Olfactory and gustatory dysfunctions in COVID-19 patients: A systematic review and meta-analysis

Olfactory and gustatory dysfunctions (OGD) are pathognomonic symptoms in patients with Coronavirus Disease 2019 (COVID-19). This study reviews the associations of OGD with COVID-19 which will be useful for early diagnosis and self-isolation. Systematic searches of PubMed, Ovid Medline, Scopus, and EMBASE electronic databases were performed. Studies reporting OGD in COVID-19 patients were included. Data were pooled for meta-analysis. The outcomes were odds ratios (OR) of OGD in COVID-19 patients. Proportions of smell and/or taste dysfunctions in the COVID-19 patients were assessed. Fourteen studies (21,515 participants, age 49.12 years, 26% male) were included. The OR of olfactory and/or gustatory dysfunctions in COVID-19 patients were 11.26 (95% confidence interval (CI) 5.41 to 23.4) when compared with acute respiratory infection (ARI) without detectable virus and 6.46 (95% CI 2.79 to 14.97) in patients with other respiratory viruses. The OR of olfactory dysfunction in COVID-19 patients were 11.67 (95% CI 6.43 to 21.17) when compared with the ARI patients without detectable virus and 4.17 (95% CI 1.34 to 12.98) with other respiratory viruses. The OR of gustatory dysfunction in COVID-19 patients were 12.70 (95% CI 7.9 to 20.44) when compared with the ARI patients without detectable virus and 4.94 (95%CI 1.59 to 15.31) with other respiratory viruses. Fifty percent (95% CI 36.7 to 63.3%) of COVID-19 patients had olfactory and/or gustatory dysfunctions. In summary, there are associations between OGD and COVID-19 patients. Patients presenting with ARI should be assessed for olfactory and gustatory functions.