Kidney disease label too broad

Too many people are being told they have kidney disease, experts claim today.

According to the latest in a series of articles on over-diagnosis, a new definition of chronic kidney disease labels more than one in 8 adults as having the disease.

Dr Ray Moynihan of Bond University, Australia, and colleagues write in today’s (31 July) British Medical Journal that "expanded definitions are unnecessarily labelling many people as diseased".

The United States Kidney Foundation launched a new framework for defining and classifying chronic kidney disease in 2002. It has since been widely used, but has also "generated considerable controversy", write the authors.

The 2002 framework defines "chronic kidney disease" as kidney damage or decreased kidney function for three months or longer, and uses the term to include conditions that may lead to loss of kidney function or complications caused by decreased kidney function. It relies on measures of glomerular filtration rate and various tests of kidney damage.

This framework was developed to create an agreed definition and classification, and with the aim of avoiding late presentation of serious kidney disease which can trigger other illness, particularly cardiovascular disease.

But the new definition labels about 14% of the population as having chronic kidney disease, say the authors. Previously, estimates of the rate were around 2%.

Given that rates of total kidney failure have not risen in line with the new definition, the authors believe that "many of those diagnosed will never progress to symptomatic forms of kidney disease", in fact, harm is done via the "psychological effect of a disease label and the burden and costs of repeated assessment, testing, and potentially unnecessary treatment".

Hence, doctors "should be sceptical about the current definition of chronic kidney disease and cautious about labelling patients".

Moynihan, R. et al. Analysis: Chronic kidney disease controversy: how expanding definitions are unnecessarily labelling many people as diseased. BMJ 31 July 2013 doi: 10.1136/bmj.f4298 [abstract]