Reliability of three classification systems measuring active motion in brachial plexus birth palsy

Background: Several classification systems for the categorization of function in patients with brachial plexus birth palsy have been proposed. The purpose of this investigation was to determine the intraobserver and interobserver reliability of the modified Mallet Classification, Toronto Test Score, and Hospital for Sick Children Active Movement Scale in the evaluation of these patients. Methods: Eighty children with brachial plexus birth palsy were evaluated by two trained examiners on two different occasions. Intraobserver and interobserver reliability was determined with use of the kappa statistic. Results: On the basis of the kappa statistic, intraobserver reliability was good to excellent for individual elements of the modified Mallet Classification, Toronto Test Score, and Active Movement Scale in all age-groups. Interobserver reliability for individual elements of these three systems ranged from fair to excellent. When aggregate Toronto Test and modified Mallet scores were assessed, positive intraobserver and interobserver correlations were noted (Pearson r = 0.70 to 0.98, p < 0.001). Internal consistency (test-retest reliability) as determined by the Cronbach alpha for the aggregate Toronto Test and modified Mallet scores was excellent for each age-group (alpha > 0.90, p < 0.001). Conclusions: The modified Mallet Classification, Toronto Test Score, and Active Movement Scale are reliable instruments for assessing upper-extremity function in patients with brachial plexus birth palsy. The natural history and surgical outcomes of these patients can now be conducted with use of these reliable outcomes instruments.