Objective sensory testing methods reveal a higher prevalence of olfactory loss in COVID-19–positive patients compared to subjective methods: A systematic review and meta-analysis
This article has been Reviewed by the following groups
Listed in
- Evaluated articles (ScreenIT)
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has currently infected over 6.5 million people worldwide. In response to the pandemic, numerous studies have tried to identify causes and symptoms of the disease. Emerging evidence supports recently acquired anosmia (complete loss of smell) and hyposmia (partial loss of smell) as symptoms of COVID-19, but studies of olfactory dysfunction show a wide range of prevalence, from 5% to 98%. We undertook a search of Pubmed/Medline and Google Scholar with the keywords “COVID-19,” “smell,” and/or “olfaction.” We included any study that quantified smell loss (anosmia and hyposmia) as a symptom of COVID-19. Studies were grouped and compared based on the type of method used to measure smell loss—subjective measures such as self-reported smell loss versus objective measures using rated stimuli—to determine if prevalence differed by method type. For each study, 95% confidence intervals (CIs) were calculated from point estimates of olfactory disturbances. We identified 34 articles quantifying anosmia as a symptom of COVID-19 (6 objective, 28 subjective), collected from cases identified from January 16 to April 30, 2020. The pooled prevalence estimate of smell loss was 77% when assessed through objective measurements (95% CI of 61.4-89.2%) and 44% with subjective measurements (95% CI of 32.2-57.0%). Objective measures are a more sensitive method to identify smell loss as a result of infection with SARS-CoV-2; the use of subjective measures, while expedient during the early stages of the pandemic, underestimates the true prevalence of smell loss.
Article activity feed
-
-
SciScore for 10.1101/2020.07.04.20145870: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
Software and Algorithms Sentences Resources First, Pubmed/Medline and Google Scholar were used to retrieve literature with the keyword “COVID-19” plus “smell” and/or “olfaction” on May 15, 2020, and manual search of relevant articles via Google Scholar was also performed on June 4, 2020, yielding a total of 78 articles. Pubmed/Medlinesuggested: NoneGoogle Scholarsuggested: (Google Scholar, RRID:SCR_008878)Heterogeneity was assessed using Cochran’s Q and I2. Cochran’ssuggested: NoneResults from OddPub: Thank you for …
SciScore for 10.1101/2020.07.04.20145870: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
Software and Algorithms Sentences Resources First, Pubmed/Medline and Google Scholar were used to retrieve literature with the keyword “COVID-19” plus “smell” and/or “olfaction” on May 15, 2020, and manual search of relevant articles via Google Scholar was also performed on June 4, 2020, yielding a total of 78 articles. Pubmed/Medlinesuggested: NoneGoogle Scholarsuggested: (Google Scholar, RRID:SCR_008878)Heterogeneity was assessed using Cochran’s Q and I2. Cochran’ssuggested: NoneResults from OddPub: Thank you for sharing your code and data.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Limitations and Future Research: Due to the nature of data collection amidst an evolving global pandemic, there are inherent limitations to the present meta-analysis, many of which were driving factors of the observed high heterogeneity across studies. Disease severity of the recruited study population (COVID-19–positive patients) was not controlled for, which could add to selection bias. A wide range of measurement methods were employed within both objective and subjective categories, which naturally creates measurement bias. Often recall bias occurs in subjective methodologies, as self-recognition may occur only in severe cases and is often forgotten in prolonged, more subtle cases (47). Furthermore, there is lack of awareness regarding chemosensory function in subjects—many researchers combined the “loss of taste or smell” in their symptomatic findings, even though they are two completely different perceptions that would be impacted differently by SARS-CoV-2. In addition, there remains a lack of comprehensive testing of chemesthetic sensations (e.g., burn from capsaicin or cooling from menthol compounds) (50). Assessment of olfactory function in patients with suspected or confirmed COVID-19 diagnosis may become standard practice by clinicians. Despite the limitations inherit in subjective measures, at a minimum, patients need to be interviewed about their sense of smell as a first-line assessment. Given the interrelationship between smell and taste, during clinical assessm...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
-
