Olfactory Training for Postviral Olfactory Dysfunction: Systematic Review and Meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of controlled trials
PubMed 32660334 · doi:10.1177/0194599820943550
What was done
Authors conducted a systematic review and meta-analysis following PRISMA guidelines querying PubMed, Embase, and Web of Science. They assessed the efficacy of olfactory training (OT) specifically for postviral olfactory dysfunction (PVOD), excluding studies evaluating pharmacologic interventions or olfactory loss from non-viral causes.
What was found
From 1,981 abstracts, 16 full-text articles were included. Fifteen studies (93%) measured outcomes using Sniffin' Sticks threshold, discrimination, and identification (TDI) scores. All 16 studies reported clinically significant improvements (TDI change >5.5) after OT. In a meta-analysis of 4 studies with control groups, patients receiving OT had higher odds of achieving a clinically important difference in TDI scores compared to controls (odds ratio 2.77, 95% CI 1.67-4.58).
Why it matters
This study provides pooled quantitative evidence supporting the use of olfactory training as an effective non-pharmacological therapy for smell loss following viral infections.
Limits
Only 4 of the 16 studies were eligible for meta-analysis, the total participant sample size was not reported in the abstract, the specific design of individual included studies (randomized vs observational controls) was not stated, and olfactory training protocols varied across studies.
Cited by
- supports Smell training protocols involving repeated deliberate sniffing of specific odors can improve olfactory acuity and assist recovery after olfactory loss or injury.