Chronic kidney disease (CKD) is likely to be the most common condition managed by practicing nephrologists in elderly patients attending a nephrology clinic. Why? Because the majority of individuals with renal disease are 65 or older (Figure 1) and CKD is the most common renal disease in the older individual.
Although it is a common condition, and each one of us is clearly able to manage CKD, many would argue that CKD should be considered a different disease for older individuals compared with younger people. The disorders and other causes for most cases of CKD are different in younger individuals, the health implications differ, and, at least in some respects, the appropriate treatment is age-sensitive.
Despite having a common final pathway, CKD in elderly individuals is more likely to result from chronic, asymptomatic conditions such as vascular disease, hypertension, obstructive uropathy, or repeated acute kidney injury than from inflammatory or systemic renal diseases. Consequently, the clinical presentation may differ, the management may be multidimensional, and the outcomes may be more dependent on comorbid illnesses.
At a population level, multiple studies have clearly shown that the presence of CKD is associated with increased mortality (in particular cardiac mortality), prolonged hospitalizations, and poorer long-term health outcomes (such as need for renal replacement therapy, myocardial infarction, strokes, etc,) across all age groups. However, a significant number of studies also emphasize that the relative increase in risk is considerably lower for elderly individuals than their younger counterparts. The implication is often that the presence of CKD is of lesser significance in older individuals than in younger individuals, but in fact, particularly when limited to those with a rapid decline in renal function (defined as those with a fall in eGFR of ≥ 3mL/min/yr), the increase in absolute risk of mortality is impressive.
The older individual is at higher baseline risk of one or more adverse health outcomes (death, ill-health, hospitalization) and so even small increases in relative risk result in dramatic increases in absolute risk. For example, a person of 40 years with an estimated glomerular filtration rate (eGFR) of 30–39 mL/min has an absolute increase in annual mortality of 2.2 percent compared to someone with normal renal function, while for the 75-year-old the absolute increase in mortality is almost double at 4.2 percent each year.
Screening and diagnosis of CKD is also more challenging in elderly populations. Isolated, or even multiple reports of low eGFR need to be interpreted in the context of a complete medical and, if possible, geriatric assessment. Comprehensive geriatric assessments (CGA) may help early recognition of frailty, muscle loss, and psychosocial factors, all of which may be associated with decreased muscle mass and overall well-being. Although time consuming, incorporation of periodic comprehensive geriatric assessments into routine CKD care also helps determine the most appropriate care path as CKD advances. A variety of widely available tools are available online for both physicians and other allied health staff (http://www.healthcare.uiowa.edu/igec/resources-educators-professionals/).
All equations that estimate renal function from measured serum creatinine values include age as a key modifying variable. The most commonly used, the abbreviated 4-item Modification of Diet in Renal Disease study (MDRD eGFR) equation, uses age as a surrogate for change in body composition.
The assumption (which works well at a population level) is that as one ages, one has a gradual fall in body muscle content. However at the individual level this relationship may not hold true. The age at which muscle loss starts, and the rate of loss, varies considerably between individuals. Nonmedical factors such as financial independence, access to food, and ability to prepare food, influence overall health.
Individuals who are fortunate and can maintain their health, independence, and exercise level, often have a slow, somewhat predictable decline in muscle mass with age. In these individuals the use of the MDRD formula will likely underestimate renal function. On the other hand, individuals who are dependent on caregivers to buy or prepare food, have cognitive issues, or medical conditions predisposing to frailty or prefrailty characteristics such as weight loss or reduced exercise tolerance are likely to have already experienced a significant degree of muscle loss at an early stage of life. These individuals are more likely to have ‘normal’ or low serum creatinine levels and therefore run the risk of unrecognized CKD.
Both overdiagnosis and underrecognition of CKD are of considerable concern. In the former situation, the simple act of labeling an otherwise healthy individual as one with CKD is likely to lead to unnecessary additional testing and follow-up, medications, and possibly impact quality of life. On the other hand, underrecognition of CKD may lead to errors in drug dosing and possible inappropriate prescribing of nonsteroidal drugs or radiological contrast. Although initial excitement over alternative creatinine-based formulae or measures such as cystatin C has waned, the search for the perfect “renal troponin” continues. Currently, the most optimal seems to be ongoing follow-p and evaluation for proteinuria, with eGFR estimation, and/or cystatin C measurement.
One of the most important clinical differences between elderly individuals and younger patients with CKD relates to treatment planning and therapeutic targets. The CGA is again a valuable tool in identifying possible detriments of the treatments traditionally used in CKD patients. CKD patients have higher levels of frailty, functional dependency and cognitive dysfunction and therefore are at higher risk of experiencing geriatric syndromes. Current blood pressure targets (≤130/80) offer little survival benefit for older patients and, particularly in those with reduced mobility or a tendency to fall, emphasis must be placed not only on the absolute sitting blood pressure but also on postural changes.
Recognition of the financial circumstances of an older patient may influence drug prescribing, while environmental assessments may influence dialysis modality choices and/or nursing strategies.
In the advanced stages of CKD, patients and families are often educated about different renal replacement strategies. The CGA is again a useful tool at this point. Documentation of changes over time, noted on sequential evaluations, may help families and patients appreciate subtle but significant changes in their nonrenal health and help during discussions about dialysis and nondialysis care strategies, dialysis withdrawal, and advanced planning.
Barriers to home dialysis may be recognized and overcome early in the dialysis planning period. Discussions around fistula creation may be guided by CGA evaluation findings. Current guidelines suggesting preemptive fistula creation in patients planning for hemodialysis do not differentiate between the 40-year-old and 80-year-old patient with stage 4/5 CKD. However, older patients are at higher than normal risk of fistula failure-to-mature; death prior to dialysis-need; and only have modest survival rates after dialysis initiation.
In the recently published ASN geriatric nephrology curriculum Seth Wright and John Danzinger discuss in detail the benefits, and risks, of fistula creation and advocate caution and careful consideration prior to referral for surgery. One option is to consider delaying fistula creation for three to six months while the older patient is established onto dialysis and adjusts to their new lifestyle.
The use of the CGA helps clinicians appreciate that the detection and management of CKD in elderly individuals requires ongoing collaboration with allied health and palliative care teams, geriatricians, as well as the family and patient. An appreciation of the impact that renal disease has on diet, lifestyle and well-being is necessary. To this point, it is humbling and insightful to take a few minutes to hear the patient’s perspective (http://www.youtube.com/watch?v=EOciMaCyJW4).
American Society of Nephrology Geriatric Nephrology Curriculum http://www.asn-online.org/education_and_meetings/geriatrics/ accessed 31 Dec 2010.
NephSAP 2011, volume 10 Geriatric Nephrology, January 2011.
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Anderson S, Halter JB, Hazzard WR, et al.. Prediction, progression, and outcomes of chronic kidney disease in older adults. J Am Soc Nephrol 2009; 20:1199–1209.
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