Shinichi Watanabe, Takaaki Sakurai, Takahiro Kanaya, Takumi Iwasaki, Hyosuke Oshima, Tetsuya Furukawa, Tomohiro Yoshikawa, Seichi Nakahashi, Yasunari Morita
Dysphagia is a complication of coronavirus disease 2019 (COVID-19), often attributed to intubation and critical illness. However, the recovery trajectory in non-intubated patients with COVID-19 compared with that in patients with other pneumonia types remains unclear. This retrospective cohort study included non-intubated adults hospitalized with pneumonia between May 2022 and December 2023, comparing COVID-19 and non-COVID pneumonia patients regarding time to functional oral intake (Functional Oral Intake Scale [FOIS] ≥ 4) and longitudinal FOIS changes. Two Cox proportional hazards models were fitted: Model 1 estimated the total effect (pre-exposure variables only), and Model 2 estimated a conditional association after further adjustment for post-exposure rehabilitation variables. A linear mixed-effects model was used for the longitudinal analysis. Of the 431 patients (168 COVID-19, 263 non-COVID), the COVID-19 group had significantly delayed initiation of oral intake and speech therapy. In Model 1, COVID-19 was associated with a 44% lower hazard of achieving FOIS ≥ 4 (HR 0.56; 95% CI, 0.42-0.76; p = 0.0001). In Model 2, this attenuated to null (HR 1.03; 95% CI, 0.73-1.46; p = 0.876), and a time-dependent Cox sensitivity analysis was concordant (HR 0.88; 95% CI, 0.63-1.23; p = 0.465). Higher pre-hospital frailty, delayed oral intake, and lack of direct swallowing training independently predicted slower recovery. These findings indicate that the slower recovery observed in patients with COVID-19 was largely attributable to delays in oral intake and rehabilitation rather than to COVID-19 itself, supporting early oral intake and equitable direct swallowing training under infection control constraints.