LANDMARK: Olfactory retraining efficacy – Systematic Review

Pekala K, Chandra RK, Turner JH. Efficacy of olfactory training in patients with olfactory loss: a systematic review and meta-analysis. Int Forum Allergy Rhinol. 2016;6(3):299-307.

  • A systematic review and meta-analysis looking at studies that included patients with olfactory dysfunction who had olfactory training. 10 studies with 639 patients were included in this review that met criteria.
  • Olfactory dysfunction was due to multiple etiologies in these studies.
  • Most studies used the Threshold, Discrimination and Identification (TDI) score as the primary endpoint with >5.5 or 6 considered significant improvement in most. Most studies did not separate etiology of smell loss.
  • Patients who went through olfactory training had a statistically significant improvement in TDI score compared to control groups. Olfactory training in these studies showed improvement in discrimination and identification but not thresholds.
  • There was a statistically significant difference in the olfactory training group compared to controls when looking at clinically significant improvement of TDI score (greater than 5.5 or 6 points based on the study).