Diagnosis and prevalence of protein‐energy wasting and its association with mortality in Japanese haemodialysis patients
Of the various complications of maintenance dialysis patients, those involving nutritional status have been shown to be some of the most powerful predictors of outcomes.3 To date, various clinical, biochemical, and assorted parameters that may be indicative of malnourishment in patients with kidney disease, including dialysis patients, have been reported,8 and there have been several terms for malnourishment in these patients. To avoid conceptual errors and misinterpretation of data, an expert panel of the International Society of Renal Nutrition and Metabolism (ISRNM) recommended “protein‐energy wasting (PEW)” as a uniform nomenclature to express malnourishment in patients with kidney disease. PEW has been defined as a state of decreased body stores of protein and energy fuels (body protein and fat masses).15 Furthermore, to produce a more systematic and rational approach to both research and clinical management, the ISRNM panel recommended four main categories for the diagnosis of PEW: (i) serum chemistry, including albumin (Alb), transthyretin, and cholesterol; (ii) body mass, including body mass index (BMI), unintentional weight loss, and total body fat percentage; (iii) muscle mass, including muscle wasting, reduced arm muscle area (AMA) and creatinine appearance; and (iv) dietary intake, including unintentional low dietary protein intake (DPI) and unintentional low dietary energy intake (DEI). Thereafter, the panel proposed the diagnostic criteria for PEW based on the measures of each category; at least three out of the four categories must be satisfied for the diagnosis of kidney disease‐related PEW.
Moreover, the ISRNM recently presented a consensus statement on the aetiology, prevention, and treatment of PEW in chronic kidney disease patients, including dialysis patients.16 Therefore, the concept of PEW has been widely recognized and is becoming popular. Several studies that assessed the nutritional status of haemodialysis (HD) patients according to the categories and criteria recommended by ISRNM have been reported.18 However, not all of the reports have recognized the clinical usefulness of these criteria, especially patient outcome.
As an indicator of body mass among the four categories recommended by the ISRNM, a BMI of less than 23 kg/m2 was stated by the panel as a marker of PEW. However, the panel also recognizes that the threshold for the BMI criterion may need further adjustment, especially in some populations, such as those from Southeast Asia, in whom a low BMI may not necessarily indicate a pathology.15 Notably, the World Health Organization (WHO) recommended a BMI range between 18.5 kg/m2 and 25 kg/m2 as normal for the general population.22 Therefore, we assumed that a BMI of <18.5 kg/m2 was suitable as an indicator of body mass in the diagnostic criteria for PEW in Japanese patients.
The aim of this study was to demonstrate, in Japanese HD patients, whether revising the threshold of BMI in the diagnostic criteria of PEW proposed by the ISRNM is appropriate. We also aimed to investigate the frequency of PEW based on this nutritional assessment tool, and the association of PEW with mortality.