Self-reported loss of smell without nasal obstruction to identify COVID-19. The multicenter CORANOSMIA cohort study

J Infect. 2020 Jul 7;S0163-4453(20)30463-1. doi: 10.1016/j.jinf.2020.07.005. Online ahead of print.

Abstract

Objectives: To determine the frequency of SARS-CoV-2 positive samples in a subset of patients consulting for primarily isolated acute (<7 days) loss of smell and to assess the diagnostic accuracy of olfactory/gustatory dysfunction for COVID-19 diagnosis in the overall population tested for COVID-19 in the same period.

Methods: Prospective multicentric cohort study in four olfactory ENT units and a screening center for COVID-19.

Results: i) Among a subset of 55 patients consulting for primarily loss of smell, we found that 51 (92.7%) had a COVID-19 positive test (median viral load of 28.8 cycle threshold). Loss of smell was mostly total (anosmia), rarely associated with nasal obstruction but associated with a taste disorder in 80%. Olfactory dysfunction occurred suddenly, either as first complaint. The majority of patients (72.9%) partially recovered the sense of smell within 15 days. ii) In a population of 1824 patients tested for COVID-19, the positive predictive value and the specificity of loss of smell and/or taste were 78.5% and 90.3% respectively (sensitivity (40.8%), negative predictive value (63.6%)).

Conclusions: Self-reported loss of smell had a high predictive positive value to identify COVID-19. Making this sign well known publicly could help to adopt isolation measures and inform potential contacts.

Keywords: Anosmia; COVID-19; Dysgueusia; Loss of smell; Positive predictive value; SARS-COV-2; Viral load.