Olfactory Training as a Treatment for Olfactory Dysfunction Post COVID-19

Condition(s) studied

Investigational drug(s) / intervention(s)

Smell training: For 12 weeks, morning and evening, smell four different odors or four odorless substances for a total of five minutes per session.

Study summary

Olfactory dysfunction is a defining symptom of COVID-19 infection. Studies have demonstrated improved olfaction in patients with post infectious olfactory dysfunction after an olfactory training (OT). The aim of this study is to assess the clinical outcomes of olfactory training (12 weeks) therapy in the treatment of persistent olfactory dysfunctions after COVID-19. Specially, we aim to compare the effectiveness of two different olfactory training (different odors).

A group will train themselves with 4 scents (rose, orange, clove and eucalyptus) and another group with 4 different scents (cheese, coffee, strawberries and lemon). Olfaction sensory evaluation will be performed by using different olfaction tests (Sniffin' Sticks and UPSIT) and complete questionnaires to assess olfactory perception and particularly parosmia and phantosmia.

Eligibility

Primary outcome measure(s)

• Changes from baseline in olfactory score on the University of Pennsylvania Identification Test (UPSIT) [ Time Frame: Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention) — Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
  The UPSIT includes 4 odor-impregnated booklets that contain 10 forced-choice multiple choice questions each for participants to scratch-and-sniff to identify various odors and is a commercially available test. Normosmia is defined as ≥34 for males and ≥35 for females, and a change of 4 points or more from baseline indicates a clinically meaningful result.
• Changes from baseline in olfactory score on the Sniffin's Sticks test — Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
  Sniffin' Sticks test and Taste strips: Sniffin' Sticks test (Burghardt®, Wedel, Germany) is a psychophysical test. It allows semi-objective assessment of the patient's olfactory performance by means of 3 subtests: threshold test, identification test and discrimination test. The Sniffin' Sticks Olfactory Test Kits contain pen like bodies as, for example, in pens used to write on flipcharts or whiteboards.These pen-like bodies, however, contain a fibre stick which is filled with scents. For testing, the cap should be removed so the patient can smell on the tip of the pen.
• n-house test for chemosensory dysfunction (TMSC) — Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
  The TMSC is a 55-item questionnaire evaluating the three chemical senses: olfaction, taste and the trigeminal sense. First, questions with a 10-point visual analog scale make a subjective self-assessment of each of the three senses. Multiple-choice questions establish the precise characteristics of the dysfunctions of each of the senses if they are present. Secondly, a psychophysical test is administered remotely using substances typical of North American cuisines. Substances are first sniffed (peanut butter, jam, vinegar, coffee) then tasted (peanut butter, jam, salt water (1 tsp/250mL), sugar water (3 tsp/250mL)). The perceived intensity of each of the substances is reported each time on a visual analogue scale of 10 points.
• Parosmia and phantosmia assessment test — Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
  This test has a first part with four questions that aim to assess the presence of parosmia or phastosmia. Patients who have reported parosmia or phantosmia will be asked to complete a second part with six questions focusing on the quality of their olfactory distortion.
• The abridged version of the Questionnaire of Olfactory Disorders - Negative Statements (sQOD-NS) — Measurement will be taken at time zero (pre-intervention) and 12 weeks (post-intervention)
  The sQOD-NS is a validated questionnaire that measures the quality of life specific to olfactory functions. The questionnaire measures 7 items with a 4-point Likert scale.

Trial sites (1)

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