Discrimination Validity of the Modified Scoliosis Research Society outcomes Instrument (SRS-22) in Adults with Scoliosis

Introduction: The modified Scoliosis Research Society questionnaire (MSRS) has been proposed as an instrument for measurement of disease-specific health status in patients with scoliosis. The purpose of this study is to report the discrimination validity of the MSRS instrument in differentiating between adults with and without scoliosis, and to define the relationship between outcome domains and specific radiographic parameters of spinal deformity.

Material and Methods: Adults with scoliosis and age/gender matched controls were studies in an observational study. Discrimination validity of the MSRS was determined by comparing the means of responses in each domain between adults with scoliosis and a control group without scoliosis. Pearson correlation analysis was used to determine the relationship of each domain of the MSRS and SF-36 compared with radiographic process variables including sagittal balance, coronal balance, and major curve magnitude.

Results: 180 adults were included, 146 with scoliosis and 34 without. Average age was 47 (18-86) with 165 female and 15 male. Adults with scoliosis scored significantly lower on the MSRS and the SF-36 questionnaire in all domains, Pain (p=0.0001), Function (p=0.0001), Self-image (p=0.0001), and Mental Health (p=0.012). Pearson correlation analysis demonstrated no significant correlation between any radiographic process measure and any specific domain within the MSRS and SF-36 instruments (r<0.25).

Discussion: These results suggest that adult deformity has a significant and measurable impact on affected patients compared with controls. There is a poor correlation between radiographic parameters of deformity and outcome domains including pain, function, self-image, mental health and satisfaction with surgery. This finding suggests that no one process variable is most predictive of outcome using a self-assessment disease-specific instrument.