1 Department of Nephrology and Dialysis, Azienda Ospedale di Lecco Lecco, Italy 2 Department of Nephrology Hôpital Edouard Herriot Lyon, France 3 Division of Renal Medicine, Karolinska Institute, Stockholm, Sweden 4 Department of Nephrology and INSERM U507 Necker Hospital, Paris, France 5 Bone and Mineral Research Unit Hospital Central de Asturias, Oviedo, Spain 6 Division of Nephrology and Dialysis University of Vienna, Vienna, Austria 7 Department of Nephrology University of Heidelberg Heidelberg, Germany Email: nefrologia{at}ospedale.lecco.it
Sir,
We would like to thank Friedman for their comments on the European Consensus paper [1]. We found them interesting and agree with the authors that the issue of overweight has not been specifically addressed in our paper, mainly because by definition this is a European consensus and in the European dialysis population obesity is less frequent, at least at present, than in the US dialysis population. We agree that there is a growing threat of overweight and obesity; a problem associated with increased risk of sudden death, coronary artery disease, hypertension, diabetes and dyslipidaemia in the general population. More specifically, the new incident patients starting dialysis are progressively ageing and we know that in Western countries overweight is a growing problem in the normal ageing population. In addition, some specific and dramatically increasing causes of chronic renal insufficiency, such as diabetes, hypertensive nephropathies and, to a lesser extent, metabolic uric nephrolithiasis are positively related to overweight, suggesting a link that could not be simply a statistical association. In the conservative phase of chronic renal insufficiency, it is clear that for an overweight patient, mainly under one of the previous conditions, the right approach is an adequate management of obesity, taking into account, however, that weight loss is always a pathologic, even if desirable, condition. A quite different situation is the overweight patient with advanced renal failure starting dialysis. Unfortunately, dialysis is a condition that is still more likely associated with a progressive and irreversible weight loss during follow-up. This is the reason why we focused on malnutrition of dialysis patients in our consensus paper. Therefore, we stick to the position that in advanced renal failure, the potential benefit of not only acutely reducing obesity by weight reduction but also of a cautious reduction of overweight is far outweighed by the risk of excessive catabolism. As a matter of fact, some reports clearly underlined the beneficial relationship between overweight and survival [2,3], whereas low BMI was an independent predictor of increased mortality [4]. Thus, if there is a place for obesity management in the conservative phase of chronic renal insufficiency, this is not the case for terminal renal failure, as we had been clearly discussed to reach consensus with all of the authors of the consensus paper. Finally, to appropriately investigate the role of overweight in the dialysis population, it should be taken into account the key difference of the prognostic role of overweight at baseline and the prognostic role of the evolution of this state during follow-up. In other words, the key question is: is the reduction of overweight in dialysis patients as beneficial as expected for the population at large? This relevant information is unfortunately lacking and should be tested by well-designed, incident prospective randomized studies, setting up observation in patients at start of dialysis, without referring to a mix of prevalent and (new) incident patients. This would be in line with the comments by Friedman, in that it would allow the Nephrology community to approach the issue of overweight and obesity in the dialysis population adequately. Unfortunately, considering that this population is getting increasingly older, the problems of malnutrition, inflammation and atherosclerosis (also called MIA syndrome) are for sure the most important issues to deal with.
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