Fine-tuned evaluation of olfactory function in patients operated for nasal polyposis

Given the forced-choice procedure of the identification test, patients with profound anosmia are more likely to have higher identification scores by chance than patients with hyposmia or normosmia. This may be a confusing factor when assessing the sense of smell, which alters the appreciation of real olfaction improvement. The aim of this study was to fine-tune the results of the identification Sniffin' Sticks test before and 6 weeks after surgery using the real identification score. A total of 133 patients underwent the Identification (I) and Threshold (T) tests the day before and 6 weeks after nasalization surgery. The scores of the identification test, called I _G (global identification), were ranked from 0 to 16. Patients had to specify if their forced-choice answers were given either surely or randomly, called I _H (hazard identification). The real score of identification I _R was obtained as follow: I _R = I _G - I _H. Patients with an immeasurable threshold according to the T test were more prone to give randomly correct answers. On the basis of I _G scores, 43.6% of patients remained hypo-anosmic after surgery compared to 72.9% before surgery. Using I _R scores, only 3.8% of patients remained anosmic (I _R = 0) at 6 weeks after surgery. Hence, patients with real anosmia (I _R = 0) were less prone to improve their olfaction than patients with I _R > 0. The analysis of random factor when using identification test allows differentiating a real anosmia from a hyposmia. An I _G ≤ 4 could be considered as a profound/real anosmia or a severe hyposmia. This procedure cannot, however, replace the forced-choice method in odor identification testing.