Purpose: Patient-reported outcomes (PRO) assessing dysphagia are an essential component of clinical trials to consider how patients feel and function in response to treatments. The selected PRO needs to be translated in several languages using a systematic process ensuring its validity and equivalence for use in multicenter clinical trials. The main objectives were to translate the SWAL-QOL and the Sydney Swallow Questionnaire (SSQ) into French Canadian (SWAL-QOL-FC and SSQ-FC) and to assess their appropriateness for patients with oculopharyngeal muscular dystrophy (OPMD).
Methods: A forward- and back-translation process was followed including independent mother-tongue translators followed by committee review. Known-groups validity was assessed by comparing scores of OPMD French-Canadian participants (n = 21) known to differ in dysphagia severity according to the 80-ml drinking test score. A Mann-Whitney test was used to compare the mean scores. Cognitive interviews were conducted later on to ensure a posteriori cultural equivalence among French-Canadian participants (n = 28).
Results: Evidences of adequate known-groups validity was shown for the SSQ-FC. Only two domains out of 10 of the SWAL-QOL-FC (burden and eating duration) showed adequate known-groups validity. In addition, the difference in the mean composite score was not significant. Several conceptual equivalence issues were found in both questionnaires as a result of the cognitive interviews.
Conclusion: This study provided evidence that the SSQ-FC presents better validity than the SWAL-QOL-FC in a small sample size of OPMD participants. The findings of the cognitive interviews suggest the need to develop an OPMD-specific questionnaire to capture better the whole spectrum of disease severity.
Keywords: Cross-cultural adaptation; Dysphagia; Known-groups validity; Oculopharyngeal muscular dystrophy; SSQ; SWAL-QOL.
© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.