Validation of the Healthy Reference Range for, and Age and Sex Effects on the Sydney Swallow Questionnaire: A North American Sample

Purpose: The Sydney Swallowing Questionnaire (SSQ) is a validated 17 question self-report inventory measuring the severity of oropharyngeal dysphagia symptoms. Normative data from 73 Australian adults (45 male) without dysphagia were reported by Szczesniak et al. (2014). A mean total score (out of the possible 1700) was 59 (standard deviation [SD] 57, range 2 to 241) and the upper limit of the reference interval was 234 (90% CI [193, 277]). No significant effects of age or sex were found. The purpose of the current study was to determine the healthy reference interval, and age and sex differences in SSQ scores (total and subscores) in a new North American sample of adults reporting no history or symptoms of dysphagia.Methods: Participants were recruited as part of a larger study exploring videofluoroscopic measures of swallowing in healthy adults, who reported no history or symptoms of dysphagia or related medical conditions. Participants at 3 North American sites completed either a REDCap electronic or paper-based version of the SSQ. As in the original Szczesniak study, a Box-Cox transformation was applied to normalize score distribution prior to calculating reference interval boundaries using Reference Value Advisor software. Spearman’s and point bi-serial correlations were performed in SPSS to explore age and sex effects, respectively. Post-hoc Kruskal-Wallis tests explored differences across four quartile-defined age cohorts.Results: The sample comprised 159 adults (75 male) with a mean age of 53 years (range 19-90). Mean total SSQ score was 65.3 (SD 64, range 1 to 325). The upper limit of the reference interval was 233 (90% CI [197, 275]. There were no significant sex differences. A weak correlation (σ =.24) suggested higher scores in older participants. Post-hoc tests confirmed significantly higher scores in participants aged ≥ 73 compared to those aged ≤ 35 (p = .03) overall, and for questions regarding thin liquids, hard or dry foods, perceived difficulty and swallowing-related quality of life.Conclusions: These data from a new North American sample corroborate previous reports regarding SSQ scores in adults without symptoms or history of dysphagia, suggesting an upper limit of 233 for SSQ total score (90% CI 197, 275). In individuals over age 73, higher scores for select questions, as well as higher overall score may be expected.