Reliability and validity of a novel simple postural assessment of swallowing

This study was aimed at developing a simple posture test for swallowing and confirming its reliability (intra- and inter-rater), criterion validity, and construct validity as a tool for the early identification of patients with dysphagia requiring early physiotherapy intervention.

We developed a posture test involving measurement of the external occipital protuberance and the seventh cervical vertebra distance (OC7), along with the chin-chest distance (CCD). This test was designed to be a simple, sit-down assessment related to swallowing.

Thirty-six elderly subjects (mean age = 84.7 ± 7.2 years) attending day rehabilitation were included in this study. Participants who were not taking oral nutrition, those with restricted cervical movements due to cervical fusion surgery or from using a cervical collar, and those with significant cognitive decline were excluded. The following data were recorded for all participants: age, sex, head range of motion (ROM), OC7 in resting position, maximum cervical extension, maximum cervical flexion, CCD, genio-thyroid distance (GT), thyroid-sternum distance (TS), and results of the repetitive saliva swallowing test (RSST) and eating assessment tool-10 (EAT-10).

Statistics were obtained for ROM, OC7, CCD, GT, and TS using Intraclass correlation coefficients (ICC) (1.1) for intra-rater reliability and ICC (2.1) for inter-rater reliability.

For criterion-related validity, we tested the correlations of head ROM and GT, TS, and GT+TS distances with OC7 and CCD. For construct validity, we assessed the correlations between RSST and EAT10 and the other items. The normality of data distributions was assessed using the Shapiro–Wilk test. Accordingly, Pearson’s product-moment correlation or Spearman’s rank correlation coefficients were used as applicable.

We observed good to excellent intra- and inter-rater reliability for all items (ICC = 0.29–0.98). For criterion-related validity, significant correlations were found between OC7 (resting) and extension ROM, flexion-extension ROM and OC7 extension and OC7 flexion-extension, OC7 flexion and TS and GS+TS, TS, GS+TS, CCD with TS, GS+TS. Lastly, significant correlations were found only between RSST and flexion-extension ROM and OC7 extension.

Reliability (intra- and inter-rater), criterion validity and construct validity were observed for the simple posture test for swallowing; however, a statistically significant relationship could not be established between the developed test and swallowing. Further studies are warranted to validate the test in severe cases of swallowing and develop cutoff values.

The OC7 and CCD values are simple methods for assessing swallowing-related neck posture that can be performed in a sitting position. We intend to use these values for the early identification of patients with posture-related swallowing problems in clinical settings and provide timely physiotherapy intervention.