Validation of the Modified Scoliosis Research Society Outcomes Instrument (SRS-22) for Adult Deformity

Introduction: The modified scoliosis research society outcomes instrument has been validated as an outcomes tool for adolescent idiopathic scoliosis. There is not a validated disease-specific outcomes instrument for adult scoliosis. The purpose of this paper is to determine the reliability and validity of the modified Scoliosis Research Society questionnaire for adults with scoliosis.

Material and Methods: Reliability of the modified SRS instrument in adults was tested using Cronbach’s Alpha test of internal consistency, and calculation of test-retest parity. The validity of the modified SRS instrument in adults was determined by criterion validity in the domains of pain, function, self-image, and mental health compared with matched domains in the SF-36.

Results: 146 adults with scoliosis were included, 133 female and 13 male. The average age was 47.1 (range 18-86). Cronbach’s Alpha analysis of internal consistency within each domain demonstrates intercorrelation values ( ) >0.75 for each domain of the MSRS. Pearson correlation coefficients with comparable domains within the SF-36 demonstrate high correlation in domains representing pain (r=0.8), function (r=0.85), mental health (r=0.89), and self-image (r=0.63). Total score correlates highly with every domain of the SF-36 (r=0.6-0.8). Test-retest analysis in 36 patients who completed questionnaires at both timepoints demonstrated high correlations for each domain (r=0.83-0.94). A floor effect was seen in <2% of patients in each domain of the MSRS. A ceiling effect was seen in <10% of patients in each domain of the MSRS.

Discussion: Adult spinal deformity is significantly different than adolescent deformity in that affected patients characteristically present with pain and limitation of function. The MSRS questionnaire is a reliable instrument in adults, as demonstrated by a high degree of internal consistency and reproducibility. In adults with scoliosis, the MSRS questionnaire correlates highly with the SF-36 standard. The MSRS is a valid, reliable and reproducible outcomes instrument for adult deformity. This study supports the use of the MSRS questionnaire in the adult spinal deformity population.