Abstract
Objective: To compare multi surgeon reliability of the classification systems of H. A. King and R.W. Coonrad and to analyse controversial classified curve patterns.
Design: Three scoliosis surgeons and one orthopedic fellow were presented the AP radiographs of seventy adolescent idiopathic scoliosis patients. All reviewers assigned a type to each curve according to the classification systems of H. A. King [1] and R. W. Coonrad [2].
Subjects: Interobserver agreement and intraobserver reproducibility were tested. Kappa coefficients were used to test reliability. Between the observers, the divergent assignments to curve patterns were analysed in quantitative as well as in qualitative terms. An error analysis was performed.
Results: For King’s classification, paired comparisons revealed a mean interobserver kappa coefficient of 0.45, and for Coonrad’s classification system 0.38, respectively. According to Svanholm et al., these values indicate poor reliability in terms of interobserver agreement. Error analyses for both classification systems revealed that the reason for poor reproducibility is disagreement on structural upper thoracic and structural lumbar curves among the observers.
Conclusion: Neither King’s nor Coonrad’s method appear to have sufficient interobserver reliabilty. In order to improve reliability we recommend unequivocal description of structural stigmata of upper thoracic and lumbar curves.
The abstracts were prepared by Mr Peter Millner. Correspondence should be addressed to Peter Millner, Consultant Spinal Surgeon, Orthopaedic Surgery, Chancellor Wing, Ward 28 Office Suite, St James’ University Hospital, Beckett Street, Leeds LS9 7TF.
References:
1 King HA, Moe JH, Bradford DS, Winter RB. The selection of fusion levels in thoracic idiopathic scoliosis. J Bone Joint Surg1983, 65-A:1302–13. Google Scholar
2 Coonrad RW, Murell GA, Motley G, Lytle E, Lloyd AH. A logical coronal pattern classification of 2000 consecutive idiopathic scoliosis cases based on the Soliosis Research Society-defined apical vertebra. Spine1998, 23: 1380–91. Google Scholar
