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Use of platelet-rich plasma for COVID-19 related olfactory loss, a randomized controlled trial. International forum of allergy & rhinology Yan, C. H., Jang, S. S., Lin, H. C., Ma, Y., Khanwalker, A. R., Thai, A., Patel, Z. M. 2022


This study evaluated the use of platelet-rich plasma (PRP), an autologous blood product with supraphysiologic concentrations of growth factors, in the treatment of prolonged COVID-19 related smell loss.This multi-institutional, randomized controlled trial recruited COVID-19 patients with objectively measured smell loss (University of Pennsylvania's Smell Identification Test, UPSIT=33) between 6-12 months. Subjects were randomized to 3 intranasal injections of either PRP or sterile saline into their olfactory clefts. Primary outcome measure was change in Sniffin' sticks score (TDI) from baseline. Secondary endpoint measures included responder rate (achievement of a clinically significant improvement, =5.5 point TDI), change in individual TDI olfaction scores, and change in subjective olfaction via a visual analogue scale.35 subjects were recruited and 26 completed the study. PRP treatment resulted in a 3.67 point (95% CI: 0.05-7.29, p = 0.047) greater improvement in olfaction compared to the placebo group at 3-months and a higher response rate (57.1% versus 8.3%, odds ratio 12.5, 95% exact bootstrap CI 2.2-116.7). There was a greater improvement in smell discrimination following PRP treatment compared to placebo, but no difference in smell identification or threshold. There was no difference in subjective scores between PRP and placebo. No adverse effects were reported.Olfactory function following COVID-19 can improve spontaneously after 6 months and can improve to a greater extent with PRP injection. This data builds on the promise of PRP to be a safe potential treatment option for patients with COVID-19 smell loss, and larger-powered studies will help further assess efficacy. This article is protected by copyright. All rights reserved.

View details for DOI 10.1002/alr.23116

View details for PubMedID 36507615