Measurement properties of the Spinal Appearance Questionnaire in adolescents with idiopathic scoliosis: a systematic review

Abstract Background Scoliosis is defined as a three-dimensional deformity of the spine characterized by lateral tilt and axial rotation of the vertebrae. Its magnitude in the frontal plane is identified by a Cobb angle greater than 10o. The aim of the study was to systematically examine the clinimetric properties of the Spinal Appearance Questionnaire (SAQ) in its cross-cultural adaptations in different languages. Methods Medline (PubMed), CINAHL, EMBASE, Science Direct, PsycINFO and WorldWideScience.org databases were used for screening studies until July 16, 2022. In this study, records on the development, evaluation and translation of the SAQ instrument in adolescents with idiopathic scoliosis were included. In addition, two independent reviewers defined whether the studies were eligible and analyzed their psychometric properties of internal consistency, reliability, content validity, cross-cultural validity, construct validity and structural validity, according to the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN). The modified GRADE was applied for evidence synthesis. Results A total of 95 articles were selected by title and abstract. After removing duplicates and reading and searching the references, a total of 13 studies were included in this review. The original version of the SAQ was described in English, and the instrument was translated into Polish, Canadian French, Simplified Chinese, Spanish (Europe), Danish, Traditional Chinese, Portuguese (Brazil), Korean, German, Turkish and Persian. The evidence was moderate for construct validity, low for internal consistency, and very low for reliability and cross-cultural validity; the content and structural validity properties did not present minimum data for classification. Conclusion The quality of the evidence regarding the clinimetric properties of the SAQ instrument in adolescents with idiopathic scoliosis was low due to the absence of clinimetric properties or dubious methodological quality. However, for clinical practice and research, we recommend the use of the instrument to assess the self-perception of the spine in adolescents. For future translations and adaptations, we recommend the use of the COSMIN guidelines