Deterioration of the Swallowing Function Among Patients with COVID-19: A Propensity Score-Matched Cohort Study

Objective This study aimed to investigate whether the swallowing function deteriorates more significantly following coronavirus disease (COVID-19) infection in comparison to other viral respiratory infections in patients with mild to moderate (grade 2) COVID-19. Methods We conducted a propensity score-matched cohort study at St. Luke's International Hospital in Tokyo, Japan, from January 2010 to March 2024. Elderly patients (≥70 years) admitted for viral respiratory infections, including influenza and COVID-19, were included. Patients with suspected bacterial infections, patients who were incapable of oral intake at admission (including those with enteral nutrition and gastrostomy), and patients who died during hospitalization were excluded. The primary outcome was deterioration in the swallowing function, defined as downgrade in food texture category from admission to discharge. Results During the study period, 505 COVID-19 patients and 242 patients with other viral infections were admitted. The mean age was 81.7 years (±7.6) and 401 patients (53.7%) were male. Patients with COVID-19 showed a significantly higher rate of swallowing deterioration in comparison to patients with other viral infections (44.7% vs. 36.6%, p=0.04). Specifically, among patients who consumed a full diet at admission, those with COVID-19 had a higher rate of swallowing deterioration than those with other viral infections (41.9% vs. 31.7%, p<0.01). Conclusion COVID-19 was associated with a significant higher rate of downgrade in the food texture category in comparison to other viral respiratory infections, suggesting a potential impairment in the swallowing function. Given that this deterioration may contribute to prolonged hospitalization in COVID-19 patients, early intervention aimed at restoring and supporting swallowing function is warranted.