In a study executed by UMC Utrecht it was demonstrated that after prednisolone does not improve sense of smell after COVID-19. In addition, in most patients – irrespective of prednisolone use - sense of smell gradually improved over time. The authors recommend not to prescribe prednisolone for patients with persistent smell and/or taste disorders after COVID-19.

During the corona pandemic, more and more people noticed that they could not smell or taste after having been infected with the SARS-CoV-2 virus. As the persistent loss of smell is thought to be caused by an inflammatory response, corticosteroids might be a treatment option. Therefore, researchers from several universities and hospitals started last year a large randomized, double-blind study to investigate the possible role of prednisolone to improve loss of smell and taste due to COVID-19. This drug has been suggested as a treatment for olfactory disorders after COVID-19, but evidence on its efficacy is scarce. This week, the results of the study were published in BMC Medicine.

No improvement with prednisolone

"The results of our study in 115 patients show that after 3 months of treatment there is no greater improvement in the sense of smell in patients who were on prednisolone (40 mg/day for 10 days, starting at least 4 weeks after infection) as compared to those who received a placebo”, says ear-nose-throat surgeon Digna Kamalski from UMC Utrecht, who coordinated the study. "We did see that the sense of smell of both groups of patients continued to improve, even long after the corona infection has occurred. That, of course, is good news."

Smell function recovers by itself

In the ZonMW-funded research project "Sniffing out COVID," several studies are underway, including the course of loss of smell and taste as a result of COVID-19 and whether smell and taste recover on their own and to what extent. Now that the results of this study are known, there will be a follow-up. Digna: "We have invited all patients to be tested again after 1 year, as we are very interested to know whether or not the improvement persists."

Olfactory disorders after COVID-19

Olfactory disorders (dysfunction of smell) are a common early feature in COVID-19, occurring in about two of every three patients. Although most patients recover within 4 weeks, it is reported that up to 46 percent of patients still have impaired smell after 6 months and 20–60 percent after a year. The prevalence of long-term olfactory disorders varies widely because of the different methods of assessing olfactory function and a lack of follow-up. Patients with persistent olfactory disorders are at increased risk of having depressive symptoms and nutritional issues, both decreasing quality of life.

Collaboration

The study was conducted by a team of scientists and experts from the Department of Ear, Nose and Throat Surgery at UMC Utrecht, Wageningen University & Research, the Smell and Taste Center of Hospital Gelderse Vallei and patient association www.reuksmaakstoornis.nl.

Publication

Schepens EJA, Blijleven EE, Boek WM, Boesveldt S, Stokroos RJ, Stegeman I, Kamalski DMA. Prednisolone does not improve olfactory function after COVID-19; a randomized, double-blind, placebo-controlled trial. BMC Medicine 2022;20:445