Reliability of head circumference measurements in preterm infants

To describe and compare the intra- and interexaminer reliability of head circumference measurements obtained with paper and cloth tape measures.

Two experienced neonatal nurses each obtained head circumference measurements using both paper and cloth tape measures twice each, from 49 clinically stable, preterm infants. The nurses were blind to their own and to each other's measurements. The order in which the measurements were obtained was randomized. The differences within and between examiners for cloth and paper tape measurements were described using mean absolute differences, standard deviation of net differences, technical error of measurement, minimal and maximal differences, percentage of differences 0.25 and 0.5 cm, and percentage of error.

Wilcoxon matched-pairs, signed-ranks tests demonstrated significantly greater intraexaminer reliability for measurements obtained with the paper tape for both of the nurses. Wilcoxon matched-pairs, signed-ranks tests also demonstrated significantly greater interexaminer reliability for measurements obtained with the paper tape for both the first and second measurement sets.

Intra- and interexaminer differences were consistently smaller when the examiners used paper tape measures.