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Who and how should we screen for chronic kidney disease
in the elderly population?
R.T. Gansevoort
University Medical Center Groningen, The Netherlands
MAY 11th - MINI LECTURE 9 - HALL K11 14:30 - 16:00
Recently a classification system has been designed to characterise the various stages of chronic kidney disease. This classification system was set up to facilitate identification of subjects at high renal and cardiovascular risk, who may benefit from timely start of preventive treatment. This classification system is endorsed by the international societies for kidney disease, has been widely accepted by the medical community and led to wide-spread acknowledgement of the importance of renal function impairment. Of note, in this classification system fixed cut-off values for renal function are used to define the various stages of chronic kidney disease. When these cut-off values are applied approximately 10% of the general population appears to have CKD. Especially stage 3 CKD, defined as a renal function between 60 and 30 millilitres per minute, is very prevalent, with figures of 5 to 6%.
Importantly, renal function declines during aging, even in completely healthy subjects. Because of the natural decline in renal function many elderly, especially women, have a renal function below 60 millilitres per minute. Consequently worldwide millions of elderly subjects are identified as suffering from CKD and to be at risk to develop end-stage renal disease and cardiovascular events. It is questionable whether this assumption is correct.
The last two years evidence is accumulating that in the elderly low renal function is less associated with a bad prognosis when compared to younger subjects. Most of the elderly subjects with “low” renal function have a prognosis with respect to renal and cardiovascular outcome similar to elderly subjects with “good” renal function. Only the subgroup of elderly subjects with “low” renal function AND additional signs of kidney damage, e.g. urinary protein loss, appear to be at risk for accelerated renal function decline and to develop myocardial and cerebrovascular infarctions. These recent findings are strong arguments to improve the present international classification system for chronic kidney disease.
In this respect there are two options. First, in future age and gender specific cut-off values could be used to define subjects as having chronic kidney disease. For instance subjects that are 80 years old will only be called having chronic kidney disease when their renal function is below 45 millilitres per minute. Second, fixed cut-off values could still be used in case the importance of additional signs of chronic kidney damage is emphasized. Elderly, but even younger subjects with a renal function between 60 and 30 millilitres per minute should only be called having chronic kidney disease in case they also have increased urinary protein loss. The public health implications of this debate are enormous. Both aforementioned options will prevent misclassification of millions of people worldwide as having chronic kidney disease and will help to identify subjects with true chronic kidney disease.
