Monday, April 21, 2014

The ongoing debate about the definition of CKD in the elderly

In NDT this month, there is a nice series of articles outlining the ongoing debate about whether or not an eGFR<60 should be considered a disease, particularly in the elderly. The pro side was argued by Giuseppe Conte and the anti by Richard Glassock. Finally, there was a moderator's opinion written by Stein Hallan and Ron Gansevoort.
Dr. Glassock makes the familiar argument that age-related decline in GFR is ubiquitous and should not be considered a disease (with the associated anxiety and insurance issues that accompany such a diagnosis). This is particularly the case in elderly patients with stage 3a CKD and no albuminuria who almost never progress to ESRD and, in fact, whose eGFR declines at a rate of approximately 1ml/min/year. Labeling these patients as "CKD" leads to a huge expansion in the number of individuals diagnosed with CKD over the age of 75 in particular encompassing a significant proportion of the US population who reach this age.

In this, he is countered by both the con side and the moderator who take the position that CKD 3a is something that should not be ignored and should not be considered a part of normal aging.The most convincing argument in favor of this position is the relative risk of death from cardiovascular disease in patients with moderate reductions in eGFR relative to those with preserved renal function. It is well known that CKD is associated with an increased risk of CVD. Although the relative risk of CVD decreases as individuals age, even in elderly patients, those with CKD stage 3a are approximately twice as likely to die of CVD than those without CKD. This risk is present whether or not individuals have proteinuria. As the moderator points out, in the 1970s, high blood pressure and high cholesterol were ignored in the elderly as they were seen as being a normal part of aging despite the fact that epidemiologic data suggested that these were associated with adverse outcomes in the elderly too (although, as with CKD, the relative risk was reduced compared to younger individuals). eGFR-defined CKD is an independent risk factor for cardiovascular disease. The fact that there is an absence of specific therapies that could be used in this population to slow decline or attenuate CVD risk (beyond traditional risk factor treatment) does not mean that it should be ignored. In fact, given the high prevalence of this condition in the general population, and the number of excess CVD deaths that can be attributed to CKD, this is an area where research should be focused to determine how we can reduce risk in these patients. I'm afraid I have to go with the moderator and Dr Conte on this one.

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