BACKGROUND & AIMS: Sufficient protein intake is of great importance in hemodialysis (HD) patients, especially for maintaining muscle mass. Daily protein needs are generally estimated using bodyweight (BW), in which individual differences in body composition are not accounted for. As body protein mass is best represented by fat free mass (FFM), there is a rationale to apply FFM instead of BW. The agreement between both estimations is unclear. Therefore, the aim of this study is to compare protein needs based on either FFM or BW in HD patients.METHODS: Protein needs were estimated in 115 HD patients by three different equations; FFM, BW and BW adjusted for low or high BMI. FFM was measured by multi-frequency bioelectrical impedance spectroscopy and considered the reference method. Estimations of FFM x 1.5 g/kg and FFM x 1.9 g/kg were compared with (adjusted)BW x 1.2 and x 1.5, respectively. Differences were assessed with repeated measures ANOVA and Bland-Altman plots.RESULTS: Mean protein needs estimated by (adjusted)BW were higher compared to those based on FFM, across all BMI categories (P < 0.01) and most explicitly in obese patients. In females with BMI >30, protein needs were 69 ± 17.4 g/day higher based on BW and 45 ± 9.3 g/day higher based on BMI adjusted BW, compared to FFM. In males with BMI >30, protein needs were 51 ± 20.4 g/day and 23 ± 20.9 g/day higher compared to FFM, respectively.CONCLUSIONS: Our data show large differences and possible overestimations of protein needs when comparing BW to FFM. We emphasize the importance of more research and discussion on this topic.
Rationale: Malnutrition is a common problem in patients with Chronic Obstructive Pulmonary Disease (COPD). Whereas estimation of fat-free muscle mass index (FFMi) with bio-electrical impedance is often used, less is known about muscle thickness measured with ultrasound (US) as a parameter for malnutrition. Moreover, it has been suggested that in this population, loss of muscle mass is characterized by loss of the lower body muscles rather than of the upper body muscles.1 Therefore, we explored the association between FFMi, muscle thickness of the biceps brachii (BB) and the rectus femoris (RF), and malnutrition in patients with COPD. Methods: Patients were assessed at the start of a pulmonary rehabilitation program. Malnutrition was assessed with the Scored Patient-Generated Subjective Global Assessment (PG-SGA). Malnutrition was defined as PG-SGA Stage B or C. FFMi (kg/m²) was estimated with bio-electrical impedance analysis BIA 101® (Akern), using the Rutten equation. Muscle thickness (mm) of the BB and the RF was measured with the handheld BodyMetrix® device (Intelametrix). Univariate and multivariate logistic regression analyses were performed to analyse associations between FFMi and muscle thickness for BB and RF, and malnutrition. Multivariate analysis corrected for sex, age, and GOLD-stage. Odds ratios (OR) and 95% confidence intervals (CI) were presented. A p-level of <0.05 was considered significant. Results: In total, 27 COPD patients (age 64±8.1 years; female 60%, GOLD-stage 3, interquartile range=3-4, BMI 27±6.6 kg/m2) were included in the analyses. In the univariate analysis, FFMi (p=0.014; OR=0.70, 95%CI: -0.12—0.15), RF thickness (p=0.021; OR=0.79, 95%CI: -0.09—0.01), and BB thickness (p=0.006; OR=0.83, 95%CI: -0.06—0.01) were all significantly associated with malnutrition. In the multivariate analysis, FFMi (p=0.031; OR=0.59, 95%CI: -0.18—0.01) and BB thickness (p=0.017; OR=0.73, 95%CI:-0.09—0.01) were significantly associated with malnutrition. None of the co-variables were significantly associated with malnutrition. Conclusion: In this relatively small sample of patients with severe COPD, low FFMi and low BB muscle thickness were both robustly associated with increased odds of being malnourished. BB muscle thickness measured with US may provide added value to the toolbox for nutritional assessment. The results of this exploratory study suggest that upper body muscles may reflect nutritional status more closely than lower body muscles. Reference: 1 Shrikrishna D, Patel M, Tanner RJ, Seymour JM, Connolly BA, Puthucheary ZA, et al. Quadriceps wasting and physical inactivity in patients with COPD. Eur Respir J. 2012;40(5):1115–22.)
