HealthDay News — Persistent COVID-19-related anosmia has an excellent prognosis with nearly complete recovery at one year, according to a research letter published online June 24 in JAMA Network Open.
Marion Renaud, M.D., from the University Hospitals of Strasbourg in France, and colleagues followed a cohort of patients with COVID-19-related anosmia at four-month intervals for one year and performed repeated olfactory function evaluations on some of the patients.
The researchers report that at four months, 23 of 51 patients reported full recovery of olfaction on subjective assessment, while 27 reported partial recovery and one reported no recovery. Based on psychophysical testing, 43 of 51 patients were objectively normosmic, including 19 of 27 who self-evaluated as only partially recovered. At eight months, six of the eight patients with persistent subjective or objective loss of smell became normosmic on objective testing, yielding full objective recovery in 49 of 51 patients. At one year, two patients remained hyposmic, with persistent abnormalities (one with abnormal olfactory threshold and one with parosmia causing abnormal identification). Among patients only undergoing subjective assessment, 13 of 46 patients reported satisfactory recovery at four months with the remaining 33 patients achieving it by 12 months (32 with total and 14 with partial recovery).
“Our findings suggest that an additional 10 percent gain in recovery can be expected at 12 months, compared with studies with six months of follow-up,” the authors write. “This supports findings from fundamental animal research, involving both imaging studies and postmortem pathology, suggesting that COVID-19-related anosmia is likely due to peripheral inflammation.”