component of urine that measures kidney function. In fact, the Kidney Foundation recommends that labs automatically figure the GFR on all blood creatinine tests ordered during routine physicals, even for patients who are not at risk of kidney disease.
"We'll also meet with HMOs and insurance companies to show them how these tests can be done, how it can affect patient outcomes and in the long run save money," said Garabed Eknoyan, professor of medicine at Baylor College of Medicine in Houston and a leader of the Kidney Foundation's efforts to improve clinical practice guidelines.
The guidelines will be posted on Kidney Foundation's Web site at www.kidney.org. Click on K/DOQI.
Beth Baker is a frequent contributor to the Health section.