Discrepancies between subjective and objective olfactory outcomes after FESS in CRSwNP: Predictive factors and...

Chronic rhinosinusitis with nasal polyps (CRSwNP) frequently leads to olfactory dysfunction, prompting patients to seek functional endoscopic sinus surgery (FESS) for improvement. However, predicting postoperative outcomes is challenging due to variability in improvement rates and discrepancies between subjective self-assessments and objective olfactory tests. This study aimed to identify preoperative clinical factors associated with discrepancies between subjective and objective postoperative olfactory outcomes, enabling better patient counseling and result prediction.

This retrospective study included 100 CRSwNP patients without a history of COVID-19-related olfactory dysfunction who underwent bilateral full-house FESS. Data analyzed included demographic characteristics, preoperative Lund-Mackay and olfactory cleft scores, blood eosinophils, immunoglobulin E levels, preoperative butanol threshold test (BTT) scores, subjective olfactory scores, parosmia status, and responses to pleasant odors. Postoperative olfactory outcomes were evaluated using the BTT and a 5-grade subjective olfactory function scale. Logistic regression identified predictive factors for discrepancies between subjective and objective outcomes.

Preoperative BTT score (β=-0.682, p < 0.001) and parosmia status (β=-0.214, p = 0.01) independently influenced objective olfactory outcomes, while subjective outcomes were affected by preoperative 5-grade olfactory function scale (β=-0.506, p < 0.001), eosinophil percentage (β=-0.218, p = 0.016), and parosmia (β=-0.182, p = 0.038). Lower preoperative 5-grade scores significantly predicted discrepancies (p = 0.001; odds ratio=0.335).

Discrepancies between subjective and objective olfactory outcomes after FESS are common, particularly in patients with severe preoperative subjective olfactory dysfunction. Excluding COVID-19-related cases, incorporating both psychophysical and subjective assessments pre- and postoperatively is critical for comprehensive evaluation and effective patient counselling.