Avoiding a kidney calamity: A matter of numbers

Just a few years ago, kidney care did not rank high on the priority list of family physician Chester Fox, MD. That changed after he participated in a National Kidney Foundation event designed to raise awareness about what primary care physicians can do for patients who have chronic kidney disease. As a result, he decided to review his charts and think more carefully about the role this organ played in his patients' overall health.

"I started looking at my hypertensives and diabetics, and it was scary," said Dr. Fox, professor of clinical family medicine at the University at Buffalo -- State University of New York. "I thought I was doing a decent job, but I was ignoring elevated creatinines. A lot of them had mild anemia that I was ignoring."

He now speaks regularly on why kidney care is important to primary care physicians and is one of a growing number of non-nephrologists who are paying more attention to it because of a convergence of population-wide health trends and new data suggesting that early action is both feasible and important.

One of the most notable factors driving interest is the sheer number of people who have some form of kidney disease. According to a study published in the January 2003 American Journal of Kidney Diseases, an estimated 19.2 million people have some form of it. The number of patients on dialysis or in need of a transplant is approaching half a million and increasing approximately 4% per year, according to the U.S. Renal Data System, which tracks end-stage kidney disease.

"It's been unappreciated that it's as prevalent as it is," said Anton Schoolwerth, MD, MSHA, a nephrologist at Dartmouth-Hitchcock Medical Center in Lebanon, N.H., who is consulting with the Centers for Disease Control and Prevention on the possibility of related public health activities.

That prevalence has highlighted the need to widen the net in terms of diagnosis and treatment. State programs that fund care for end-stage kidney disease regularly run out of money, and nephrology organizations are increasingly asking primary care physicians and other specialties to share in treating this population.

"There are just too many patients out there with chronic kidney disease. It will be impossible for nephrologists to care for them all," said Mark Rosenberg, MD, director of the division of renal diseases and hypertension at the University of Minnesota in Minneapolis. He gave a presentation on this issue at the American College of Physicians meeting in Philadelphia earlier this year.

Many experts blame the increasing numbers on the rise in obesity, which is leading to soaring rates of diabetes and hypertension. Not only are more people developing these conditions, but they are living long enough -- because of improvements in care -- to develop kidney complications and other downstream effects.

Another explanation is that testing for earlier forms of kidney disease has become easier.

But incident rates are not the only reason nephrologists are asking for assistance. Evidence is mounting that even minor kidney complications are significant and that care needs to occur in the early stages.

"Any intervention that we do that will be meaningful for the patients, society and public health will be early intervention, and early intervention means that the patients have not yet been referred to a specialist," said Arnold Berns, MD, co-chair of the American Society of Nephrology's Practicing Nephrologists Advisory Group and clinical professor of medicine at the University of Illinois College of Medicine in Chicago.

The vast majority of those with chronic kidney disease never reach the late stages because they die of cardiovascular disease when damage to the heart is accelerated by damage in the kidneys. Most recently, a study published in the September Diabetes Care found that those with type 2 diabetes who had kidney disease, even if it was very mild, had a significantly increased risk of death, mostly from heart disease.

"Patients die before they can develop end-stage kidney disease, but yet they have chronic kidney disease as the underlying and overarching problem accelerating their cardiovascular disease," said Craig B. Langman, MD, head of the division of kidney disease at Children's Memorial Hospital in Chicago.

The heart-kidney link is not fully understood, but it is being acknowledged by organizations outside the kidney field. The American Heart Assn. issued a scientific advisory in August saying that all cardiovascular disease patients should have their kidney function assessed.

"Because kidney disease is a risk factor, it's important to know that in patients who are either at risk or have proven cardiovascular disease because you'll want to intervene to try and modify that just like you'd modify other risk factors," said Frank Brosius, MD, lead author of the advisory and division chief of nephrology at the University of Michigan, Ann Arbor.

Positive signs

The good news, though, is that it has become more possible than ever to detect kidney disease and interrupt its course, particularly in the primary care setting.

"For most of my career, the feeling was that if someone gets chronic kidney disease, then there's an inexorable march towards kidney failure," said Susan Snyder, MD, vice chair of the department of family medicine at Harbor-UCLA Medical Center. "We now know that there are a number of interventions that can really slow down the progression. There's more and more reason to find it early and intervene."

Detection, once the disease starts, is fairly straightforward. The days of needing a 24-hour urine collection to assess kidney function are over for most patients. The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative guidelines, the most widely accepted, recommend using the estimated glomerular filtration rate, or eGFR, which is frequently included routinely as a part of a metabolic panel. Even if it isn't, serum creatinine almost always is, and this number can be plugged into a formula widely available online to get the eGFR. Proteinuria can also be detected with a dipstick test in a random urine sample.

"It's just a very feasible thing to test," said Michael Shlipak, MD, MPH, division chief of general internal medicine at the San Francisco VA Medical Center, who has been researching markers for pre-clinical kidney disease.

Taking action in response to the eGFR is also relatively uncomplicated. Prevention before kidney damage occurs requires the same lifestyle interventions needed for overall health. When kidney damage becomes apparent, treatment may not be radically different from what is already being done for the patient's other conditions, although it does become more important to reach various treatment goals.

"If someone is identified as having chronic kidney disease, that is a really strong motivating factor for being particularly aggressive," said Andrew S. Narva, MD, director of the National Kidney Disease Education Program run by the National Institute of Diabetes and Digestive and Kidney Diseases.

Anemia and bone disease related to kidney dysfunction should be looked for and attended to. Dyslipidemia should be treated aggressively. Blood pressure control for those who have hypertension and blood sugar control for those with diabetes both should be tightened. But the kidney needs to be considered in all treatment decisions. Specifically, some medications should be avoided while others are preferred.

"This population is different enough that once you find it, the targets are different," said Allan J. Collins, MD, NKF president-elect and director of the renal data system.

For example, diuretics are often the first-line treatment for many patients with hypertension, but for those who also have evidence of kidney damage, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may be the better course.

"ACE inhibitors and ARBs have kind of revolutionized the ability of primary care doctors to make a positive difference in early kidney disease," said Terry L. Mills, MD, a family physician in Newton, Kan. "They've made it easy."

Obviously, detection and treatment are very feasible. It is the barriers to addressing the problem once diagnosed that can be significant. Primary care medical societies are providing more educational sessions, but several studies have suggested that many physicians are not aware of the NKF guidelines.

"A lot of education is needed," said Dr. Snyder. "We have to work on the attitude that there's nothing to do about chronic kidney disease, because there is a lot to do now."

Kidney function can also decline without producing any symptoms until significant intervention is needed. Thus, it may not be something that patients ask about in the early stages. It can also get lost in the myriad of other things that need to be done in a primary care visit.

"Primary care physicians are dealing with multiple medical problems and tend to have patients with multiple chronic illnesses, of which kidney disease is just one of those," said L. Ebony Boulware, MD, MPH, assistant professor of medicine and a general internist at Johns Hopkins University in Baltimore.

Many experts have great hopes. They are encouraged by the level of attention being paid to patients at the early stages and expect it will lead to fewer patients being placed on dialysis or in need of a transplant. More importantly, they see the earlier action leading to reductions in the number of deaths linked to kidney damage. Anecdotal evidence suggests this may be possible. Before Dr. Fox began focusing on kidney care, patients he referred to nephrologists would generally end up on dialysis almost immediately. This is no longer the case.

"I was able to change my practice very rapidly in six months and do a much better job of caring for chronic kidney disease," he said. "The last three patients I sent to the nephrologists who were supposed to need dialysis have all stabilized. That may just be a lucky streak, but it's very gratifying."