More than 20 million Americans have chronic kidney disease (CKD), but both patients and providers often fail to recognize the disease until it has advanced, thereby missing opportunities to delay the need for expensive, life-altering care such as dialysis and transplantation.
Part of the problem is that many generalist physicians are unclear of the warning signs that patients may be at risk for CKD, and many tend not to use the most appropriate diagnostic tests to assess kidney function. There is even evidence that for patients who have both CVD and CKD, physicians may be reluctant to prescribe the very treatments that would be effective in treating both conditions.1
The National Kidney Foundation is addressing the problem with an enhanced screening effort aimed at identifying more cases of CKD at an earlier stage.
Further, given the extreme shortage of nephrologists in the United States, the group also stresses that generalist physicians need to equip themselves with the knowledge to not only recognize CKD, but also to effectively treat the condition, at least in its earlier stages.
Screening is essential
Patients are unlikely to recognize CKD because it is largely asymptomatic in its early stages, and even after the condition has advanced, symptoms such as ankle swelling or fatigue do not necessarily suggest to patients that there is a problem with kidney function.
Consequently, it is even more important that generalist physicians understand that they need to screen for CKD in patients who are at risk for the condition.
This encompasses a relatively large group, including patients over the age of 65 and those with
Most experts agree that the most accurate way to screen for CKD is to obtain the estimated glomerular filtration rate (GFR), which is a measure of how effectively the kidneys remove waste and excess fluid from the blood. However, to obtain the GFR, providers need to take the patient’s serum creatinine level and enter that number into an equation that also incorporates the patient’s age, race, and gender.
The means to carry out this calculation are widely available. In fact, many Web sites, including www.kidney.org, offer a tool that allows providers to simply enter the appropriate data for a patient, and the tool automatically carries out the calculation.
However, many physicians do not take this step, preferring to just look at the serum creatinine level—a less accurate measure that can also create confusion, says Joseph Vassalotti, MD, chief medical officer of the National Kidney Foundation, and assistant clinical professor in the Division of Nephrology at Mount Sinai School of Medicine in New York City.
“The problem with the serum creatinine test is that it has an inverse, reciprocal relationship to kidney function, and that concept is difficult for patients and even PCPs sometimes to follow,” he says. “What is good about the estimated GFR is it gives you a number for how well the kidneys are functioning.”
For example, an estimated GFR less than 60 suggests that a patient has developed CKD. It’s a simple concept for both providers and patients to grasp, so in an effort to get physicians to use this more precise measure, many experts and educational groups, including the National Institute of Health’s Kidney Disease Education Program, encourage laboratories to automatically report the estimated GFR as well as the normal and abnormal ranges that apply to the number whenever a physician orders a serum creatinine level.
An estimated GFR value not only gives the physician important information about a patient’s likelihood of progressing to the point where he or she needs dialysis or transplantation, it also provides critical insight on other aspects of care.
“At lower levels of kidney function, you have higher rates of CVD,” says Vassalotti.
Additionally, lower levels of kidney function can alter drug metabolism, potentially affecting all of the drug therapies that a patient receives—not just therapies for kidney disease.
CKD multiples CVD risk
A second calculation that is important to both PCPs and nephrologists is the urine albumin-to-creatinine ratio. “Abnormal levels of albumin in the urine or albuminuria represent not only kidney damage, but also probably vascular damage as well,” says Vassalotti.
“If endothelial cells—the cells that line the blood vessels—are damaged in the kidneys, then they are often damaged in other parts of the body such as the heart and the blood vessels that feed the heart, putting the patient at increased risk for heart attack, stroke, or HF,” he says.
Because of the strong connection that is observed between CKD and CVD, both the National Kidney Foundation and the American Heart Association have published position papers that recommend that patients with CVD undergo the test of kidney function—the estimated GFR—and the test of kidney damage—the urine albumin to creatinine ratio.2
“One of the messages that we are trying to deliver to the PCP is that CVD is the number one killer in Americans, and CKD multiples the CVD risk,” says Vassalotti. “The lower level of kidney function that a patient has, the more likely he or she is to die of a CVD event, and the more likely he or she is to be hospitalized.”3
PCPs miss signs of CKD
In addition to relying on less accurate measures of kidney function, there is also evidence that some PCPs fail to recognize some signs and symptoms of CKD, and they may also be reluctant to refer patients on to a nephrologist.4 In a national study that asked 304 physicians to evaluate the medical files of mock patients that contained strong clues of CKD, 97% of the nephrologists surveyed accurately diagnosed CKD, but only 59% of the family physicians and 78% of the internists surveyed fully recognized the signs and symptoms of CKD.
“In our scenarios, patients were just crossing over into an estimated GFR of 30 over a fairly rapid time period,” explains L. Ebony Boulware, MD, the lead author of the study and an assistant professor of medicine at Johns Hopkins University School of Medicine in Baltimore. Boulware adds that this is the point where guidelines issued by the National Kidney Foundation suggest that patients should be referred to a nephrologist.
However, one point that Boulware and her coauthors make in the study is that PCPs are often not aware of the guidelines regarding CKD. “There is very little dissemination of these guidelines to PCPs, and so there is very little consensus among the medical specialists regarding when patients should be referred,” she says.
“When we present these data to generalist physicians, they believe the situation is more complex, which is true,” she says. “Not every patient necessarily needs to be referred [to a nephrologist] if, in fact, the patient is receiving appropriate care.”
To establish more of a consensus regarding referral practices, Boulware would like to see collaborative guidelines developed, including both nephrologists and generalist physicians. She believes this would not only provide more visibility of the recommendations to PCPs, but also take into account their views and experience.
New care models are needed
Along similar lines, both Vassalotti and Boulware agree that care models need to be developed that facilitate the care of patients with CKD by both nephrologists and PCPs.
Such models might include opportunities for PCPs to consult with nephrologists, particularly in the earlier stages of CKD, and then as the disease progresses, to jointly care for the patient.
“There are an estimated 20 million people in the United States with CKD, and it is just not feasible for the several thousand nephrologists to see all of those patients,” says Vassalotti.
One of the hurdles to overcome in engaging generalist physicians more in the care of CKD patients is the negative perception that many of them have about the disease, says Vassalotti, noting that there are numerous alternatives for early treatment.
“We need to make it a positive message for PCPs,” he says. “If they diagnose CKD, they can produce better outcomes for their patients. That is what we really need to emphasize.”
1 Anavekar N, McMurray J, Velazquez E, et al. Relation between Renal Dysfunction and Cardiovascular Outcomes after Myocardial Infarction. NEJM 2004; 351:1285–95.
2 Brosius III F, Hostetter T, Kelepouris E, et al. Detection of Chronic Kidney Disease in Patients With or at Increased Risk of Cardiovascular Disease. Circulation 2006; 114.
3 Go A, Chertow G, Fan D, et al. Chronic Kidney Disease and the Risks of Death, Cardiovascular Events, and Hospitalization. NEJM 2004;351:1296–1305.
4 Boulware LE, Troll M, Jaar B, et al. Identification and Referral of Patients with Progressive CKD: A National Study. American Journal of Kidney Diseases 2006; 48:192–204.
Screening program shifts gears to focus more intently on CKD-CVD links
The National Kidney Foundation has screened Americans at risk for chronic kidney disease (CKD) for the past 10 years through its Kidney Early Evaluation Program (KEEP). Data from these screenings suggest there is a large number of undiagnosed people whose lives could be prolonged with appropriate diagnosis and care.
Nearly one-third of all individuals who have undergone KEEP screening have been found to have CKD, but only 2% knew they were at risk prior to attending the screening. Additionally, more than 30% of KEEP participants have diabetes, 69% have elevated blood pressure, and nearly 86% have at least one CVD risk factor.
In light of these findings, the National Kidney Foundation intends to ramp up the KEEP effort with the development of new screening strategies and a broader focus on the links between CKD and CVD. The organization reports that death from CVD is 10–30 times higher in people with advanced CKD than the general population. However, research shows that CVD complications and progression of CKD can both be modified through early intervention.
The foundation has appointed a new, multidisciplinary KEEP steering committee with combined expertise in nephrology and cardiology to underscore the significant links between the two diseases. Further, they hope to leverage the general knowledge of CVD risk among patients to drive awareness of CKD.
Editor’s note: More information about KEEP, including a schedule of planned screening events, is available at www.keeponline.org.