December 3, 2013
The American College of Physicians (ACP) has published a clinical guideline that recommends against screening for chronic kidney disease (CKD) in asymptomatic adults without risk factors for CKD. This was a weak recommendation, based on low-quality evidence [1]. This recommendation was not accepted by the leadership of the American Society of Nephrology [2] who rather endorsed widespread testing for CKD to identify early disease.
The Medical Advisory Board was asked to evaluate these conflicting views and to prepare a position statement for consideration by the Board of Directors of the AAKP. The following represents a digest of the discussions held as a Conference Call and numerous e-mail exchanges:
Many patients identified as having CKD by currently available guidelines (e.g. KDIGO, 2013) [3] also have concomitant medical conditions such as diabetes, hypertension or known cardiovascular disease (CVD), [4] Some may also have a family history of kidney disease or have demographic characteristics that may predispose to CKD (such as African-Americans). Good clinical practice dictates that as many patients as possible from among the three groups should be assessed for the presence of CKD when they have encounters with physicians for medical care, using the tools of urinalysis and estimates of glomerular filtration (eGFR) calculated from serum creatinine values (or other suitable biomarkers). More effective population-wide screening of adults for hypertension, and screening of patients with type 2 diabetes for the presence of hypertension could effectively select a population of patients more likely to have CKD, and has been recommended by the U.S. Preventative Services Task Force [5, 6]. Whether genetic based risk of progression of CKD to ESRD will justify demographic-driven screening remains to be studied but screening of asymptomatic family members of patients receiving ESRD treatment might be appropriate and beneficial [7].
Many patients want to know their diagnosis and prognosis, want to make the effort to avoid or delay the development of any disease, and want to be able to plan for their future.
Education for those concerned about CKD and its complications is uniformly warranted. Emphasis should be on prevention or treatment of CVD, management of hypertension and diabetes, the control of metabolic acidosis, dietary and lifestyle modification, and avoiding nephrotoxic medications[8-13]. For most, the diagnosis of a chronic disease is highly unsettling, yet knowing one has CKD, so long as the diagnosis is valid and confirmed, may impart a greater willingness to modifications in life style and compliance so as to foster a delay in disease progression to ESRD or to avoid one or more complications of CKD.
Advocates of population-wide screening for CKD, argue that not to provide such screening will deprive those with early forms of CKD an opportunity to receive the standard of care already afforded patients with an establish diagnosis of CKD. However, evidence is lacking that such screening will reduce the burden of CKD and its complications, including ESRD, and may have negative consequences.
AAKP feels it is of utmost importance to clarify many of the concerns may have been raised among patients:
1. There are negative consequences of population screening.
The harmful consequences of CKD screening include misclassification of patients due to the inherent variability in assessing the serum creatinine and eGFR[14], questions regarding the diagnostic applicability of uniform absolute thresholds of eGFR or albuminuria across a broad array of gender and age, the adverse effects of unnecessary testing of “false positive” diagnosis of CKD (especially in the elderly), the psychological impact of being labeled as having a chronic disease, adverse events related to medications and the possible financial ramifications of the CKD diagnosis.
2. CKD is over diagnosed in the elderly.
Demystifying which CKD patients have a low risk for progression will come as a relief to elderly patients, who on routine testing have an mildly reduced eGFR (45-60ml/min/1.73m2) and little or no proteinuria often attributable to the natural decline in renal function with aging [15].
3. Many patients with CKD never progress to end stage disease.
Among the 313.9 million US Citizens, 13.1% meet current criteria for CKD [3]. There are 616,000 individuals receiving treatment for End Stage Kidney Disease, requiring either dialysis or a kidney transplant (0.2% of the total population of the US) [16]. They account for 6.3% of the 549 billion dollar Medicare budget. Lifestyle, adherence to diet and medications and avoidance of nephrotoxins are some of the determinants that influence progression. For some, genetic determinants might play a causal role in progression [17]. As we develop therapies specifically linked to these determinants, screening tools will be invaluable in selecting those with potential disease among populations with a genetic basis for ancestry-related disparities; but these tools are yet not ready for application on a population wide basis.
4. The stigma of being classified as having a chronic disease, post-uninephrectomy, might frighten away potential kidney donors.
A patient who donates a kidney may have a reduction in eGFR to below the threshold customarily used to define CKD, but such individuals do not have an excessive risk of ESRD or complications. Educational initiatives must stress that kidney donors, despite their laboratory values, tend to do very well and can lead a normal life.
5. Cardiovascular disease management in the presence of CKD is both necessary and challenging.
CKD is a risk factor for death from cardiovascular disease [18]. Many of the risks for atherosclerotic cardiovascular disease events can be adequately assessed by traditional risk scoring without reliance on eGFR or albuminuria. However, Stage 3 CKD patients are 19 times more likely to die from a cardiac event than reach dialysis [19]. Changing habits is difficult, and impacting cardiovascular endpoints can be disappointing in this population. A long-term randomized, controlled, multi-center, prospective trial specific to CKD that incorporates motivational interviewing has begun [20].
6. Patient education is important regardless of the category or stage of CKD.
An argument against the universal screening of the population for CKD is that scarce funds displaced for such screening and for the management of asymptomatic and risk-free patients could alternatively be used to educate entire populations on healthier lifestyles and the judicious use of over-the-counter medications. For instance, the use of NSAIDS is strongly discouraged in the elderly and cautioned in treated hypertensive patients, regardless of the presence of CKD [21, 22]. Theoretically, increasing educational initiatives could result in achieving the same intended beneficial consequence, but for a larger population base.
7. Misinterpretation of the ACP or ASN recommendations is feared.
There is great concern among the renal community that the ACP guideline will be construed as a signal not to check appropriate patients in their practices routinely for CKD, missing an opportunity to intervene and delay disease progression. Concerns are raised that patients with early markers of disease may not be identified until the disease has progressed beyond a point of treatment responsiveness. In addition, CKD patients may not be identified preoperatively, be placed on inappropriate doses of medications, or have iodinated contrast x-ray or gadolinium contrast MRI studies that could lead to adverse events.
But these concerns can be largely alleviated without the necessity of embarking on a program of universal screening.
Conclusions
The AAKP Medical Advisory Board cannot unequivocally recommend mass screening of asymptomatic adults for CKD at any age without medical or demographic risk factors or a positive family history due to the lack of evidence regarding benefits and harms.
Opportunistic identification of CKD and education about this diagnosis during encounters with a physician for medical care are appropriate, especially in those with risk factors such as a positive family history, diabetes, hypertension or CVD.
All testing for CKD should be accompanied by education concerning risk of misclassification, need for confirmatory tests and advice concerning life-style modifications, dietary changes and the potential benefits and risks of medical interventions.
An un-healthy diet or the excessive use of NSAIDs may worsen or aggravate complications of CKD. We recommend efforts to educate all persons at risk for CKD about the benefits of healthy living, controlling blood pressure, minimizing the risk of diabetes by maintenance of a normal body weight, managing elevated cholesterol levels and limiting salt and sugar sweetened beverages.
References