The QOD proved to be a valid, reliable, and easy-to-use method of assessment of olfaction-related QoL with high specificity and sensitivity.

The predictive value of olfaction for quality of life (QoL) recovery after endoscopic sinus surgery (ESS) in chronic rhinosinusitis (CRS) is still underestimated. The aim of this study was to explore the proportion of patients suffering from CRS who experience clinically significant QoL improvement after ESS and identify pre-operative clinical phenotypes that best predict surgical outcomes for QoL, focusing mainly on the role of patients' olfaction. One hundred eleven patients following ESS for CRS and 48 healthy subjects were studied. Olfactory function was expressed by the combined "Threshold Discrimination Identification" score using "Sniffin' sticks" test pre-treatment and 12 months after treatment. All subjects completed validated, widely used QoL questionnaires, specific for olfaction (Questionnaire of Olfactory Deficits: QOD), for assessing psychology (Beck Depression Inventory: BDI) and for general health (Short Form-36: SF-36). Statistically significant improvement of olfactory function by 41.8% and of all QoL questionnaires scores (all p < 0.001) was observed on the 12-month follow-up examination. Clinically significant improvement for QoL was measured in a proportion of 56.8% of patients on QOD, 64.9% on SF-36 and 49.5% on BDI scales results. Although olfactory dysfunction, nasal polyps, female gender, high socio-economic status and non-smoking habits were significantly associated with better QoL results, multivariate logistic regression analysis revealed that only olfactory dysfunction and nasal polyps were independent predictors significantly associated with higher likelihood of clinically significant improvement in all QoL questionnaire results. Olfactory dysfunction and nasal polyps were independent pre-operative predictors for surgical outcomes with regard to QoL results.

Olfactory dysfunction was found to decrease QoL among patients. Anosmia, CRS disease, and asthma as clinical predictors were proved to be independently correlated with QoL, anxiety, and depression levels.

QoL and mental health of patients suffering from chronic sinonasal diseases are totally recovered after treatment, presenting a direct positive relationship with smell improvement. An increase of olfactory function by 3.50 points for AR and 4.75 points for CRS might be considered the cutoff point for patients' QoL significant recovery.

Olfactory loss in chronic sinonasal diseases was found to be associated with anxiety and depression symptoms. Moreover, anxiety was correlated with depression. With regard to patients' demographics, female gender and low socioeconomic status proved to be independently correlated with anxiety and depression levels.