INTEROBSERVER RELIABILITY AND INTRAOBSERVER REPRODUCIBILITY OF THE SYSTEM OF KING ET-AL. FOR THE CLASSIFICATION OF ADOLESCENT IDIOPATHIC SCOLIOSIS

The classification of adolescent idiopathic scoliosis with use of the system of King et al, has become,widely accepted since its introductio n. The purpose of the present study was to establish the interobserver reliability and intraobserver reproducibility of this classification system. The preoperative radiographs of sixty-three patients who were managed operatively for adolescent idiopathic scoliosis were classifie d by five observers with the system of King et al, Interobserver relia bility was assessed by comparison of the classification of the curves among the observers, and intraobserver reproducibility was evaluated b y comparison of the classifications of each set of radiographs by each observer on two occasions three weeks apart. The median interobserver reliability kappa coefficient for the classification system of King e t al, was 0.44 (range, 0.28 to 0,50), and the median intraobserver rep roducibility kappa coefficient was 0.64 (range, 0.44 to 0.72), Accordi ng to the definition of Landis and Koch, the classification system of King et al, is substantially reproducible but is only moderately relia ble. However, according to the stricter definition of Svanholm et al,, its reproducibility is only fair and its reliability is poor.