A novel objective olfactory assessment method based on nasal airflow changes following eugenol stimulation.

Abstract

Background: Current olfactory assessment relies on subjective scales or complex objective techniques. A simple, economical objective method is needed.

Objectives: This study evaluated a nasal airflow-based olfactory assessment using eugenol stimulation.

Material and methods: Four hundred and twelve participants underwent VAS scoring, Sniffin' Sticks testing, and nasal airflow assessment with 2.5% eugenol. Correlation, group comparison, cluster analysis, and ROC analysis were performed. A validation cohort (n = 56) and test-retest reliability (n = 30) were also assessed.

Results: Velocity change ratio showed weak correlations with discrimination (r=-0.10, p = 0.03), identification (r = 0.09, p = 0.04), and VAS scores (r = 0.05, p = 0.02). The OD group showed lower flow and velocity change ratios than controls (p < 0.001 and p = 0.03). Cluster analysis yielded cut-offs of <4% (flow) and <2.5% (velocity). In the validation cohort, AUC was 0.71 (95% CI: 0.56-0.86), sensitivity 72.7%, specificity 91.7%. Test-retest ICCs were 0.76 and 0.83.

Conclusions: The nasal airflow-based assessment shows weak correlations with established tests and modest diagnostic accuracy. Its simplicity makes it potentially suitable as a screening tool, but it cannot replace comprehensive psychophysical testing.