Clinical efficacy and feasibility of whey protein isolates supplementation in malnourished peritoneal dialysis patients: A multicenter, parallel, open-label randomized controlled trial

Background and aims: Poor dietary intake is commonly associated with malnutrition in the dialysis population and oral nutritional supplementation is strategized to redress dietary inadequacy. Knowledge on clinical efficacy of whey protein supplementation (WPS) as an option to treat malnutrition in continuous ambulatory peritoneal dialysis (CAPD) patients is limited. Methods: This multicenter, parallel, open-label, randomized controlled trial investigated the clinical efficacy of WPS in 126 malnourished CAPD patients with serum albumin <40 g/L and body mass index (BMI) <24 kg/m(2). Patients randomized to the intervention group (IG, n = 65) received protein powder (27.4 g) for 6 months plus dietary counseling (DC) while the control group (CG, n = 61) received DC only. Anthropometry, biochemistry, malnutrition-inflammation-score (MIS), dietary intake inclusive of dialysate calories, handgrip strength (HGS) and quality of life (QOL) were assessed at baseline and 6 months. Clinical outcomes were assessed by effect size (Cohen's d) comparisons within and between groups. Results: Seventy-four patients (n = 37 per group) completed the study. Significantly more IG patients (59.5%) achieved dietary protein intake (DPI) adequacy of 1.2 g/kg per ideal body weight (p < 0.001) compared to CG (16.2%) although difference in the adequacy of dietary energy intake between groups was non-significant (p > 0.05). A higher DPI paralleled significant increases in serum urea (mean Delta: IG = +2.39 +/- 4.36 mmol/L, p = 0.002, d = 0.57 vs CG = -0.39 +/- 4.59 mmol/L, p > 0.05, d = 0.07) and normalized protein catabolic rate, nPCR (mean Delta: IG = +0.11 +/- 0.14 g/kg/day, p < 0.001, d = 0.63 vs CG = +0.001 +/- 0.17 g/kg/day, p > 0.05, d = 0.09) for IG compared to CG patients. Although not significant, comparison for changes in post-dialysis weight (mean Delta: +0.64 +/- 1.16 kg vs +0.02 +/- 1.36 kg, p = 0.076, d = 0.58) and mid-arm circumference (mean Delta: +0.29 +/- 0.93 cm vs -0.12 +/- 0.71 cm, p = 0.079, d = 0.24) indicated trends favoring IG vs CG. Other parameters remained unaffected by treatment comparisons. CG patients had a significant decline in QOL physical component (mean Delta = -6.62 +/- 16.63, p = 0.020, d = 0.47). Using changes in nPCR level as a marker of WPS intake within IG, 'positive responders' achieved significant improvement in weight, BMI, skinfold measures and serum urea (all p < 0.05), while such changes within 'negative responders' were non-significant (all p > 0.05). Conclusion: A single macronutrient approach with WPS in malnourished CAPD patients was shown to achieve DPI adequacy and improvements in weight, BMI, skin fold measures, serum urea and nPCR level. Clinical trial registry: www.clinicaltrials.gov (NCT03367000). (c) 2018 The Authors. Published by Elsevier Ltd on behalf of European Society for Clinical Nutrition and Metabolism. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).