Association Between Interdialytic Weight Gain, Perception About Dry Weight, and Dietary and Fluid Behaviors Based on Body Mass Index Among Patients on Hemodialysis

This study aimed to identify dietary and fluid behaviors associated with relative interdialytic weight gain (RIDWG) (divided by the respective dry weight [DW]) by stratifying the patients according to body mass index (BMI).This was a cross-sectional, multicenter investigation. Between July 2016 and March 2017, data were collected from 4 Japanese dialysis centers in 3 cities. The patients (n = 577) were asked to reply to a self-completed questionnaire, including questions on perception about DW and dietary and fluid behaviors. The differences in perception about DW and dietary and fluid behaviors were compared between RIDWG nonadherence (average RIDWG ≥5％ a month) and adherence subgroups.The 360 participants were stratified into thin (20; 28.6%), normal low (≥20 and 22; 22.5%), normal high (≥22 and 25; 31.7%), and overweight (≥25; 17.2%) groups on the basis of BMI. In the thin and normal low BMI groups, the RIDWG nonadherent patients were more likely to identify their DW as "looking to increase." Although the difference was less prominent between the adherence subgroups in the thin BMI group, the RIDWG nonadherent patients in normal low BMI group seemed to generally take less care to intentionally regulate their behaviors as a representative of sodium-intake/fluid management. Although patients with a larger body size (overweight and normal high BMI groups) were not associated with this perception about DW, they were associated with some demographic characteristics; regarding the normal high BMI group, a higher proportion of RIDWG nonadherent patients worked full-time, and they more frequently reported an irregular eating pattern.Dietary and fluid behaviors associated with RIDWG differed according to the BMI group. Assessing more specific types of patient behaviors, focusing on the underlying factors associated with dietary and fluid behaviors, and taking BMI into consideration are required.