Validation of Bedside Ultrasound to Predict Body Composition in Non- and Critically Ill Patients (USVALID)

Validation of Bedside Ultrasound to Predict Body Composition in Non- and Critically Ill Patients: The USVALID Prospective Study

The prospective study will include 200 patients and 50 critically ill patients, who had an abdominal computed tomography (CT) scan including the L3 level for any clinical reason. Ultrasound scans of the anterior thighs and forearms will be taken after the CT scan within 48 hours. Bioelectrical impedance analysis (BIA) will also be performed. In addition muscle strength, mobility, physical function and nutrition will be assessed. Primary outcome is the prediction of CT-based whole body muscle and fat volume and BIA-based fat and lean body mass from ultrasound-based muscle and fat thickness. Other secondary outcomes include the intra- and interrater reliability of the CT evaluation and ultrasound examination of muscle and fat mass. The relationship between clinical aspects (strength, mobility, physical function, nutrition) and whole body composition is another secondary outcome.

Body composition measurements comprise the ultrasound measurement of fat and muscle thickness of both upper arms and thighs, the bioelectrical impedance analysis (BIA), measurement of weight, handgrip strength, overall muscle strength (Medical Research Council scale) and questionnaires about physical activity, nutrition and fluid status.

Body composition measurements comprise the ultrasound measurement of fat and muscle thickness of both upper arms and thighs, the bioelectrical impedance analysis (BIA), measurement of weight, handgrip strength, overall muscle strength (Medical Research Council scale) and questionnaires about physical activity, nutrition and fluid status.

In a linear regression model, the dependent variable is CT-based whole body muscle volume. The independent variable is ultrasound-based muscle thickness. The prediction (r2) of CT-based muscle volume in the multiple linear regression model is the outcome.

In a linear regression model, the dependent variable is CT-based whole body fat volume. The independent variable is ultrasound-based fat thickness. The prediction (r2) of CT-based fat volume in the multiple linear regression model is the outcome.

In a linear regression model, the dependent variable is BIA-based whole body muscle volume. The independent variable is ultrasound-based muscle thickness. The prediction (r2) of BIA-based muscle volume in the multiple linear regression model is the outcome.

In a linear regression model, the dependent variable is BIA-based whole body fat volume. The independent variable is ultrasound-based fat thickness. The prediction (r2) of BIA-based fat volume in the multiple linear regression model is the outcome.

For intrarater reliability each of the 5 examiners repeats the ultrasound measurement in 12 patients. In a Bland Altman analysis, the mean difference (=bias) in muscle/fat thickness between repeated measurements of the same examiner is the outcome.

For interrater reliability each of the 10 different pairs of examiners analyzes 6 patients. For each pair both examiners perform the ultrasound examination. In a Bland Altman analysis, the mean difference (=bias) in ultrasound muscle/fat thickness between examiners is the outcome.

muscle strength in patients with different CT-based body compositions (sarcopenia, malnutrition, obesity, sarcopenic obesity)

Muscle strength is measured with MRC scale and hand dynamometry. The outcome is muscle strength evaluated in different patient's group according to their CT-based body composition. Sarcopenia is defined as lowered L3 skeletal muscle index. Malnutrition is defined at a BMI beneath18,5 kg/m². Obesity is defined as a BMI above or equal to 30 kg/m². Sarcopenia obesity is defined as lowered L3 skeletal muscle indices and a BMI above or equal to 30 kg/m2.

Inclusion Criteria: cross-sectional abdominal CT scan including the level of L3 vertebra for any clinical reason study-related ultrasound examination must take place within 48 hours of CT Exclusion Criteria: patients younger than 18 years

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