Assessment of reliability and validity of the adapted Persian version of the Spinal Appearance Questionnaire in adolescents with idiopathic scoliosis

Purpose This study investigates the reliability and validity of the adapted Persian version of the Spinal Appearance Questionnaire (P-SAQ). Methods The stages of cross-cultural adaptation were conducted according to an internationally accepted guidelines. Reliability of the P-SAQ was measured by evaluating internal consistency and test–retest reproducibility using Cronbach’s α and intraclass correlation coefficient (ICC). Validity of the P-SAQ was assessed by factor analysis, and convergent and known-groups validities. Convergent validity was assessed through participant response on the P-SAQ and the revised 22-item Persian version of the Scoliosis Research Society (SRS-22r) questionnaire. Known-groups validity was assessed by comparing the P-SAQ scores according to the patients curve magnitude and treatment type. Results A total of 106 patients with a diagnosis of adolescent idiopathic scoliosis (AIS) were included. The P-SAQ demonstrated an acceptable internal consistency with a Cronbach’s α of 0.77 (range 0.65–0.72). The test–retest reliability was excellent (range ICC 0.85–0.98). There was a correlation between the total score, average scores of the general, curve, rib prominence, kyphosis, and trunk shift subscales of the P-SAQ and subtotal and total scores of the SRS-22r, r = − 0.2 to − 0.4, p < 0.05. The P-SAQ discriminated between patients with differing Cobb angle magnitudes and treatment types ( p < 0.01). Factor analysis supported the use of the appearance and expectations items as separate scales for the P-SAQ. Conclusion The P-SAQ is a valid and reliable tool that could be utilized to evaluate the perception of appearance for Persian-speaking AIS patients with different curve magnitude and treatment strategies. Level of evidence Level I- diagnostic studies.