Parosmia is associated with relevant olfactory recovery after olfactory training

Abstract

Objectives This study aims to determine the association between parosmia and clinically relevant recovery in olfactory function in patients with smell loss receiving olfactory training. Design and setting This was a retrospective cohort study of patients 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. Participants A total of 243 participants were included. Main outcome measures Changes in olfactory function after olfactory training. Age, gender, baseline olfactory function, etiology and duration of smell loss, duration of training, and presence of parosmia and phantosmia were assessed for their impact on clinically relevant changes in overall and subdimension olfactory function using binary logistic regression analysis. Results Relevant improvements in discrimination function were more likely in those that had lower baseline olfactory function, postinfectious reasons compared to posttraumatic or idiopathic causes and those that had parosmia at initial visit. Relevant improvements in odour identification were more likely in those that had a lower baseline olfactory function, female gender, and in those who had parosmia at the first visit. Clinically significant improvements in odour threshold were more likely in postinfectious causes compared to posttraumatic reasons and those who were older in age. Conclusions This study demonstrated that the presence of parosmia is associated with clinically relevant recovery in olfactory function in patients with smell loss receiving olfactory training. Key points 1. Parosmia is associated with clinically relevant improvements in discrimination and identification function in patients with smell loss receiving olfactory training. 2. Clinically relevant recovery of overall olfactory performance was more likely in those that had lower baseline olfactory function at initial visit and in postinfectious smell loss compared to posttraumatic or idiopathic causes. 3. Recovery of suprathreshold olfactory function discrimination and identification was distinct from threshold improvements.

Qualitative Olfactory Disorders: Patient Experiences and Self-Management

“…Fifth Sense, the UK charity for people affected by smell and taste disorders, was founded in 2012 and working together with patients our previous work has been able to demonstrate the very significant impact of olfactory disorders on those affected. 12 , 13 Whilst recent findings show that qualitative disorders may have a positive prognostic significance for the recovery of olfactory disorders 14 they do however present a particular source of distress to those affected whilst present. Previous studies of patients presenting with olfactory dysfunction have shown that parosmia was present in 34% and phantosmia present in 12% of patients presenting to a clinical setting.…”

International consensus statement on allergy and rhinology: Olfaction

“…1543,1544,1617 A retrospective cohort study of 153 patients with PIOD undergoing OT therapy found that the presence of phantosmia failed to be associated with clinically relevant improvement in OF, but this only points away from phantosmia being a positive predictive factor and does not elucidate whether OT may be helpful for phantosmia itself in some patients. 1618 No clinical trials have been performed on this subject.…”