The normative range for and age and gender effects on the Sydney swallow questionnaire (SSQ)

Abstract

The Sydney Swallow Questionnaire (SSQ) is a validated measure of the symptomatic severity of oral–pharyngeal dysphagia. Up until now no normative ranges have been established for the questionnaire. This is a limitation in its utility as it makes it difficult to use the tool to identify the prevalence and burden of oral–pharyngeal dysphagia in the general population or within patient populations. The study’s aim was to derive the normative range of dysphagia scores for the SSQ and to determine whether, in nondysphagic individuals, there are any age or gender effects on these scores. The questionnaire was administered to 73 eligible nondysphagic individuals who had been screened for any dysphagia or conditions that might predispose them to dysphagia. The frequency distribution of SSQ scores was first examined for normality and appropriate transformations performed before determining the upper limit of normal. Of the 73 healthy participants, 45 were male, and the cohort had a mean age of 58.6 years (range = 22.0–82.1 years). No statistically significant relationship between SSQ scores and either age (rs[73] = 0.140, p = 0.239) or gender (rpb[73] = 0.021, p = 0.857) was found. The mean total SSQ score (maximum possible score = 1,700) was 59.0 (SD = 56.7; range = 2–241). The frequency distribution of scores was non-normal and markedly skewed. After a Box–Cox transformation to normalise the distribution, the calculated upper limit of the reference interval was 234 with a 90 % CI of [193, 277]. The SSQ scores in a nondysphagic population are not influenced by age or gender. These data complement the existing reliability and validation data and thereby improve the overall utility of the SSQ in the context of future studies of oral–pharyngeal dysphagia prevalence, efficacy, and outcome.