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Use of the Penetration-Aspiration Scale in Dysphagia Research: A Systematic Review


The penetration-aspiration scale (PAS) is an 8-point scale used to characterize the depth and response to airway invasion during videofluoroscopy. Though widely used in the field of deglutition, there is a lack of consensus regarding the statistical properties of the scale. In order to better understand the state of the literature and the statistical use of the PAS, a systematic review was undertaken to descriptively examine trends in statistical and reporting practices of the PAS since its inception. Online databases were searched for studies citing the original PAS article, which yielded 754 unique articles. Of these, 183 studies were included in the review. Results showed inconsistencies in the statistical use of the scale; 79 studies treated the PAS as ordinal, 71 as categorical, and 49 as interval. Ten types of categorizations were identified. Reporting of power analyses (9%), as well as inter- (26%) and intra-rater (17%) reliability, was uncommon. Among studies that administered multiple bolus volumes or consistencies, 55% reported PAS analyses at the participant/group level only. This review confirms the existence of discrepancies in the statistical treatment of the PAS. A lack of consensus among researchers limits comparisons between studies. The approach to handling this scale dictates the statistical tests used, potentially affecting results and interpretations. Consistent application of statistically sound approaches to PAS analyses is vital for the future of deglutition research.

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Data Availability

Data are available on the Open Science Framework at the following url: https://osf.io/5m2r7/


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The authors would like to acknowledge Dr. Sonja Molfenter’s guidance and assistance with manuscript preparation.



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Borders, J.C., Brates, D. Use of the Penetration-Aspiration Scale in Dysphagia Research: A Systematic Review. Dysphagia (2019). https://doi.org/10.1007/s00455-019-10064-3

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  • Penetration-Aspiration Scale
  • Statistical analysis
  • Research trends
  • Deglutition