In contrast, there was a direct relationship between the incidence of hypertensive nephropathy and the incidence of other nephropathies needing RRT ( Figure 2B). Indeed, there was an inverse relationship!! Thus countries with a higher percentage of the population with elevated blood pressure according to the WHO or higher systolic blood pressure (SBP) summary exposure values according to the GBD had a lower impact of hypertensive nephropathy on RRT ( Figure 2A). However, when plotting burden of hypertension, as estimated by the World Health Organization (WHO) or the Global Burden of Disease (GBD) Study against hypertensive nephropathy as a cause of RRT in the USA and Europe, no positive relationship is found. If indeed, hypertension was such an aetiological contributor to CKD requiring RRT, we would expect a relationship between the burden of hypertension in different countries and the contribution of hypertensive nephropathy to RRT in the same country. THE CONTRIBUTION OF HYPERTENSIVE NEPHROPATHY TO RRT IS NOT RELATED TO THE BURDEN OF HYPERTENSION The fact that we can escape so easily from recognizing that we do not know what caused CKD in the patient sitting in front of us will contribute to delay progress in aetiological diagnosis and personalized medicine in nephrology. This means that a diagnosis of hypertensive nephropathy essentially means CKD of unknown origin in a patient with hypertension, thus potentially relegating a diagnosis of CKD of unknown origin to the scarce CKD patients that do not have hypertension. Additionally, since the two key diagnostic requirements are hypertension and chronic kidney disease (CKD) and >80% of CKD patients develop hypertension, CKD patients with hypertension will fulfil diagnostic criteria for hypertensive nephropathy, especially when no diagnostic workup is made. This is contrary to the spirit of aetiological diagnosis. However, hypertensive nephrosclerosis remains a diagnosis of exclusion, which, in practical terms, means that the lower the quality of the aetiologic diagnostic workup, the higher the chances of being diagnosed as hypertensive nephrosclerosis. Hypertensive nephrosclerosis is also the second most frequent cause of RRT in the USA and the third in Japan ( Figure 1). In recent years, hypertension has been the second or third most common cause of renal replacement therapy (RRT) in Europe, tied with glomerulonephritis. This issue of Clinical Kidney Journal contains the summary of the 2017 Annual Report of the ERA-EDTA Registry. HYPERTENSIVE KIDNEY DISEASE AS THE SECOND MOST COMMON NEPHROPATHY REQUIRING RRT: CAN THIS STATEMENT BE MAINTAINED IN THE 21ST CENTURY? A diagnosis of nephropathy of unknown cause would be more honest when the full range of alternative aetiological diagnoses is not explored. Correct causality assessment and aetiology-based therapy is a key to the progress of nephrology and it should no longer be accepted that ‘hypertensive nephropathy’ serves to disguise a suboptimal diagnostic workup. There is an urgent need to redefine the concept of hypertensive nephropathy with a clear and comprehensive set of criteria that at least should indicate how other nephropathies, including familial nephropathies, should be excluded. It is not helpful that 80% of chronic kidney disease patients develop hypertension and kidney biopsy has no findings specific for hypertensive nephropathy. The current definition of hypertensive nephropathy is non-specific, outdated and only allows a delayed diagnosis by exclusion. In this regard, the incidence of RRT due to hypertensive nephropathy is related to the incidence of other causes of ESRD but not to the burden of hypertension per country. There is, however, one little issue: hypertension-induced end-stage renal disease (ESRD) might not exist at all as currently understood, that is, as hypertensive nephrosclerosis. In the 2017 Annual Report of the ERA-EDTA Registry, hypertension continues to be the second or third most common cause of renal replacement therapy (RRT) in Europe, tied with glomerulonephritis.
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