Background: Determination of predictive factors and specific values of olfactory function after endoscopic sinus surgery (ESS) using objective diagnostic methods may support consultation of respective patients. This study was designed to assess the longitudinal olfactory functional outcome after ESS in patients with severe chronic rhinosinusitis (CRS) with nasal polyposis, to evaluate associated clinical factors and to provide statistical models for prediction of olfactory recovery.
Methods: One hundred sixteen patients with nasal polyposis refractory to medical treatment underwent ESS. Olfactory testing was performed preoperatively and 1, 3, and 6 months after surgery using "Sniffin' Sticks" (Burghardt, Wedel, Germany). Using multivariate linear and logistic regression analysis, statistical models were generated to predict (i) the 6th-month composite threshold-discrimination-identification (TDI) score and (ii) the probability of attaining normal olfaction at 6 months.
Results: A significant stepwise increment of all olfactory function indices was found over time. Factors influencing final olfactory recovery were patients' age, duration of olfactory deficit, previous paranasal sinus surgery, and aspirin-exacerbated respiratory disease. The first model explained 70% of the observed variation in postoperative TDI scores. The second model correctly classified 76% of the patients.
Conclusion: A significant progressive improvement of olfaction for at least 6 months was observed after ESS. The statistical models developed may be useful for consultation of ESS candidates in clinical practice.