There are many triumphs to celebrate in nephrology. Over the last 10 years, we have been able to reduce the rate of first-year mortality for people beginning dialysis by more than 14%.1 The rate of rise in individuals initiating the treatment has slowed significantly, even starting to fall, and average survival once on dialysis is growing longer and longer.
One success we have not yet achieved, however, is getting all people with kidney disease to a nephrologist before they need dialysis, which would give them the chance to have their kidney disease progression slowed, to be educated about dialysis modalities, to have a dialysis access placed, and to be considered for preemptive transplantation.
Stages of Recognition
Only about 50% of people initiating dialysis saw a nephrologist within the year prior to the manifestation of a problem. In order to construct the solution to this issue, we need to appreciate what are the likely multiple factors behind our nationwide under recognition of kidney disease.
A pivotal study by Plantinga et al has contributed significantly to this endeavor.2 In the authors' analysis of the National Health and Nutrition Examination Survey (NHANES) data set, patient knowledge of the presence of their own kidney disease correlated with disease stage.
Less than 10% of patients with earlier stage kidney disease (Stages 1, 2, and 3) were aware of it. Among those with Stage 4 kidney disease, the percentage who knew they were operating with a glomerular filtration rate (GFR) between 15 and 30 rose, but only to approximately 40%. This proportion is unfortunately and eerily similar to the percentage of people who have seen a nephrologist within the year prior to initiating dialysis.
A National Kidney Foundation (NKF) study presented at the June American Diabetes Association Scientific Sessions in Philadelphia sought to further characterize why patient awareness of their own kidney disease is so limited.3 Each of the almost 10,000 patients enrolled in the study had serum creatinine measured for the calculation of estimated GFR and urine tests performed for the assessment of albuminuria or proteinuria.
Providers documented or acknowledged kidney disease as a medical problem in the records of only 12% of patients with the condition. When providers did recognize kidney disease in the medical record, they were effective in communicating this knowledge to their patients.
Unfortunately, like the patients in the NHANES study by Plantinga et al, provider recognition also varied with kidney disease stage, which was categorized according to the NKF Kidney Disease Outcomes Quality Initiative (KDOQI).4 The vast majority of early kidney disease was not documented, and only about half the cases of late-stage kidney disease were recognized.
Operating under the assumption that early identification can lead to early intervention, potentially prolonging kidney survival and delaying the initiation of dialysis, which in turn may lower cardiovascular mortality risk and even decrease the number of people requiring dialysis, a root cause analysis should be undertaken to understand the factors that contribute to this rather disturbing trend of under recognition:
* Are providers aware of the tests that can be utilized to screen for kidney disease?
* Do providers implement the screening tests in a regular manner?
* Do providers understand how to interpret these tests to characterize patients with early kidney disease (Stage 1)?
* Do providers know how to intervene to lower the risk that the screening tests indicate?
* And finally, do providers appreciate the chain of events that needs to take place to potentially lower cardiovascular risk in our patients?
Many or most of these questions still do not have answers. If we examine why kidney disease is not as well-known to the public as heart disease is, we quickly realize some of the complexities that make its early detection more difficult.
While coronary artery disease is indicated by chest pain, kidney disease is more often than not asymptomatic until its late stages, at which time the symptoms are vague and not necessarily specific to the kidneys.
The interventions that prolong renal survival, too, are not limited to the kidneys but are rather part of a cardiovascular risk-reduction regimen: increased attention to blood pressure control and blood sugar control, the use of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, and guidance about lifestyle changes, including a lower salt diet. Could the absence of interventions unique to kidney disease be a “public relations” issue that interferes with primary care providers more immediately seeing the utility of establishing which individuals have kidney disease?5
As we look at the markers used to identify kidney disease, arguably we will find that the laboratory tests fall short of the diagnostic specificity we see in other subspecialties. Cardiology has evolved from a dependence on the ECG for the detection of myocardial ischemia, to the use of less specific biomarkers such as lactate dehydrogenase (LDH), to the subsequent development of more specific biomarkers such as the myocardial fraction of creatinine phosphokinase (CPK) and then the various troponin assays.
In nephrology, the cornerstones for kidney disease detection continue to include the assessment of serum creatinine level and the examination of urine. Is there also a public relations issue here? Given that we have not identified in recent decades markers that more accurately reflect the presence of kidney disease, could it be perceived that these “old-time” biomarkers are too low-tech to work?
Another factor potentially contributing to the under recognition of kidney disease is that these “ancient” biomarkers are complicated to interpret. While they do predict which patients are at highest risk for progression to dialysis or to loss of kidney function, they also are associated with mortality risk. It is noteworthy that a slight increase in creatinine or urine protein excretion predicts mortality risk as well and possibly even better than laboratory parameters such as low-density lipoprotein (LDL) cholesterol do.6
Perhaps this is another issue of presentation—i.e. public relations. Rather than discussing the downsides of using these tests to predict kidney disease progression, maybe we should “market” these tests as inexpensive, noninvasive, and powerful measures of vascular health.
Now may be the time to educate the rest of the medical community that just as the kidney is the most oxygen-sensitive organ in the body, it can also provide a tremendous and powerful marker of cardiovascular risk.
The importance of understanding the utility of kidney disease screening and refocusing its purpose is highlighted by the recent US Preventive Services Task Force statement on the topic, which concludes that there are no data to support screening for kidney disease in the asymptomatic adult, highlighting many of the critical gaps in our knowledge.7
One of these gaps is the issue of the competing risks of mortality and progression to kidney disease. Another is the fluctuation in values of these “old-school” biomarkers and the need to interpret them carefully.
Given that awareness is so low, it is not surprising that the scientific link between screening and better outcomes has not been made. It could be considered somewhat of a vicious cycle: this task force recognizes the lack of data, does not support screening based on this lack of data, and may thereby be perpetuating the problem of unrecognized progression to late-stage kidney disease.
As America ages, as the proportion of its inhabitants with comorbidities such as diabetes and hypertension rises, and as our Medicare-eligible population grows with the increased access it is hoped health care reform will bring, we find ourselves at a critical juncture in history.
These conditions are a recipe for a chronic kidney disease and end-stage renal disease epidemic. “No evidence to support” does not mean we shouldn't screen or we shouldn't attempt to generate the evidence. We need to take advantage of every opportunity to have kidney disease recognized sooner. If we do, we may be able to prove that earlier therapy prevents or at least delays the progression to dialysis.
As we seek to reach a place of sustainable growth in health care costs, the time to critically examine our obstacles in the implementation of screening programs and early prevention is now. We can't let ourselves fall into the cliché of “you can't get a job without experience, but you can't get experience without a job.”
The future is low-tech. The future will require listening and a careful understanding of how to support our primary care colleagues in ways that we haven't in the past.
The future is about reframing the education given on the examination of urine. While it may be an important marker for the presence of potentially progressive kidney disease in many individuals, it is an important marker for the presence of vascular disease in many, many more. In terms of doing the greatest good for the greatest number, we need to refocus on simplicity.