Predictive Value of Olfactory and Taste Symptoms in the Diagnosis of COVID-19: A Systematic Review and Meta-Analysis

Objectives. This study evaluated the diagnostic value of various symptoms of coronavirus disease 2019 (COVID-19) in screening for this disease. Methods. Two authors (working independently) comprehensively reviewed six databases (PubMed, Cochrane Database, Embase, Web of Science, Scopus, and Google Scholar) from their dates of inception until November 2020. The predictive value of patient-reported symptoms, including otolaryngologic and general symptoms, was evaluated in adults who underwent testing for COVID-19. True-positive, true-negative, false-positive, and false-negative data were extracted from each study. The methodological quality of the included studies was evaluated using the quality assessment of diagnostic accuracy studies tool (ver. 2). Results. Twenty-eight prospective and retrospective studies were included in the meta-analysis. The diagnostic odds ratio (DOR) of a change in olfaction and/or taste was 10.20 (95% confidence interval [CI], 8.43-12.34). The area under the summary receiver operating characteristic curve was 0.8. Olfactory and/or taste changes had a low sensitivity (0.57; 95% CI, 0.47-0.66) but moderate negative (0.78; 95% CI, 0.69-0.85] and positive (0.78; 95% CI, 0.66-0.87) predictive values and a high specificity (0.91; 95% CI, 0.83-0.96). Olfactory and/or taste changes had a higher diagnostic value than the other otolaryngologic symptoms, a higher DOR and specificity, and a similar or higher diagnostic value than the other general symptoms. Conclusion. Among otolaryngologic symptoms, olfactory and/or taste dysfunction was the most closely associated with COVID-19 and its general symptoms, and should therefore be considered when screening for the disease.

Automated summary

This study found that changes in olfaction and/or taste have a high diagnostic value in screening for COVID-19, particularly in terms of specificity. These symptoms have moderate positive and negative predictive values, which can help identify whether patients are likely to have COVID-19.