Quadscan 4000

Body mass index (BMI), also known as the Quetelet Index, was calculated by dividing the measured body weight by the squared measured height (kg/m²). Participants were classified as: underweight (BMI < 18.5 kg/m²), normal weight (BMI 18.5–24.9 kg/m²), overweight (BMI 25–29.9 kg/m²), or obese (BMI ≥ 30 kg/m²). All circumferences (cm) were measured with a measuring tape in standing position: arm at the mid-upper left arm hanging loosely by the side, calf at the broadest point, waist at the smallest part between the lowest rib and the hip, and the hip at the broadest part [24 ]. Fat-free mass (FFM, kg) was estimated using multi-frequency bio-electrical impedance analysis (Bodystat Quadscan 4000) and the formula of Kyle [25 (link)]. The availability for body composition parameters ranged from 78% for FFM to 100% for BMI.

Lean body mass was measured using bioelectrical impedance analysis (BIA) (BodyStat Quadscan4000). It is appreciated that in vivo measurements cannot measure body composition directly, but rather make predictions from other physiological metrics. BIA was chosen because of its speed, simplicity, high precision and suitability for assessing short‐term changes in individuals (Johnson, Bolonchuk, & Lykken, 1985; Roubenoff, 1996; Wells & Fewtrell, 2006). In order to avoid the inherent problems of predicting total body water (TBW), regression equations for converting between impedance and TBW were avoided. Instead, the simple index of 1/impedance, which reliably predicts lean mass index (lean mass/height²), was used (Wells et al., 2007).

The collection of bio-clinical features including phenomics, biochemical variables and information on dietary and smoking habits has been reported [13 (link), 14 (link)]. Body weight, height, sagittal abdominal diameter and blood pressure (after 15 min rest) were measured. Body composition was measured by bioelectrical impedance analysis (QuadScan 4000, Bodystat Inc., Isle of Man, UK) and fat-free mass was calculated by subtracting fat mass from body weight. Intestinal transit time was assessed by abdominal X-ray after participants ingested nonabsorbable radio-opaque transit markers, and calculated based on the number of visible markers on the obtained abdominal X radiographs, adjusted for time since last marker ingestion [16 (link), 17 (link)]. Dietary intake of macronutrients was assessed from a validated four-day pre-coded dietary record [18 (link)]. Stool consistency was self-assessed according to a seven-point Bristol stool scale [19 (link)]. Smoking habits were categorized as current smoker or non-smoker.

At baseline, demographic and clinical data were collected for patients with IBD, including age, gender, physical activity, disease duration, weight, height, and measures of both fat and lean body mass. Anthropometric and body composition data were obtained during a morning examination while patients were in a fasting state. Body weight was measured using an electronic platform scale (Life Measurement Instruments, Concord, CA, USA), with patients wearing light clothing and no shoes. Body height was measured using a stadiometer (Sanny; American Medical do Brasil, São Paulo, Brazil), with patients standing barefoot, heels together, spine erect, and arms extended next to the body. Body mass index (BMI) was calculated as weight divided by height squared (kg/m²) and classified according to the World Health Organization (WHO) definition [33 ] as underweight (<18.5 kg/m²), normal weight (18.5–24.9 kg/m²), overweight (25–29.9 kg/m²), or obese (>30 kg/m²). Fat and lean body masses were measured using a bioelectric impedance device (QuadScan4000; Bodystat, Douglas, Isle of Man, British Isles), with the subject fasting, after urination and without jewelry or wristwatches beforehand. Patients with IBD were monitored for six months to evaluate routine clinical parameters and monitor for disease relapse.

Descriptive characteristics included the following: age, sex, BMI from measured weight and height (kg/m²), level of education, and living situation (with partner/children, alone). Level of education was assessed using the Verhage classification system [29 (link)] and categorized into low (scores 1–3), intermediate (scores 4 and 5), and high (scores 6 and 7). Fat-free mass (FFM, kg) was estimated using bio-electrical impedance analysis (Bodystat Quadscan 4000) and the formula of Kyle [30 (link)] and available of 195 participants. Furthermore, nutritional status was evaluated with the Mini Nutritional Assessment (MNA) [3 ]. To avoid that differences in MNA score were driven by differences in cognitive performance, we excluded the item on neuropsychological problems. MNA score range from 0 to 28 with a higher score indicating a better nutritional status and available of 163 participants.

The BMI was calculated as weight (kg) divided by height (m²) and classified according to the World Health Organization criteria [17 ]. Patients older than 60 years were classified according to BMI for the elderly according to Pan American Health Organization criteria [18 ].
The NRS 2002 is used to predict outcome based on risk parameters identified in the nutritional assessment. Patients are classified as at nutritional risk, when they obtain a sum of > 3 points. [19 (link)]
The validated Portuguese version of the scored PG-SGA was used to assess nutritional status. Subjective analysis classified the patients into three categories: (A) well-nourished, (B) moderately undernourished or suspected of being undernourished, and (C) severely undernourished. [20 ]
The phase angle (PA) was calculated as the ratio between resistance (R) and reactance (Xc) determined with QuadScan 4000 instrument (Bodystat Ltd., Isle of Man) which applies a 200 μA current at frequencies of 5, 50, 100, and 200 kHz. The PA for the whole body at 50 kHz was calculated from the impedance values using software supplied by Bodystat Ltd. All procedures and control for other variables affecting the validity, reproducibility and precision of the measurements were performed according to the National Institutes of Health guidelines. [21 ]