Discriminative Properties of the Spinal Appearance Questionnaire Compared With the Scoliosis Research Society–22 Revised

Study DesignLongitudinal cohort.ObjectivesTo determine the responsiveness of the Spinal Appearance Questionnaire (SAQ) in patients with adolescent idiopathic scoliosis (AIS) undergoing surgical correction of the deformity.Summary of Background DataThe SAQ has been found to be a valid and reliable measure in patients with AIS. A recently published factor analysis and scoring system has been shown to be applicable to all Lenke types and had greater correlation to the curve magnitude than the Scoliosis Research Society (SRS) Appearance and Total score.MethodsFrom a prospective multicenter database, 126 AIS patients who underwent correction of the spinal deformity with complete SAQ and SRS-22 Revised data at baseline and 2-year follow-up were identified. Discriminative properties of the SAQ domains (Expectations, Appearance, and Total) and SRS domains (Appearance, Activity, Pain, Mental, Satisfaction, and Total) were compared by computing the effect size (ES) and the standardized response mean (SRM).ResultsThe SAQ Total had the largest ES (1.8) and SRM (1.5). This was followed by the SAQ Appearance, with an ES of 1.7 and SRM of 1.4; and the SAQ Expectations, with an ES of 1.5 and SRM of 1.2. Among the different SRS domains, only the Appearance (ES = 1.2, SRM = 1.1), Satisfaction (ES = 0.8, SRM = 0.6), and Total scores (ES = 0.8, SRM = 0.9) had effect sizes that were considered large. The SRS Mental domain had a moderate effect size (ES = 0.3, SRM = 0.3), whereas the Activity (ES = 0.0, SRM = 0.0) and Pain (ES = 0.2, SRM = 0.2) domains had small effect sizes.ConclusionsThe SAQ is sensitive and responsive to change, as evidenced by the large effect size for both domain and the Total score. The effect sizes are larger than those for any of the SRS domains, including Appearance and Total scores.