A Scoping Review of Instruments Used to Measure Weight and Body Composition in Infants Under 1 Year

Background: This scoping review identified existing outcome measurement instruments (OMIs) for weight and body composition in children ≤ 1 year of age and how they are used in clinical trials. This information will improve outcome selection in future trials. Methods: We searched the EMBASE, MEDLINE, CINAHL, and PsycINFO up to September 2023, previous reviews, and the TOPCHILD collaboration registry. Screening was conducted independently in duplicate. We included studies reporting trials including healthy, full-term infants ≤ 1 year of age reporting at least one weight, weight gain, and/or body composition OMI. Study and OMI characteristics were synthesized narratively. Results: Seventy-two studies were included. Reported outcomes included weight (n = 71), changes in weight (n = 33), and body composition (n = 10). Six OMIs were used to measure infant weight, with undefined (n = 19) and electronic (n = 15) scales being the most common. Results for weight were mostly expressed as z scores relative to a population reference (n = 50). Five OMIs were used to assess infant weight gain, most frequently undefined weighing scales (n = 8) and electronic scales (n = 7), with results mostly expressed as changes in z scores relative to a population reference (n = 10). Eight body composition OMIs were identified; calipers (n = 5) and air displacement plethysmography (n = 3) were most commonly used. Body composition was predominantly presented as fat mass (FM) and fat-free mass (FFM) in kg (n = 5). OMIs were mostly administered in person by researchers, clinicians, or healthcare practitioners. Conclusions: Given the heterogeneity identified in this review, research is needed to select standardized, feasible, and reliable OMIs for infant anthropometric outcomes in trials.