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Salivary Viscosity as a Non-Invasive Candidate Biomarker Associated With Aspiration Risk in Oculopharyngeal Muscular
Alex Zvulunov1,2,3,4, Rawan Saif5, Liraz Olmer6
1The National Specialized Multidisciplinary Service for OPMD Patients, Sheba Medical Center, Tel Hashomer, Israel.
Background:
Aspiration pneumonia is the leading cause of morbidity and mortality in oculopharyngeal muscular dystrophy (OPMD), yet non-muscular contributors to aspiration risk are poorly defined. Thick saliva is frequently reported but has never been quantitatively characterised.
Objectives:
The primary objective was to compare salivary kinematic viscosity in genetically confirmed patients vs. household controls. Secondary hypothesis-generating exploratory objectives were to examine associations between viscosity, dysphagia severity, and aspiration risk.
Methods:
In this observational, cross-sectional study, we compared genetically confirmed OPMD patients with matched household controls. Salivary kinematic viscosity was the primary outcome. Exploratory assessments examined associations between viscosity and validated dysphagia measures (Swallowing Disturbance Questionnaire, Penetration-Aspiration Scale, Functional Oral Intake Scale) and oral health (number of decayed, missing, and filled teeth).
Results:
Among 57 participants (30 OPMD, 27 controls), salivary viscosity was higher in patients (difference 0.85 cSt; 95% CI 0.27-1.44; p = 0.007) and remained independently associated with the disease status after adjustment for age, oral health, and "xerogenic" medications. Higher viscosity was independently associated with higher aspiration risk (adjusted OR 2.5 per 1 cSt; 95% CI 1.1-6.1; p = 0.040), and discriminated patients with high risk for aspiration (Area Under the Curve of 0.76 and a positive likelihood ratio of 10.0). Salivary flow rates were preserved, indicating a compositional rather than hyposecretory rheological shift.
Conclusion:
Oculopharyngeal muscular dystrophy is associated with a flow-independent shift in salivary rheology quantitatively linked to dysphagia severity and aspiration risk. These cross-sectional findings nominate salivary viscosity as a non-invasive candidate biomarker warranting prospective validation for clinical application.
