Likelihood-Evidential Support and Bayesian Analysis on a Prospective Cohort of Children and Adolescents with Mild Scoliosis Under Chiropractic Management

A previous study using frequentist analytic methods on a single cohort showed no difference in forty-one patients under chiropractic management for mild or early stage scoliosis. The grantor requested a re-analysis. Plain film radiographs of 41 children and adolescents were re-measured by Risser-Ferguson and Cobb methods. Three magnitudes and three types of change were constructed to cover various notions of scoliosis change: magnitudes of 1°, 3°, or 5°, and types that alternatively included or omitted no change as a possible successful outcome (arrested progression). Improvement was assessed from using three filters across three definitions of progression: 1) curve improved or stable, 2) improved only, and 3) those that either improved or progressed. Data were then analyzed by evidential support methods and Bayesian analyses at each filter and type of progression to establish whether improvement was likely attributable to treatment or spine characteristics.Intra-class correlation for intra-examiner stability was 0.73 by Cobb method. Reliability between the new and the previous examiner was 0.59 for pre- and 0.69 for post-treatment Cobb angles. Reliability increased dramatically when end vertebrae were specified. Ratio of number improved to those progressed to was at least 2:1 for all three levels of filter: 1°, 3°, and 5°. Number of treatments or duration of care were not associated with improvement. However, the number of vertebral segments below the scoliosis curve apex — a measure of curve compression ûand bone age accounted for 49% of adjusted R² in Cobb angle changes. Initial Cobb angle as a clinical predictor was not supported. One treating chiropractor experienced a greater rate of improvement at the highest level of change (5°) in his patients. Results here could not be attributed to management, but could be from a type of scoliosis resolving spontaneously, or a subgroup of scoliosis cases that responded to chiropractic management or manipulation.