Olfactory and Gustatory Recovery Time Evaluation of COVID-19: A Systematic Review and Meta-Analysis.
Background: Olfactory dysfunction is a common symptom of Coronavirus disease 2019 (COVID-19). In this study, we aimed to evaluate the recovery rate and duration of these symptoms in COVID-19patients.
Methods: This systematic review was conducted by searching PubMed and Google Scholar from April 1st, 2020, until October 1st, 2022, using the terms ''COVID-19'' OR ''COV-2,'' OR ''Coronavirus 2'' OR coronavirus AND ''loss of smell'' OR Anosmia OR Hyposmia OR olfaction OR ''olfactory loss'' AND ageusia OR Hypogeusia OR dysgeusia OR ''gustatory loss'' OR gustation OR ''loss of taste''. The references of included studies were also manually screened. Random-effects meta-analysis was performed.
Results: One hundred and twenty-five studies with test-confirmed COVID-19 infection from 31 countries were included. 62 publications which reported data on loss of taste were used to estimate patients' recovery rate in 13700 COVID-19 patients. Accordingly, the time to recovery of loss of taste among COVID-19 patients ranged from 2±0.352 to 43.6 ± 28.5 days. The estimated overall pooled recovery rate of loss of taste among COVID-19 patients was 74%. The estimated overall pooled time to recover loss of taste among COVID-19 patients was 11.44 days [95% CI 8.11, 14.77(]. 90 publications which reported data on loss of smell were used to estimate patients' recovery rate in 20027 COVID-19 patients. Accordingly, the time to recover the loss of smell among COVID-19 patients ranged from 2.44±0.352 to 31.9 ± 30.7 days The estimated overall pooled recovery rate of loss of smell among COVID-19 patients was 72%. The estimated overall pooled time to recover loss of smell among COVID-19 patients was 12.87 days [95% CI)1011, 15.64(].
Conclusions: The recovery rate of loss of smell and taste among COVID-19 patients was high globally, and time to recovery of loss of smell and taste among COVID-19 patients usually was less than 2 weeks; regional differences supported the relevance of these symptoms as important markers. Health workers must consider smell and taste symptoms as suspicion indices for the empirical diagnosis of COVID-19 infection and reassure patients with their high recovery rate in a short period of time.