Intra and interobserver reliability of the anterior trunk flexion angle measurements by the Whistance method

Abstract

The purpose of this study was to evaluate intra and inter-rater reliability of the Whistance angle measurements through kinematic angular analysis. Two photographs of fifty subjects were registered: the first in standing position and the second performing trunk maximal anterior flexion. Two observers measured the trunk flexion angle. The intra and inter-rater reliability of the measurements made were analysed by two statistical analyses: intraclass correlation coefficient (ICC) and Bland & Altman’s. The mean Whistance angle measured by the first observer was 78.9º±11.4° and his testretest was x=78.9°±10.9°. The second evaluator obtained a mean of 79.5°±11.1°. The ICC for the intrarater was 0.94, with 95% CI [0.91;0.97] and for Bland and Altman, 0.04 with 95% CI [-0.99;1.07]. The inter-rater values were, respectively, 0.98 with 95% CI [0.97;0.99] and –0.62 95% CI [-1.09;- 0.14]. Both intra and inter-rater reliability thus was high for both statistical analyses. The present study showed high intra and inter-rater reliability for the Whistance method of measuring the trunk flexion angle.