The Dysphagia Outcome and Severity Scale (DOSS) and non-instrumental swallowing measures in amyotrophic lateral sclerosis

Purpose: To evaluate reliability of the Dysphagia Outcome and Severity Scale (DOSS) in Amyotrophic Lateral Sclerosis (ALS) patients, and to assess diagnostic accuracy of selected non-instrumental measures in defining swallowing safety in this population. Methods: One hundred and thirteen consecutive ALS patients underwent comprehensive dysphagia evaluation with fiberoptic endoscopic evaluation of swallowing (FEES) and were classified according to DOSS. Safe and unsafe swallowing were defined by DOSS levels 7-6 and 5-1, respectively. Patient-reported measures included ALS Functional Rating Scale-Revised swallow item (I-3) and Eating Assessment Tool-10 (EAT-10). Non-instrumental clinical measures were hyolaryngeal excursion, voluntary cough (VC), voice quality and reflexive cough/throat clearing (VRC), and maximum phonation time (MPT). Inter- and intra-rater reliability were assessed using weighted Cohen's kappa and Fleiss' kappa coefficients. Non-instrumental measures diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis. Results: Twenty-six of 113 patients (23%) exhibited an unsafe swallowing. Inter- and intra-rater agreement for DOSS classification was excellent across raters. EAT-10 and a composite clinical index derived from VC, VRC, and MPT showed the highest diagnostic accuracy with area under the curve values of 0.790 and 0.832, respectively. Other non-instrumental measures demonstrated lower discriminative performance. Conclusions: The DOSS showed an excellent reliability when applied to FEES in patients with ALS, supporting its use as a functional classification tool with direct nutritional and management implications. Non-instrumental measures should be interpreted with caution and confined to a triage role rather than diagnostic decision-making, particularly in light of the rapid progression of dysphagia in ALS.