Parosmia is Associated with Relevant Olfactory Recovery After Olfactory Training

Abstract

Objective/hypothesis: This study aims to determine the association between parosmia and clinically relevant recovery of olfactory function in patients with post-infectious olfactory dysfunction (PIOD) receiving olfactory training.

Study design: Retrospective cohort study.

Methods: This was a retrospective cohort study of patients with PIOD that received olfactory training. Adult patients with the major complaint of quantitative smell loss were recruited and treated at several ENT clinics in German between 2008 and 2018. The outcome was based on the association between smell-loss related factors (including parosmia and phantosmia) and clinically relevant changes in overall and subdimension olfactory function of threshold, discrimination, and identification using binary logistic regression analysis.

Results: A total of 153 participants with PIOD were included. Clinically relevant improvements in overall olfactory function were more likely in those that had lower baseline olfactory function. Relevant improvements in discrimination function were more likely in those that had lower baseline olfactory function and those that had parosmia at the initial visit. Similarly, relevant improvements in odor identification were more likely in those that had a lower baseline olfactory function and in those who had parosmia at the first visit. Clinically significant improvements in odor threshold were more likely in those who were older in age.

Conclusions: This study demonstrated that the presence of parosmia is associated with clinically relevant recovery in olfactory discrimination and identification function in patients with PIOD receiving olfactory training.

Level of evidence: 4 Laryngoscope, 131:618-623, 2021.

Keywords: Smell; anosmia; hyposmia; olfaction; olfactory training; parosmia; smell loss.