A Public Health Action Plan Is Needed for Chronic Kidney Disease

Why is Chronic Kidney Disease (CKD) a Public Health Problem? 

A disease or condition becomes a public health problem when several criteria are met (Table 1).1, 2 First, it should impose a large societal burden that is growing larger, despite existing control efforts, and one that is expected to increase in the future. This burden is experienced in terms of mortality or morbidity, quality of life, and cost and is perceived as a serious threat by leaders in public health, by epidemiologists, by clinicians, and by the public, that is, there is a sense of fear that the disease is “out of control.” Second, the burden imposed by the disorder should be uneven; in many cases, this means that minorities and disadvantaged people are affected disproportionately. Third, there should be evidence that preventive strategies could substantially reduce the burden imposed by the condition. Finally, there should be evidence that such strategies are not yet in place. Here, we describe how chronic kidney disease (CKD) meets these criteria.

Table 1. Criteria for a Disease or Condition To Be a Public Health Problem.

	High disease burden
	Affects many people
	Has increased recently
	Is likely to increase in future
	Experienced in terms of mortality/morbidity, quality of life, and cost
	Perceived as a threat and out of control
	Uneven distribution: affects minorities and disadvantaged people disproportionately
	Evidence that prevention strategies could reduce burden
	Evidence that prevention strategies not yet in place

Data from1, 2

With regard to the first criterion, there are now more than 385,000 persons with end-stage renal disease (ESRD) in the U.S. Milder forms of CKD that do not yet require renal replacement therapy are even more common than ESRD. The total number of Americans living with CKD is now estimated to be 19.2 million, representing 11% of the adult US population, which dwarfs the 0.22% of the population with kidney failure.3 However, it is from this large pool of early CKD individuals that the ESRD population emanates.

The burden of CKD is growing, and this growth can be appreciated by examining the history of ESRD/kidney failure in the United States. During the past 3 decades, the incidence and prevalence of ESRD have risen progressively. For example, annual new cases of kidney failure increased from approximately 14,500 in 1978 to 100,500 in 2002, whereas the total number of persons living with kidney failure rose from 42,000 to 431,000, respectively.4 Over the 11-year period from 1990 to 2001, the national prevalence of ESRD rose 104%, an increase that occurred in all 50 states and the District of Columbia.5 Estimates for 1993 to 1995 were that 2% of white men, 1.7% of white women, 5.5% of black men, and 6.3% of black women would develop ESRD during their lifetime.6 Five years later, however, these estimates had increased (to 2.5%, 1.8%, 7.3%, and 7.8%, respectively).7 In terms of incidence, projections to the year 2010 show an annual increase of 4.1% in incident cases of ESRD,8 but recent data from the US Renal Data System indicate the rate of increase is lessening.4 By 2030, the estimated annual number of persons with new onset of kidney failure is expected to exceed 450,000, and those living with kidney failure are expected to number more than 2 million.9

CKD causes premature morbidity and mortality and reduces quality of life, but treating it is expensive. For those who have progressed to ESRD, yearly death rates approximate 20%.4 CKD patients have a risk of cardiovascular disease (CVD) that is 10 to 30 times that of people without kidney disease10, 11, 12, 13; indeed, the major cause of death in kidney patients is CVD, which is much more likely than progression to kidney failure.10 Deaths of patients with ESRD were estimated at 71,000 in 2000 and are expected to increase to 352,000 in 2030.9 Recently, using data from death certificates, the Centers for Disease Control and Prevention listed kidney disease as the ninth leading cause of death in the United States.14 However, this statistic probably underestimates the burden of kidney disease because CKD patients have a greater likelihood of dying from comorbidities of kidney disease than of progressing to ESRD. In addition to reducing the quantity of life, CKD reduces substantially the quality of life. Despite this large burden, CKD is often not recognized as a serious health problem in the United States.

Recently, data from a large, diverse population have shown that progressive decreases in the glomerular filtration rate (GFR) were associated with increased risks of death, cardiovascular events, and hospitalization.11 These risks were independent of known risk factors, a history of CVD, or the presence of documented proteinuria. In comparison with a GFR ≥60 mL/min/1.73 m2 of body surface area, the risk of death was 80% higher at an estimated GFR (in mL/min/1.73 m2) of 30 to 44 and nearly 600% higher with an estimated GFR <15.8 Against the same standard (≥60 mL/min/1.73 m2), the risks of any cardiovascular event and hospitalization were 2.0 and 1.5, respectively, at an estimated GFR of 30 to 44 and 3.4 and 3.1 at an estimated GFR of less than 15.8

Treating kidney failure imposes a large economic burden on patients, the health care system, and society. Although persons with kidney failure represent less than 1% of the Medicare population (those with kidney failure, regardless of age, are eligible for Medicare funding), their care consumes 6.7% of the health care expenditures by the Centers for Medicare and Medicaid Services. In 2002, total expenditures (Medicare plus private payers) exceeded $25 billion, of which approximately two thirds was provided by Medicare.4 Even so, the health care resources used in toto for CKD patients (without ESRD) actually exceed those used by the ESRD population; recent data from a large Health Maintenance Organization and from the United States Renal Data System indicate that the ratio is 1.6 to 2.4 (or higher) to 1.15, 16 The fact that now 1 in 9 Americans are estimated to have CKD and another 20 million are at risk for developing CKD has resulted in the sense of fear among some of the general public that the disease is “out of control.”

CKD clearly meets the second criterion for a public health problem (uneven distribution) because it disproportionately affects racial and ethnic minorities, among whom worse outcomes and higher costs of treatment are common. African Americans and Native Americans are at especially increased risk. Elsewhere, international data suggest that CKD is a worldwide public health problem.17 Age alone is a key predictor of CKD, and 11% of persons aged 65 years or over who do not have diabetes or hypertension have moderately to severely decreased kidney function.3 As for kidney failure specifically, diabetes is currently the most common cause, accounting for nearly one half of new cases of ESRD, and, by 2006, it is expected to surpass all other causes of new cases combined (hypertension, glomerulonephritis, others).9

The third and fourth criteria for classification as a public health problem (Table 1) are also met by CKD: preventive strategies could reduce its burden, and there is evidence that such strategies are not yet in place.17, 18 The burden that CKD imposes is tremendous, but there is good news—we have the requisite knowledge to prevent or at least delay the disease’s onset, progression, and comorbidities. “Upstream” preventive strategies are not yet in place, but, if implemented effectively, they could reduce the burden of CKD.

The Potential for Prevention Exists 

There are many reasons to believe that the burden of CKD can be reduced substantially. One key will be the early identification of those who are at risk; there is evidence that the disease can be detected in its early stages and that adverse outcomes can be prevented or delayed.17

Clinical diagnosis of CKD has become simplified. The most sensitive test for early CKD is urine albumin. At its earliest stage of low-grade albumin leakage, the term microalbuminuria is applied. Current recommendations call for testing annually in people with diabetes.17, 19, 20 The simplification in this approach has been the recognition that a spot or untimed urine collection with assay of albumin and creatinine concentrations allows their ratio to be calculated. This ratio can supplant the more cumbersome timed collection. Although urine testing for risk groups other than diabetes has not been so codified, testing for proteinuria, at least with simple dipstick methods, has been calculated to be cost effective in hypertensive people.21 Also, the GFR can be reasonably accurately estimated simply from the serum creatinine using an equation validated in a large number of subjects with CKD in combination with the variables of age, sex, and race.17 Thus, timed urine collections are now rarely needed to detect CKD; rather a single determination of serum creatinine and spot urine sample for an albumin to creatinine ratio suffices.

At present, preventive care practices18 include maintaining stringent blood pressure control to a target of 130/80 mm Hg, using angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers in both diabetic and nondiabetic nephropathies, maintaining careful glycemic control in those with diabetes, and following a low-protein diet.22, 23, 24, 25, 26, 27, 28 Treatment with ACEIs can be effective at all levels of kidney dysfunction, even if started late in the course of disease.29 Additional reports indicate that treating dyslipidemia,30 losing weight,31 quitting smoking,32 and managing anemia33, 34 may also help delay progression of early CKD.

The benefits of treating early kidney disease may extend beyond the kidney itself. Indeed, a recent publication indicated that in the general population the presence of albuminuria (a key indicator of kidney disease) predicted both cardiovascular and noncardiovascular mortality.35 In many cases, microalbuminuria is simply the renal manifestation of a generalized abnormality of vascular function.36 A recent report showed that treatment with fosinopril (an ACEI) of individuals who were identified from screening as having microalbuminuria led to a reduction in both albuminuria and in cardiovascular events,37 the latter being the major cause of death in patients with chronic kidney disease, as noted earlier.13

Several studies have shown the potential for preventing or delaying the initial onset of diabetic kidney disease18; this is often done by treating patients who have diabetes with ACEIs, which prevents the development of microalbuminuria (early diabetes-related kidney disease).38, 39 Early in diabetes, patients may have heightened kidney function, which manifests itself as glomerular hyperfiltration. Such a state may precede the development of microalbuminuria and the subsequent decline in GFR in diabetes.40, 41, 42

Unfortunately, at the present time, many patients with CKD still receive suboptimal care.43, 44, 45 The problem is both underdiagnosed and undertreated. The reasons for this are likely complex. Screening with quantitative urinary albumin measurements is underused in patients with diabetes. Also, the usual clinical index of kidney function, the serum creatinine concentration, is often poorly interpreted by clinicians. In addition, people at risk because of diabetes or hypertension are often unaware that CKD can be caused by these conditions.17, 46

A Public Health Approach for CKD 

CKD is not being detected early enough to initiate treatment regimens and reduce death and disability.46 In addition, many interventions are not being delivered early enough in the disease process to improve outcomes. Finally, most individuals with CKD are unaware that they have this disorder.17, 46, 47 Thus, the issue of CKD extends beyond a clinical problem, addressed only by health care providers, to a major public health issue requiring multilevel efforts. Initiatives should be undertaken to make health care providers, policy makers, and the general population more aware of the seriousness of CKD, its risk factors, and opportunities for early detection through screening. Persons identified with CKD should be provided appropriate educational materials to explain the treatment regimens and benefits of undertaking therapy. We must work with health care delivery organizations to ensure access to high-quality care at a population-based level, and we need data and information systems for health care policy makers to make informed decisions that will effectively address CKD.

The United States Renal Data System collects, analyzes, and distributes information on ESRD patients.4 However, at present, there is no data surveillance system for tracking patients with CKD in stages before dialysis or transplantation, unless they are 65 years or more and covered by Medicare (and thus can be tracked by the Centers for Medicare and Medicaid Services). The Centers for Disease Control and Prevention has national surveillance systems in place for many chronic diseases (eg, diabetes), but its data are scant for CKD. Clearly, to get a better understanding of the nature and extent of the CKD burden and to inform policy decisions, national surveillance data on this disorder need to be made available.

Additional public health efforts to address CKD are sorely needed, but some important first steps have already occurred. These have included publication of the NKF K/DOQI Clinical Practice Guidelines on Chronic Kidney Disease, a meeting of interested stakeholders to assess priorities48 and the establishment of the National Kidney Disease Education Program (NKDEP).49 Sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases, NKDEP was created to reduce the morbidity and mortality caused by kidney disease and its complications. Through public education and system-level initiatives such as the improvement in laboratory reporting of kidney function, the NKDEP aims to raise awareness that kidney disease is serious, that it is important to test those at risk, and that treatment is available to prevent or slow progression of the disease.49

Addressing CKD effectively will require multiple initiatives. A comprehensive effort will include not only patient and professional education but also the education of payers (Medicare, Medicaid, the health insurance industry) on the seriousness and costs of CKD and opportunities for prevention. In addition, the involvement or cooperation of business, members of the community, and government will be required; national, state, and local initiatives will all be needed. More surveillance and research efforts will be needed to measure and track the CKD burden, identify populations at risk, and to target program efforts.

Conclusion 

The burden of chronic CKD, as measured by human suffering and economic costs, is exploding as we move through the early years of the 21st century, making it a major public health problem. Currently, we have the tools to prevent or delay the onset of CKD and to limit its progression where it has already struck. Unfortunately, the extent to which we have applied these tools is suboptimal. A comprehensive public health approach will be needed to effectively address this major public health problem.