Validation and psychometric properties of the Turkish version of Neuromuscular disease Swallowing Status Scale (NdSSS) in patients with oro-pharygo-esophageal dysphagia in neuromuscular disorders

Objective: Dysphagia is one of the most disabling conditions arising from neuromuscular disorders(NMD). There is no specific methods to use in the evaluation of dysphagia in NMD patients. We aimed both to evaluate the applicability of the Neuromuscular Disease Swallowing Status Scale (NdSSS) for dysphagia in all phases of swallowing in various NMD patients and to investigate psychometric properties of this scale.

Methods: Patients with NMD were enrolled. Functional Oral Intake Scale (FOIS), Fiberoptic Endoscopic Evaluation of Swallowing (FEES), NdSSS and High-Resolution Esophageal Manometry (HRM) were performed on all subjects within 72 hours. While the convergent and concurrent validities were used as validation method, Cohen’s kappa and Cronbach’s alpha coefficient were calculated for inter-rater reliability. The correlation between FOIS, PAS and HRM diagnosis according to Chicago version 3.0 (CCv3) were analyzed.

Results: 115 NMD patients were included. There was good correlation between NdSSS and FOIS and PAS scores (Spearman’s rank correlation coefficient (r):0.927, r:0.927 and r:-0.836, r:0.841, respectively). Also, there was a positive good correlation between NdSSS and CCv3 evaluating disorders of esophageal peristalsis (r:0.677-0.679, p=0.001). When evaluated separately, there were good correlation between NdSSS levels; and PAS (r:-0.648-0.656); and CCv3 (r:0.514-0.573) levels for ALS. For Myasthenia gravis there was a good correlation between NdSSS levels; and CCv3 (r:0.577-0.622); FOIS (r:0.508-0.521); and PAS (r:-0.504-0.519) scores. Also, for myopathy; a very good(CCv3(0.976-0.982)) and good(FOIS (0.511-0.581) and (PAS (-0.516-0.550)) correlations were defined for myopathy.

Conclusion: The NdSSS was found applicable to detect both oropharyngeal and esophageal dysphagia risk in patients with NMD and is a valid and reliable swallowing screening tool that can evaluate oro-pharyngo-esophageal dysphagia in NMD patients.

Keywords: Dysphagia, neuromuscular disorders, neuromuscular disease swallowing status scale, NdSSS, myasthenia gravis, amyotrophic lateral sclerosis, non-inflammatory.