Olfactory training is helpful in postinfectious olfactory loss: A randomized, controlled, multicenter study

Objectives/Hypothesis The aim of this study was to evaluate the effects of olfactory training (OT) on olfactory function in patients with persistent postinfectious olfactory dysfunction (PIOD). Study Design Randomized, single-blind, controlled, multicenter crossover study. Methods Twelve tertiary university medical centers participated. Investigations were performed at three visits (baseline, after 18 weeks, and after 36 weeks), including only subjects with PIOD of <24-months duration. At each visit, participants received detailed assessment of olfactory function. Seventy subjects trained with high concentrations of four odors for 18 weeks; the other half (n = 74) trained with low concentrations of odors. For the following 18 weeks this regimen was switched. Results After 18 weeks, olfactory function improved in the high-training group in 18 of 70 participants (26%), whereas only 11/74 improved in the low-training group (15%). In subjects with a duration of olfactory dysfunction of <12 months, olfactory function improved in 15/24 participants (63%) of the high-training group and in 6/31 participants (19%) of the low-training group (P = .03). Conclusions OT improves PIOD, and the use of odors at higher concentrations is beneficial to improvement. OT is a safe procedure and appears to be particularly useful in patients who start OT within 12 months after the onset of the disorder. OT is the first successful therapy regime in patients with PIOD. Level of Evidence 1b. Laryngoscope, 124:826-831, 201

Association between olfactory function and quality of life in patients with olfactory disorders: a multicenter study in over 760 participants

Background: This cross-sectional, multi-centric study aimed to investigate the differences in quality of life among patients with olfactory dysfunction (OD) of different origin, and to identify factors associated with olfactory-related quality of life (QOL). Methods: Seven hundred sixty-three adults were recruited from 8 Smell & Taste clinics in Germany, Switzerland, and Austria. Olfactory-related QOL was assessed by the Questionnaire of Olfactory Disorders (QOD). Olfactory function was assessed with the Sniffin' Sticks test; self-assessment was performed with visual analog scales. Results: Patients with post-infectious and post-traumatic OD showed poorer olfactory-related QOL than patients with sinonasal and idiopathic OD. The olfactory-related QOL was positively associated with the Sniffin' Sticks test score, self-assessed olfactory function, disease duration, and age, with younger olfactory dysfunction patients showing lower QOL. Female patients presented with poorer olfactory-related QOL. In addition, the results showed that self-assessment of olfactory function explained more of the variance in olfactory-related QOL than olfactory function evaluated by the Sniffin' Sticks test. Conclusions: In addition to the psychophysical testing results, several factors such as disease cause, disease duration, sex, or self-assessed olfactory dysfunction should be taken into account when assessing the individual severity of the smell loss