Test Weight Validation in Preterm Infants.

Objective: Accuracy in the assessment of feed intake is important for preterm infants at risk of growth failure. Clinical observation tools are unvalidated in this population, and test weight measurement may be inaccurate in preterm infants taking small feed volumes. Methods: Test weights were performed to assess agreement between weights using a standardized protocol and a feed of known weight in preterm infants (born at <35 weeks gestational age [GA]) during their transition to oral feeding. Reproducibility was assessed using two repeated measurements in each participant. Agreement between test weights and known feed weights was assessed, and minimal detectable change was calculated. Results: Thirty-eight preterm infants (GA 30 + 5 (28-33 + 1), birth weight 1574 g (+/- 671 g)) were recruited and had test weights performed at CGA 35 + 3 (± 10 days). Each infant was weighed twice before and twice after each measured feed, and a high degree of reproducibility was found for both the paired pre-feed weights, ICC = 0.99 [0.99-0.99] and the paired post-feed weights, ICC = 0.99 [0.99-0.99]. The mean absolute difference between test weight and feed weight was 1.7 g (±2.2). We calculated the minimum detectable change as 0.96 g, representing the magnitude of change below which there is more than 95% chance that no real change occurred. Conclusions: During the establishment of oral feeds, a standardized protocol at the bedside for repeated pre- and post-feed weights demonstrated a high degree of reproducibility. Based on our data, test weight measurements are appropriate for use in this preterm population during the establishment of oral feeds.