Smell dysfunction in COVID-19 patients: More than a yes-no question

• Published in: Journal of the neurological sciences Vol. 418; p. 117107
• Main Authors: Lima, Marco A., Silva, Marcus Tulius T., Oliveira, Raquel V., Soares, Cristiane N., Takano, Crissi L., Azevedo, Anna E., Moraes, Raissa L., Rezende, Rafaela B., Chagas, Ingrid T., Espíndola, Otávio, Leite, Ana Claudia, Araujo, Abelardo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.11.2020
• Subjects: Adult; Anosmia - diagnosis; Anosmia - epidemiology; Anosmia - physiopathology; Brazil - epidemiology; Case-Control Studies; Central nervous system viral diseases; Clinical Short Communication; Comorbidity; COVID-19; COVID-19 - epidemiology; COVID-19 - physiopathology; Female; Humans; Male; Olfaction disorders; Pandemics; Predictive Value of Tests; Prevalence; SARS-CoV-2 - pathogenicity; Smell - physiology; Brazil; COVID-19; Olfaction disorders; Central nervous system viral diseases
• ISSN: 0022-510X; 1878-5883
• DOI: 10.1016/j.jns.2020.117107

Anosmia has been recognized as a prevalent and early symptom by many COVID-19 patients. However, most researchers have recorded smell dysfunction solely as present or absent and based on subjective evaluation by patients. We described the results of 57 consecutive COVID-19 patients seen at FIOCRUZ, Rio de Janeiro, Brazil, from April to May 2020. Data about the presence of smell loss, the onset of smell loss and other COVID-19 symptoms such as ageusia and nasal congestion or rhinorrhea were recorded. All patients at the initial consultation and 34 healthy controls underwent the Q-SIT, which is a quick disposable three-item smell identification test, by a trained physician. We compared three groups: healthy controls, COVID+ patients with reported smell loss (COVID w/ SL) and COVID+ patients without smell loss (COVID+ w/o SL). The mean age of patients was 41.4 years (SD ± 10.4), and 54.4% were women. Smell loss was reported by 40.4% of COVID-19 patients. We observed a gradual effect with higher Q-SIT scores in healthy controls, followed by COVID+ w/o SL and COVID+ w/ SL (medians = 3, 2 and 0; respectively, p < 0.001). Anosmia or severe microsmia (Q-SIT≤1) was present in 11.1% (CI: 3.1%–26.1%) of controls, 32.4% (CI: 17.4%–50.5%) of COVID-19 w/o SL and 87% (CI: 66.4%–97.2%) of COVID+ w/ SL (p < 0.001). This study provides evidence that olfactory dysfunction in COVID-19 is common and more prevalent than what is perceived by patients. Q-SIT is a quick and reliable screening test for the detection of smell dysfunction during the pandemics. •Smell dysfunction is frequent in COVID-19 patients.•Subtle olfactory dysfunction is frequently not perceived by patients when inquired during medical visits.•Q-SIT is a quick and reliable screening test for the detection of smell dysfunction during the pandemics.