Dysphagia Prevalence in Progressive Supranuclear Palsy: A Systematic Review and Meta-Analysis.

Most people in the included studies had moderate PSP. The authors say the pooled figures do not represent people in the early or late stages of the disease. Several studies excluded people with severe dysphagia, men and women were unevenly distributed, and most samples were small (median 24 people), so the people with the worst swallowing problems are likely under-represented. The studies used convenience samples rather than random ones, which the authors rate as a high risk of selection and coverage bias. Only 12 studies were included, they assessed swallowing in different ways, and the pooled dysphagia figure varied considerably between them. Some studies judged swallowing with a water swallow test, which the authors note was validated in stroke and not in people with PSP, and these tests produced the lower prevalence figures. Estimating how common dysphagia is was not the main aim of the included studies, and one reviewer rather than two extracted the data and rated study quality, a deviation from the registered protocol.

The paper's only funding statement names the University of Dublin, Trinity College. No other funding source, sponsor role or conflict of interest is reported in the text.

Do not read the pooled 79% as the prevalence at any point in the disease. Most participants in the included studies had moderate PSP, several studies excluded people with severe dysphagia, and the figure changes from 56% to 89% depending on whether dysphagia was identified by a water swallow test or by instrumental assessment. The 24% aspiration figure is for water swallows only and the authors expect it to rise as the disease progresses.