Comparison of Two Length Measurements: Lengthboard and Paper Barrier

Background: A calibrated lengthboard is recommended to measure length for children under 24 months of age. Physicians continue to use the disposable examination table paper and a non-stretchable tape to measure the distance between hand drawn lines to measure length. This study compares the intra-rater and inter-rater reliability and the differences between the two methods. Methods: A sample of 140 well children 2 weeks to 36 months of age was measured. Using standardized protocols and equipment recumbent length was measured twice each time by a pair of trained examiners using the lengthboard. Then, the length was measured using the paper method twice. Examiners were blind to their own and each other's measurements. Results: Study demonstrated high intra-rater and inter-rater measurement reliability for both methods. There was a statistically significant difference between measured length using the lengthboard and paper (p < .001), with a difference of up to 6 inches between two methods, and a mean difference of .65 inch using the Wilcoxin Signed Ranked Test. On the average, measurements were longer when the paper method was used. Conclusions: Study indicates that a high degree of reproducibility can be achieved using either method by trained staff. However, there is a very significant difference (p<. 001) of up to 6 inches between the two methods. This suggests that the recommended lengthboard is the more reliable method of measurement. Use of the paper method, especially in a busy practice setting can magnify errors and affect a child's percentile placement on the growth chart.