Predictive value of sudden olfactory loss in the diagnosis of COVID-19

  1. Antje Haehner
  2. Julia Draf
  3. Sarah Dräger
  4. Katja de With
  5. Thomas Hummel

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Abstract

Introduction

Recent reports suggest that sudden smell loss might be a symptom of SARS-CoV-2 infection. The aim of this study was to investigate the frequency of olfactory loss in an out-patient population who presented to a coronavirus testing center during a 2-week period and to evaluate the diagnostic value of the symptom “sudden smell loss” for screening procedures.

Methods

In this cross-sectional controlled cohort study, 500 patients who presented with symptoms of a common cold to a corona testing center and fulfilled corona testing criteria, completed a standardized diagnostic questionnaire which included the patients’ main symptoms, time course and an additional self-assessment of the patients’ current smell, taste function and nasal breathing compared to the level before onset of symptoms.

Results

Out of the 500 patients, 69 presented with olfactory loss. Twenty-two of them subsequently tested positive for SARS-CoV-2. Only twelve out of the patients without olfactory loss tested positive, resulting in a frequency of 64.7% for the symptom “sudden smell loss” in COVID-19 patients. Compared to COVID-19 patients without smell loss, they were significantly younger and less severely affected. Changes in nasal airflow were significantly more pronounced in SARS-CoV-2 negative patients with olfactory complaints compared to the patients with smell loss who were tested positive for SARS-CoV-2. By excluding patients with a blocked nose, the symptom “sudden smell loss” can be attested a high specificity (97%) and a sensitivity of 65% with a PPV of 63% and NPV of 97% for COVID-19.

Conclusion

Considering the high frequency of smell loss in non-hospitalized COVID-19 patients, acute olfactory impairment should be included in the WHO symptoms list and should be recognized as an early symptom of the disease. In contrast to other acute viral smell impairment, COVID-19 associated smell loss seems to be only rarely accompanied by a severely blocked nose.

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  1. ScreenIT

    SciScore for 10.1101/2020.04.27.20081356: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    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.

    About SciScore

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  2. Version published to 10.1101/2020.04.27.20081356v1 on medRxiv
  3. Version published to 10.1159/000509143