The obesity paradox as it relates to survival and hypertension in dialysis patients

Abstract

Sir, Narkiewicz's [1] recent editorial on obesity and hypertension in the journal was timely and of interest. I have two comments and two questions. The study by Fleischmann et al. [2] and all subsequent studies have shown that obesity is only associated with better survival on haemodialysis, rather than causal to enhanced survival. This distinction is critical. The second comment is that the original and several subsequent works have demonstrated that obese patients tend to have better nutritional parameters [2,3], suggesting that better nutrition is probably the proximate mechanism for better survival rather than obesity per se. Indeed, Narkiewicz [1] is correct in pointing out that data so far does not support any better survival in obese patients on peritoneal dialysis. The curious question, therefore, has to be why. The answer may unlock the mystery-mechanism of obesity survival. Is it the high caloric intake imposed by peritoneal dialysis, and following the same line of thinking, can high caloric intake by lean patients on haemodialysis afford better survival? The second question, since there is a paradoxical association between obesity and survival in dialysis patients, is there any data to suggest that obesity is indeed associated with hypertension in patients on haemodialysis? Our study suggests that obese patients on haemodialysis may paradoxically have less severe hypertension than their lean counterparts [4].