WEDNESDAY, Jan. 6, 2021 (HealthDay News) -- The majority of patients with mild COVID-19 versus patients with moderate-to-critical forms report loss of smell, with 75 to 85 percent of all patients recovering olfaction at two months after infection, according to a study published online Jan. 6 in the Journal of Internal Medicine.
Jerome R. Lechien, M.D., Ph.D., from the University of Mons in Belgium, and colleagues investigated the prevalence of and recovery from olfactory dysfunction (OD) in COVID-19 patients according to disease severity. The analysis included 2,581 COVID-19 patients identified from 18 European hospitals (March 22 to June 3, 2020) and followed for two months after infection; 1,363 patients with OD completed evaluations.
The researchers found that the prevalence of OD was significantly higher in mild forms of COVID-19 (85.9 percent) versus moderate-to-critical forms of the disease (4.5 to 6.9 percent). Nearly one-quarter of patients with OD (24.1 percent) did not subjectively recover olfaction at 60-day follow-up. Self-reported OD lasted a mean of 21.6 days. On objective olfactory evaluation, hyposmia/anosmia occurred in 54.7 percent of patients with mild forms of COVID-19, while 36.6 percent of patients with moderate-to-critical forms of the disease experienced hyposmia/anosmia. Among anosmic/hyposmic patients, at 60 days and six months, 15.3 and 4.7 percent, respectively, did not objectively recover olfaction. Higher baseline severity of objective olfactory evaluations strongly predicted persistent OD.
"Considering both subjective and objective data, we may suggest that the 60-day recovery rate ranges from 75 percent to 85 percent," the authors write.