Reliability and Validity of the Swiss Spinal Stenosis Questionnaire for Iranian Patients with Lumbar Spinal Stenosis.

Background The purpose of this study was validation of the Persian translation of the Swiss Spinal Stenosis Questionnaire in order to be used by Iranian researchers. Methods A total of 104 patients with spinal stenosis diagnosis, who were candidates for operative treatment were entered into the study. The patients completed the translated questionnaire in the 1st and the 7th days of admission and 6 months after surgery. Visual analogue scale was used to determine the severity of the pain in the1st day and the 6th month. Discriminant validity, convergent validity, test-retest reliability, internal consistency, ability to detect changes and sensitivity to clinical changes were assessed for the statistical purposes. Results Cronbach's α was more than 0.9 for all the items. ICC was about 0.9 for all the items. For symptoms, physical and total items, Cronbach's α was 0.942, 0.957, 0.926 and Intraclass correlation were 0.891, 0.918, 0.862, respectively. Paired t-test was significantly different between the 1st day and the 6th month questionnaire. There was a positive correlation either between the first VAS and the 1st day questionnaire (1st day Q) (r=0.892, P=0.000) or between the 6th month VAS and 6th month Q (r=0.940, P=0.000). The Pearson's correlation between the difference of the total scores of the 1st day and the 6th month and satisfaction score after surgery showed negative correlation (r= -0.746, P=0.000). The effect size was 2.55. Conclusion The Iranian version of the Swiss Spinal Stenosis has excellent internal consistency, excellent reliability, good ability to alter with changes, especially parallel with clinical improvement, excellent ability to detect changes, and well either convergent or discriminant validity.Level of evidence: II.