Further development and validation of the Scoliosis Research Society (SRS) outcomes instrument

Study Design. Outcome study to determine response distribution, internal consistency, and validity of a Modified SRS Outcomes Instrument (MSRSI). Objectives. Refinement and validation of the SRS Outcomes instrument for idiopathic scoliosis. Summary of Background Data. Experience with the SRS Outcomes instrument suggested several refinements and the need for validation. Methods. Following experience-based modification, the Modified SRS Outcomes Instrument and Short Form 36 (SF-36) questionnaires were administered to 35 previously surveyed postoperative idiopathic scoliosis patients. Results. Thirty (86%) patients with an average age of 25 years returned the questionnaires at an average of 10 years postoperative. Distribution of scores was acceptable. Internal consistency utilizing Cronbach's alpha was 0.80, 0.81, 0.77, 0.89, and 0.88 for pain, self-image/appearance, function/activity, mental health, and satisfaction with surgery, respectively. Validity, determined by Pearson correlation coefficients with comparable SF-36 domains, was 0.70 or greater for 13 of the 14 relevant domains between SF-36 and MSRSI (P < 0.001). Conclusion. The SRS Outcomes Instrument is simple and internally consistent. Based on experience, a number of modifications have been made that improve the instruments scope and internal consistency. Finally, the instrument is valid in comparison to SF-36.