152 Chapter 7 Table 6. Ultrasound to estimate body composition in preterm infants Author, year, country Measurement method Reference method Study setting Results Quality assessment Subjects N° preterms Time of assessment Nagel, 2020, United States of America Ultrasound images of the biceps (brachii and brachialis), abdomen (rectus abdominis), and quadriceps (rectus femoris and vastus intermedius) using a portable B-mode US device ADP 63 preterm infants 63 (GA 32.0 + 2.2 weeks) PMA 35.1 + 1.2 weeks Biceps adipose tissue and total sum of adipose tissue thickness explained respectively 17% and 16% of fat mass percentage Level of evidence 2 Strengths & limitations Assessment of agreement with reference method – Assessment of intra- and interobserver variability + Repeated measurements + Coefficients of variance assessed + Sensitivity analysis + Bootstrapping analysis – Cross validation group – External validation – Large study population – Exclusively preterm infants + ADP: air displacement plethysmography; GA: gestational agePMA: postmenstrual age Large study population > 100 participants Levels of evidence based on the Oxford Centre for Evidence-based Medicine’s Levels of Evidence (15) Level 1: Validating cohort study with good reference standards*; or clinical decision rule tested within one clinical center. Level 2: Exploratory cohort study with good reference standards; clinical decision rule after derivation, or validated only on split-sample or databases Level 3: Non-consecutive study; or without consistently applied reference standards Level 4: Case-control study, poor or non-independent reference standard Level 5: Expert opinion without explicit critical appraisal, or based on physiology, bench research or “first principles”
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