Development of the Simplified Chinese Version of the Spinal Appearance Questionnaire: cross-cultural adaptation and psychometric properties evaluation

Abstract

Study design: Cross-cultural adaptation and psychometric testing of the Spinal Appearance Questionnaire (SAQ).

Objective: To evaluate the reliability and validity of simplified Chinese version of the SAQ (SC-SAQ).

Summary of background data: The SAQ is widely used to assess the perception of spinal appearance in patients with adolescent idiopathic scoliosis (AIS). However, there is no culturally adapted, reliable, and validated SAQ for mainland China.

Method: The cross-cultural adaptation of the original SAQ was performed following international guidelines. The SC-SAQ was administered concurrently with the simplified Chinese version of the Scoliosis Research Society-22 (SC-SRS-22) questionnaire to 223 patients with AIS. A total of 92 patients were randomly selected to complete the questionnaires again 4 to 7 days after the first completion. Psychometric testing included reliability by internal consistency and test-test reliability, convergent validity by comparing the SC-SAQ with the SC-SRS-22 appearance domain, and discriminant validity by analyzing the relationship between SC-SAQ scores and patients' characteristics.

Result: Internal consistency for the SC-SAQ was satisfactory, with intradomain correlations ranging from r = 0.526 to r = 0.808 (P, 0.0001). The test-retest reliability for the SC-SAQ was excellent with intraclass correlation coefficient of 0.933 (95% confidence interval = 0.903-0.956) and good Bland-Altman agreement. (No systematic bias was found in the Bland-Altman plot.) Convergent validity test demonstrated a moderate correlation between the overall SC-SAQ and SC-SRS-22 appearance domain, with ρ = -0.401 (P, 0.0001). Correlation between the overall SC-SAQ and the major curve magnitude was significant, with r = 0.827 (P, 0.0001). Discriminant validity was confirmed by significant differences of overall SC-SAQ and individual domain scores among the 6 subgroups categorized by the major curve magnitude (P, 0.0001) and among patients requiring exercise, bracing, or surgery (P, 0.0001).

Conclusion: The SC-SAQ showed satisfactory reliability and validity in the evaluation of spinal deformity appearance for patients with AIS in mainland China.