Methods
olfactory dysfunction
This double-blinded controlled, placebo-controlled multicenter randomized clinical trial was conducted in 202 patients with persistent COVID-19 olfactory dysfunction of > 6 month duration. After a screening nasal endoscopy, patients were randomized to: (1) olfactory training and placebo; (2) once daily um-PEA–LUT alone; (3) twice daily um-PEA–LUT alone; or (4) combination of once daily um-PEA–LUT with olfactory training. Olfactory testing (Sniffin’ Sticks odor identification test) was performed at baseline and at 1, 2, and 3 months. The primary outcome was recovery of over three points on olfactory testing, with outcomes compared at 