Efficacy of Platelet-Rich Plasma in the Treatment of Persistent Olfactory Impairment After COVID-19: A Systematic Review and Meta-Analysis.

Background And Objectives: This study aimed to evaluate the impact of topical platelet-rich plasma (PRP) injection on persistent refractory olfactory dysfunction after COVID-19 infection.

Methods: A systematic review was conducted, focusing on studies that compared the efficacy of topical PRP treatment with a control group (receiving either placebo or no treatment) in ameliorating olfactory dysfunction. Pre- and post-treatment comparisons were evaluated, along with a subgroup analysis of olfactory function evaluation.

Results: The analysis revealed a significant improvement in olfactory scores between 1 to 3 months post-treatment (standardized mean difference=1.4376; 95% confidence interval [CI]=0.5934-2.2818; I=84.1%) in the treatment group compared to the control group. Moreover, a notable disparity was observed between the two groups in the incidence of substantial recovery from anosmia or hyposmia (odds ratio=8.6639; 95% CI=2.9752-25.2292; I=0.0%). PRP treatment led to a clinically significant increase in the threshold, discrimination, and identification (TDI) score for the Sniffin' Sticks test by >5.5 (minimum clinically significant difference; mean difference, 6.3494; 95% CI=4.0605-8.6384; I=0.0%), as confirmed by verified examinations. The odds ratio for significant improvement among patients after treatment was determined to be 0.7654 (95% CI=0.6612-0.8451). Furthermore, all TDI subdomains exhibited significant and comparable improvements post-treatment.

Conclusion: This meta-analysis indicates that the injection of PRP into the olfactory fissure or surrounding mucosal areas is an effective treatment for persistent refractory olfactory dysfunction.