Translation, cultural adaptation and validation of the Stapesplasty Outcome Test 25 (SPOT-25) for measurement of disease-specific health-related quality of life in Dutch otosclerosis patients: a prospective study

Abstract

PURPOSE: To translate and culturally adapt the SPOT-25 to the Dutch language and validate the Dutch SPOT-25 in a Dutch population of otosclerosis patients undergoing primary stapes surgery. METHODS: A multicenter prospective validation study was performed between November 2018 and May 2024. The translation into Dutch and validation process of the SPOT-25 was performed according to the COSMIN guidelines. Patients were asked to complete the SPOT-25 and Glasgow Health Status Questionnaire (GHSQ) preoperatively, the SPOT-25, GHSQ and Glasgow Benefit Inventory six to eight weeks postoperatively and the SPOT-25 eight to ten weeks postoperatively. Healthy controls were asked to complete the translated SPOT-25 once. Preoperative and postoperative audiometric results were also obtained. The evaluated measurement properties included construct validity, measurement invariance, discriminative validity, reliability and responsiveness of the translated SPOT-25. RESULTS: Hundred and fifteen patients and 50 healthy controls were analyzed. Analyses of the translated SPOT-25 showed adequate construct validity, discriminative validity, reliability and responsiveness. The SPOT-25 scores were strongly correlated with the GHSQ score. The internal consistency and test-retest reliability were good as Cronbach's alpha and intraclass correlation coefficients were higher than 0.70. The four-factor model fitted best in our population of otosclerosis patients; however the results indicated a mediocre fit between the model and the data. CONCLUSION: The Dutch SPOT-25 showed good validity, reliability and responsiveness and can be implemented as an additional outcome measure to improve otosclerosis research and clinical practice.