Assessing the Reliability and Accuracy of a Digital Ultrasonic Height Measurement Device for Children Aged Under Five Years in Melbourne, Australia

Accurate height measurement is essential for monitoring child growth. Our aim was to assess the reliability and accuracy of a handheld ultrasonic measurement device compared with a standard measurement board, with experts measuring 57 children aged 0-5 years in metropolitan Melbourne, Australia using a methods-comparison study design. The ultrasonic device demonstrated a similar reliability to the board with a technical error of measurement (TEM) of 0.23cm (95%CI: 0.21, 0.28cm) and 0.19cm (95%CI: 0.17, 0.22) respectively, both within current standards. F-test ratios (ultrasonic vs. board) for intra-measurer TEMs showed a close agreement for children ≤2 years at 1.39 (95% CI: 1.03, 1.87; p=0.03); and >2 years at 1.20 (95%CI: 0.94, 1.51; p=0.14). The ultrasonic device measured children slightly taller than the board (mean difference 0.19 cm; 95% CI: 0.09–0.29; SD=0.78; p<0.01), with a larger difference in older children who were measured standing (0.35 cm; p<0.01). The Bland Altman 95% limits of agreement ranged from -1.33cm to 1.73cm, demonstrating variance in the measurements between the different tools. Overall, we found that the ultrasonic device showed high reliability for children under 5 years when compared to the board, though accuracy was variable, with lower accuracy in taller children. Further testing is required to identify the source of inaccuracies and also evaluate reliability in other contexts.