Evaluation of the validity and reliability of a self-assessment questionnaire for cosmetic outcomes after thyroidectomy: a cross-sectional validation study

Purpose The Self-Assessment Questionnaire for Cosmetic Outcomes (SAQCO) was developed by us to evaluate the cosmetic outcome of patients after thyroidectomy. This study aimed to examine the reliability and validity of SAQCO. Methods We analyzed the cosmetic outcomes of 368 patients who underwent thyroidectomy and completed the SAQCO 1 year after surgery. The one-dimensionality, reliability, and validity of SAQCO were assessed using factor analysis models, Cronbach’s alpha, and test–retest statistics. The differences in cosmesis indices between patient characteristics and surgical parameters were analyzed through comparative and regression analyses. Results The unidimensional convergence of SAQCO was examined. A Cronbach’s alpha of 0.91, strong item-total correlation values (from 0.77 to 0.89), and a test–retest correlation value of 0.86 indicated the internal consistency and reliability of the SAQCO. The cosmesis index was significantly highest in the transoral (92.3 points) and transaxillary groups (90.9 points), followed by the postauricular (84.8 points) and transcervical groups (76.4 points). Conclusion This study examined the reliability and validity of the SAQCO and showed that it is a suitable questionnaire for assessing cosmetic satisfaction of patients after thyroidectomy. The transoral and transaxillary approaches yield significantly superior cosmetic results compared to the conventional transcervical and postauricular approaches.