Diabetes mellitus as a cause of end-stage renal disease in Europe: signs of improvement

The ERA-EDTA Registry is an international collaboration collecting data on renal replacement therapy (RRT) in Europe and countries bordering the Mediterranean Sea via national and international registries. The data are used for focused scientific studies on specific questions and for epidemiological surveillance of the state of RRT in Europe, which is evaluated annually and presented in the traditional ERA-EDTA Registry Reports. In this issue of the Clinical Kidney Journal, Kramer et al. [1] provide a summary of the 2013 ERA-EDTA Registry Annual Report. At present, the ERA-EDTA Registry covers 49 registries in 34 countries. Almost two-thirds of these registries offer individual patient data. The summary focused on diabetes mellitus (DM) as a cause of end-stage renal disease (ESRD) requiring RRT. Diabetes is an important health concern. The estimated prevalence rate of diabetes in Europewas 8.5% in 2013 and is projected to increase to 10.3% in 2035 [2] (Figure 1). It is one of the main underlying causes of death in adults, accounting for ∼10% of all deaths in Europe [3]. Furthermore, persons who have diabetes in addition to chronic kidney disease have an ∼50% higher risk of ESRD and death than those at a similar level of estimated glomerular filtration rate [4]. Therefore, it is an important contributor to RRT in Europe. In total, 477 186 persons in Europe were receiving RRT in 2013. This amounts to an overall prevalence rate of 738 patients permillionpopulation in Europe and theMediterranean, and 17% of these patients had DMas the primary cause of kidney disease. The average incidence rate of RRT in 2013 was 122 persons per million population who started RRT in 2013 in the ERA-EDTA Registry area. About 24% of the incident RRT cases had DM as the primary cause of their kidney disease. One immediately notes themarked difference between the proportion of incident RRT cases due to DM and the proportion of prevalent RRT patients with DM. The authors report a markedly poorer 5year survival rate on RRT of 50.6% for patients who had DM as the primary kidney disease when compared with the overall 5year survival rate on RRT of 60.9%. Fortunately, evaluation of more recent short-term survival sends a more uplifting message: the overall 2-year survival rate on RRT has improved from 81.4% between 2004 and 2008 to 82.7% between 2007 and 2011. This improved survival rate was even more pronounced in patients who suffered from ESRD requiring RRT due to diabetes: from 77.3% between 2004 and 2008 to 79.4% between 2007 and 2011. Even more remarkably were the trends in incidence of RRT due to DM over the past decade. Despite a decreasing incidence of DM, its prevalence rate has steadily increased over the past few decades and is projected to increase even further in the two decades to come [2, 6]. Given the substantial proportion of patients with DMwho develop chronic kidney disease and ultimately ESRD, one would expect the incidence of RRT as a consequence of DM to increase as well. However, Kramer et al. [1] show that the incidence of RRT has remained stable over the past 10 years, even trending towards a slight decrease in recent years (see Figure 3 of their paper). They made a similar observation on data from the United States Renal Data System (USRDS). These resultsmean that the prevention of chronic kidney disease secondary to DM has improved, at least for Western countries. Still, the incidence of RRT secondary to DM was five times higher in the USA compared with Europe, whereas that of RRT due to other causes of kidney disease was two times higher. This may indicate that the progression of CKD to ESRD due to DM is far greater in the USA compared with Europe. One may speculate about underlying causes, which could include (i) differences in the management of ESRD, (ii) differences in genetic background, particularly in African Americans and (iii) differences in the prevalence of risk factors for progressive kidney damage. A study by van de Luijtgaarden et al. [8] indicated that nephrologists in high RRT incidence countries were more likely