Almost all COVID-19 patients have diminished sense of smell

Quantitative smell testing shows that decreased smell function is a major marker for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, according to a study published online April 17 in the International Forum of Allergy & Rhinology.

Shima T. Moein, M.D., Ph.D., from the Institute for Research in Fundamental Sciences in Tehran, Iran, and colleagues administered the University of Pennsylvania Smell Identification Test (UPSIT), a validated 40-odorant test, to 60 confirmed COVID-19 inpatients and 60 age- and sex-matched controls to evaluate the magnitude and frequency of their olfactory dysfunction.

The researchers found that 98 percent of the COVID-19 patients exhibited some smell dysfunction (mean UPSIT score, 20.98 versus 34.10 in controls; P < 0.0001). More than half of the patients (58 percent) were anosmic (25 percent) or severely microsmic (33 percent), while 27 percent exhibited moderate microsmia and 13 percent mild microsmia. Only one patient (2 percent) showed normosmia. Patients showed deficits on all 40 UPSIT odorants. The researchers found no significant associations between test scores and sex, disease severity, or comorbidities.

"Quantitative smell testing demonstrates that decreased smell function, but not always anosmia, is a major marker for SARS-CoV-2 infection and suggests the possibility that smell testing may help, in some cases, to identify COVID-19 patients in need of early treatment or quarantine," conclude the authors.

One author reports financial ties to the pharmaceutical and medical device industry, including Sensonics International, the manufacturer and distributor of the smell test used in the study.

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