Prevalence of Olfactory Dysfunction in Coronavirus Disease 2019 (COVID‐19): A Meta‐analysis of 27,492 Patients

• Published in: The Laryngoscope 2021-04, Vol.131 (4), p.865-878
• Main Authors: Saniasiaya, Jeyasakthy, Islam, Md Asiful, Abdullah, Baharudin
• Format: Article
• Language: English
• Subjects: Coronavirus; COVID-19 - complications; COVID-19 - diagnosis; COVID‐19; Humans; Laryngoscopy; Meta-analysis; Olfaction disorders; Olfaction Disorders - diagnosis; Olfaction Disorders - epidemiology; Olfaction Disorders - virology; Olfaction‐Chemosensation; olfactory; Original Report; Prevalence; smell; Systematic review
• ISSN: 0023-852X; 1531-4995
• DOI: 10.1002/lary.29286

Objectives/Hypothesis Olfactory dysfunction has been observed as one of the clinical manifestations in COVID‐19 patients. We aimed to conduct a systematic review and meta‐analysis to estimate the overall pooled prevalence of olfactory dysfunction in COVID‐19 patients. Study Design Systematic review and meta‐analyses. Methods PubMed, Scopus, Web of Science, Embase, and Google Scholar databases were searched to identify studies published between 1 December 2019 and 23 July 2020. We used random‐effects model to estimate the pooled prevalence with 95% confidence intervals (CIs). Heterogeneity was assessed using the I2 statistic and Cochran's Q test. Robustness of the pooled estimates was checked by different subgroup and sensitivity analyses This study is registered with PROSPERO (CRD42020183768). Results We identified 1162 studies, of which 83 studies (n = 27492, 61.4% female) were included in the meta‐analysis. Overall, the pooled prevalence of olfactory dysfunction in COVID‐19 patients was 47.85% [95% CI: 41.20–54.50]. We observed olfactory dysfunction in 54.40% European, 51.11% North American, 31.39% Asian, and 10.71% Australian COVID‐19 patients. Anosmia, hyposmia, and dysosmia were observed in 35.39%, 36.15%, and 2.53% of the patients, respectively. There were discrepancies in the results of studies with objective (higher prevalence) versus subjective (lower prevalence) evaluations. The discrepancy might be due to false‐negative reporting observed in self‐reported health measures. Conclusions The prevalence of olfactory dysfunction in COVID‐19 patients was found to be 47.85% based on high‐quality evidence. Due to the subjective measures of most studies pooled in the analysis, further studies with objective measures are advocated to confirm the finding. Level of Evidence 2 Laryngoscope, 131:865–878, 2021