The German Sydney Swallow Questionnaire: Reliability and validity in patients with oropharyngeal dysphagia

Abstract

Background: The Sydney Swallow Questionnaire (SSQ) is a self-report inventory assessing subjective symptoms of oropharyngeal dysphagia with strong content, construct, discriminant, and predictive validity and test–retest reliability in a range of patient populations. Objective: The main aim of this work was to assess the validity and reliability of the German version of the SSQ (SSQ-G). Materials and methods: In a cross-validation study, 48 adult German-speaking patients (12 women, 36 men) with neurogenic (n = 16), structural (n = 16), and functional (n = 16) oropharyngeal dysphagia were assessed with the SSQ‑G and the MD Anderson Dysphagia Inventory (MDADI). Cronbach’s α was applied to assess the reliability. Criteria and construct validity were investigated using the Spearman correlation coefficient. Results: With Cronbach’s α = 0.94, the internal consistency of the SSQ‑G was excellent. The SSQ‑G questions 1 and 17 showed a moderately significant and highly significant correlation coefficient of −0.43 and −0.45, respectively, with MDADI question 1 (p < 0.5, p < 0.001). Between questions 8, 11, and 12 of the SSQ‑G and questions 7, 13, and 10 of the MDADI, coefficients of −0.48 to −0.55 showed a moderate to strong highly significant correlation (p < 0.001). Thus, the reliability and criterion and construct validity were statistically confirmed. Conclusion: The German version of the SSQ (SSQ-G) allows a reliable and valid assessment of functional swallowing difficulties. In combination with questionnaires on symptom-specific quality of life, such as the MDADI, a more differentiated clinical analysis of swallowing problems is thus possible.