Putting the World in World Kidney Day
This year, March 8th is World Kidney Day but kidney care for the vast majority of the world’s population remains a distant dream. Over the last ten years, understanding of the epidemiology and consequences of chronic kidney disease (CKD – approximately 50% or less of normal kidney function) has dramatically increased in the developed world. Approximately 8-13% of Western populations have CKD and it is closely associated with hypertension, diabetes and cardiovascular disease. If kidney function continues to decline, people with CKD may develop end-stage kidney disease (ESKD) and, in the absence of dialysis treatment or kidney transplantation, death is inevitable. There is evidence that decline of kidney function can be slowed with optimal control of blood pressure, often using angiotensin-converting-enzyme-inhibitors, treatment of hyperlipidaemia, good diabetic control and modification of lifestyle factors such as smoking cessation and weight loss. In the UK and USA, the incidence of ESKD appears to have stabilised and may even be falling, perhaps providing early evidence that strategies to slow CKD progression can have major benefits on a population level.
Despite this progress in developed countries, research into the prevalence of CKD in low and middle income countries is extremely limited. It is likely that CKD is a substantial problem, particularly in sub-Saharan Africa (SSA). Risk factors for kidney disease including hypertension and diabetes are common in SSA and the association between hypertension and ESKD is greater among people of African ancestry than among people of other ethnicities. This may relate to recently discovered genetic variations associated with rapid progression of kidney disease which are more common in African-Americans than Europeans. In addition the burden of kidney diseases associated with chronic HIV infection and glomerulonephritis, often related to other chronic infectious diseases, is likely to be high.
Results of the limited screening studies for CKD in SSA are alarming. Up to one-third of people with renal risk factors may have CKD but only 12% of those with the condition are aware of it. Deaths attributed to kidney disease among hospital admissions are high but ESKD has frequently non-specific symptoms making it difficult to diagnose without blood tests so deaths among people not attending hospital are likely to be markedly underreported. Provision of specialised care is scarce with less than 1 trained nephrologist per million population for most of SSA.
Awareness and political will to tackle the huge burden of non-communicable diseases (NCDs) in low and middle income countries has gained traction recently. However, campaigning has largely focused on specific conditions: cancer, cardiovascular disease, chronic respiratory diseases, diabetes and mental health. Cardiovascular disease and diabetes are intertwined with CKD, so increased survival for these diseases without screening and treatment for associated kidney complications may perversely result in increased incidence of ESKD. Since widespread provision of dialysis for people with ESKD is an unachievable goal for most countries in SSA at present this could lead to avoidable tragedy on a massive scale.
Experience in the western world has shown that understanding prevalence and treating risk factors for kidney disease progression can reduce the proportion reaching ESKD. Measures to tackle CKD are part of the World Health Organisation ‘package of essential non-communicable disease interventions for primary health care in low-resource settings’ and international efforts to share the knowledge and experience of the developed world with kidney doctors in emerging countries, such as the International Society of Nephrology Global Outreach Research and Prevention Program are underway. We must ensure that measures to tackle the huge burden of illness caused by the five major NCDs in low and middle income countries are not offset by an increase in other diseases, but integrated care is developed at the outset. That would truly make it World Kidney Day.
Laurie Tomlinson is a Clinical Lecturer in Translational Medicine based at Addenbrooke’s Hospital, Cambridge and also at the London School of Hygiene and Tropical Medicine. She is interested in kidney medicine, health policy and non-communicable diseases among many other things. Follow her on twitter: @roxytonin