Interobserver reliability of the Mallet score.

The interobserver reliability of the Mallet score for active shoulder function was assessed by three experienced observers in a group of 30 children with an obstetric brachial plexus lesion (mean age 7.1 years, range 4.5-10 years). Interobserver reliability, measured using weighted kappa, was good. Kappa varied between 0.37 and 0.84 and differed between the different aspects of the Mallet score and different pairs of observers. In decreasing order, mean weighted kappa was 0.75 for abduction, 0.73 for hand to neck, 0.67 for hand to spine, 0.6 for external rotation and 0.53 for hand to mouth.