Swallowing impairment and aspiration risk in clinically stabilized patients hospitalized for acute respiratory events: a cohort-wide machine-learning analysis with COPD-specific insights

Objectives To characterize swallowing impairment and aspiration risk in patients recovering from acute respiratory events and to identify clinical, functional, and anatomical predictors of airway invasion with a specific focus on Chronic Obstructive Pulmonary Disease (COPD) subgroup. Methods In this retrospective cross-sectional study, adults hospitalized for pneumonia or acute respiratory failure underwent videofluoroscopic swallowing study (VFSS) after clinical stabilization. Airway invasion was graded using the Penetration–Aspiration Scale (PAS). Predictors of aspiration (PAS ≥ 6) were explored using multivariable logistic regression with bootstrap confidence intervals and age-adjusted marginal standardization. A Random Forest model was used to assess discrimination and identify key predictors, including a dedicated analysis in the COPD subgroup. Results A total of 101 patients were included [mean age 60 years (range 17–85); 58.4% male]. Among them, 25 exhibited aspiration and 20% penetration despite clinical stabilization; nearly half of COPD patients fell within PAS 6–8. Vallecular and hypopharyngeal residue increased progressively across PAS categories, rising from 52 and 25% in PAS 1–2 to 84 and 100% in PAS 6–8, respectively, consistent with a severity-dependent pattern of impaired bolus clearance and increased vulnerability to airway invasion. Age-adjusted aspiration risk varied across pathologies, with the highest probabilities observed in neuromuscular diseases. The Random Forest model showed good discrimination (AUC = 0.90), identifying age and recent bronchitis as influential predictors. In COPD, semisolid aspiration and vallecular residue emerged as the most relevant physiologic predictors across both regression and machine-learning analyses. Conclusion Swallowing impairment and aspiration are frequent after acute respiratory events, including in COPD. Recent bronchitis and pharyngeal residue represent clinically relevant markers of aspiration risk. Early, structured swallowing assessment may help identify vulnerable patients and guide targeted interventions to reduce aspiration-related respiratory morbidity.