Age, CKD and other kidney messages

Every March for the past 8 years, the International Society of Nephrology (ISN) and the International Federation of Kidney Foundations have jointly organised World Kidney Day (WKD; http://www.worldkidneyday.org). The purpose of WKD is to increase the awareness of kidney disease among politicians, the general public, general practitioners, physicians, nephrologists and other health care workers. WKD has been taken up with gusto in an increasing number of countries around the world, including Australia, and it is evident that the messages are being heard and to some extent have influenced policy. This year’s WKD will be held on 13 March, around the theme of “Chronic kidney disease (CKD) and aging”. Is this a message as substantive as those of previous WKDs?

Previous messages have been standouts. In 2007, the message was that kidney disease is common (affecting 10% of adults worldwide), harmful (not only from complications of CKD and end-stage kidney disease [ESKD], but also from a substantially increased risk of premature death, especially from cardiovascular causes) and treatable.1 In 2009 and 2010, the nexus between kidney disease and hypertension and diabetes, respectively, was stressed. Hypertension is a major risk factor for CKD and a key therapeutic target.2 The prediction that there will be 1.5 billion hypertensive people on our planet by 20252 is indeed a sobering one! Diabetes, especially type 2, is now the commonest cause of CKD and ESKD in most countries3 — and things are only going to get worse before they get better. By 2025, there will be almost 400 million people worldwide with type 2 diabetes3 and a similar number with impaired glucose tolerance, many of whom will go on to develop CKD. CKD, especially in the presence of proteinuria, is a principal risk factor for cardiovascular disease.4 Cardiovascular risk rises proportionally as kidney function declines; for example, Stage 3 CKD independently carries an almost 50% increased risk of cardiac death, a risk greater than that of diabetes or previous cardiovascular disease. Considering all stages of CKD together, there is a 100-fold greater chance of premature death (especially cardiovascular) than of developing ESKD. Importantly, interventions designed to slow CKD progression and reduce proteinuria appear also to reduce cardiovascular risk.

What began as a risky experiment about 50 years ago has now become routine practice in more than 80 countries around the world; there is no doubt at all that renal transplantation is the best way to replace kidney function in patients with ESKD.5 But, currently, only 10% of global need for kidney transplantation is met, restricted by economic considerations, insufficient donors, too small a trained workforce, immunological barriers and ethical considerations.5 Last year’s WKD focused on acute kidney failure (AKF). The prevalence of AKF is increasing worldwide and most cases are preventable,6 yet prevention and dialytic support during AKF are pipedreams for many countries. In response, the ISN has launched an ambitious program called “0 by 25” with the lofty aim that by 2025 no one should die of untreated AKF in the poorest parts of Africa, Asia and South America.

So is 2014’s WKD message as weighty as its antecedents (Box)? The latest message concerns CKD and ageing.7 Just like the body that surrounds them, kidneys age; a contemporary question is whether this ageing represents progressive CKD. Another key question is whether the automatic reporting of estimated glomerular filtration rate (eGFR) has spawned an epidemic of worried but well elderly people. The answer to the second question is yes and no. Otherwise healthy elderly people with a mild reduction in eGFR are likely to see out their years without any increased risk. However, whatever the cause of impaired eGFR, especially in the presence of proteinuria and with a rate of decline more rapid than expected for age alone, there will be increased risk.8 Despite their age, elderly patients with CKD will benefit from therapies aimed at slowing disease progression, better controlling metabolic derangements, reducing cardiovascular complications and allowing informed choices about ESKD therapy. That greater life expectancy does not necessarily equate with increased years of good health probably applies more to patients with CKD than any other ageing population. But treatment of selected older patients can increase survival, whether that treatment is conservative, dialytic or by transplantation. Older patients have less chance of undergoing transplantation, usually because of their comorbidities, but they can respond well, and various strategies (such as use of marginal and older donors) have increased the donor pool. Older patients with limited comorbidities can do well on dialysis, with improved survival; yet those with comorbidities may do better with non-dialytic, conservative therapy. So messages about CKD are just as important for older patients, and their wise application among older patients may do more for global health than among younger age groups.

What should developed countries be doing to lessen the global burden of kidney disease? Many developed countries must focus on their own groups at high risk of kidney disease, such as the Aboriginal population in Australia. In addition, they can play a key role in helping low-to-middle income countries tackle their kidney disease burden. The ISN directs a large proportion of its budget and efforts towards transformational capacity-building programs, including its Fellowship,9 Sister Renal Centre and other programs.10,11 By an increasing contribution to these programs, Australia can play a key role in the global response to kidney disease.