Swallowing Safety Across the Lifespan: Reference Flexible Endoscopic Evaluation of Swallowing Data in Healthy Adults

The aim of this study was to establish reference values for swallowing safety using flexible endoscopic evaluation of swallowing (FEES) in healthy adults across the lifespan and to examine the influence of age, sex, bolus characteristics, and snoring on the risk of unsafe swallowing.

A prospective cross-sectional study was conducted with 128 healthy adults (21-91 years). Participants underwent a standardized FEES protocol involving 20 bolus trials across four consistencies and volumes. Swallowing safety was rated using the Penetration-Aspiration Scale (PAS) and secretion management using the New Zealand Secretion Scale (NZSS). A generalized linear mixed-effects model was used to identify person or bolus characteristics that are risk factors for unsafe swallowing (PAS ≥ 3).

Most participants (95%) exhibited normal secretion (NZSS = 0); abnormal secretion was observed only in men (> 40 years old) but showed the predominant prevalence (25%) in men over 80 years old. Unsafe swallowing occurred in 9.4% of participants, with trace aspiration (≤ 10% bolus) in nearly all cases. An increased number of swallows per bolus was linked to higher risk (odds ratio [OR] = 3.7; 95% confidence interval [CI] [1.90, 7.22]), whereas the extremely thick consistency (International Dysphagia Diet Standardisation Initiative, Level 4) was associated with reduced risk (OR = 0.06; 95% CI [0.01, 0.42]; p < .005). Older men had significantly higher odds of unsafe swallowing than younger men (OR = 15.3; 95% CI [2.94, 79.3]; p = .001); however, a larger sample size is required to more closely estimate the magnitude of this effect. Women showed no significant effect of increasing age. Snoring was not associated with a significantly increased risk of unsafe swallowing.

This study provides comprehensive reference FEES data for swallowing safety in healthy adults. Sex, age, bolus consistency, and number of swallows significantly influence swallowing outcomes. These findings support more accurate interpretations of FEES in clinical dysphagia assessment and management.