Multidimensional benefits of olfactory training for chronic COVID-19-related olfactory dysfunction: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of intervention studies
PubMed 40465208 · doi:10.4193/Rhin24.355
What was done
Authors performed a systematic review and meta-analysis searching Cochrane Library, Embase, PubMed, Scopus, and Web of Science up to February 24, 2024. They included studies evaluating olfactory training lasting over 8 weeks in patients with chronic COVID-19-related olfactory dysfunction lasting over 16 weeks.
What was found
Nine studies were included. Across 7 studies (179 patients) reporting Sniffin' Sticks data, olfactory training produced significant improvements in composite TDI score, threshold, discrimination, and identification subscores. Across 2 studies (63 patients) reporting UPSIT scores, and pooled identification tests overall, significant improvement was also found. No exact numerical effect sizes, confidence intervals, or p-values were reported in the abstract.
Why it matters
It indicates that structured olfactory training yields multidimensional recovery in chronic post-COVID-19 smell loss, spanning both peripheral sensitivity and higher-order odor identification.
Limits
The total sample size was small (179 patients for Sniffin' Sticks and 63 for UPSIT). The abstract omits numerical effect sizes, confidence intervals, control group details, and long-term durability of the improvement.