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Characterisation of patients with idiopathic olfactory dysfunction and plan for clinical follow-up.

INTRODUCTION
Characterisation and management of olfactory dysfunction (OD) can be challenging, especially in patients diagnosed with idiopathic OD. This group of patients is at risk of developing neurodegenerative diseases such as Parkinson's disease, wherefore appropriate guidelines for management of OD are needed. We aimed to identify and characterise patients suffering from idiopathic hyposmia/anosmia.


METHODS
This prospective study included 515 consecutive patients referred to the Flavour Clinic, Holstebro, Denmark. Patients with idiopathic, sino-nasal or post-infectious OD were compared with regards to symptoms and clinical findings including endoscopy of the upper airways, sino-nasal CT, allergy testing, and olfactory and gustatory assessment.


RESULTS
Patients with idiopathic OD were older and a preponderance of females was observed compared with the sino-nasal group (p = 0.0302, and p = 0.0549, respectively). The OD group had a lower prevalence of allergy and longer symptom duration than both the sino-nasal and the post-infectious groups (p Less than 0.0001 and p = 0.0014; p less than 0.0001 and p less than 0.0001, respectively).


CONCLUSIONS
Patients suffering from idiopathic OD were predominantly females with a long symptom duration. Only few of these patients suffered from allergies or sino-nasal pathologies. Patient history, the Sino-Nasal Outcome Test and threshold discrimination identification scores from the Extended Sniffin Sticks test are the most valuable clinical tools for diagnosing the aetiology behind OD. An ideal workup for idiopathic OD is presented.


FUNDING
none.


TRIAL REGISTRATION
not relevant.