Recent Smell Loss Is the Best Predictor of COVID-19 Among Individuals With Recent Respiratory Symptoms

Citation

Gerkin RC, Ohla K, Veldhuizen MG, Joseph PV, Kelly CE, Bakke AJ, Steele KE, Farruggia MC, Pellegrino R, Pepino MY, Bouysset C, Soler GM, Pereda-Loth V, Dibattista M & Roberts SC (2021) Recent Smell Loss Is the Best Predictor of COVID-19 Among Individuals With Recent Respiratory Symptoms. Chemical Senses, 46, Art. No.: bjaa081. https://doi.org/10.1093/chemse/bjaa081

Abstract
In a preregistered, cross-sectional study, we investigated whether olfactory loss is a reliable predictor of COVID-19 using a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0–100 visual analog scales (VAS) for participants reporting a positive (C19+; n = 4148) or negative (C19−; n = 546) COVID-19 laboratory test outcome. Logistic regression models identified univariate and multivariate predictors of COVID-19 status and post-COVID-19 olfactory recovery. Both C19+ and C19− groups exhibited smell loss, but it was significantly larger in C19+ participants (mean ± SD, C19+: −82.5 ± 27.2 points; C19−: −59.8 ± 37.7). Smell loss during illness was the best predictor of COVID-19 in both univariate and multivariate models (ROC AUC = 0.72). Additional variables provide negligible model improvement. VAS ratings of smell loss were more predictive than binary chemosensory yes/no-questions or other cardinal symptoms (e.g., fever). Olfactory recovery within 40 days of respiratory symptom onset was reported for ~50% of participants and was best predicted by time since respiratory symptom onset. We find that quantified smell loss is the best predictor of COVID-19 amongst those with symptoms of respiratory illness. To aid clinicians and contact tracers in identifying individuals with a high likelihood of having COVID-19, we propose a novel 0–10 scale to screen for recent olfactory loss, the ODoR-19. We find that numeric ratings ≤2 indicate high odds of symptomatic COVID-19 (4 < OR < 10). Once independently validated, this tool could be deployed when viral lab tests are impractical or unavailable.

Keywords
anosmia; chemosensory; coronavirus; hyposmia; olfactory; prediction

Notes
Additional co-authors: Keiland W Cooper, Ilja Croijmans, Antonella Di Pizio, Mehmet Hakan Ozdener, Alexander W Fjaeldstad, Cailu Lin, Mari A Sandell, Preet B Singh, V Evelyn Brindha, Shannon B Olsson, Luis R Saraiva, Gaurav Ahuja, Mohammed K Alwashahi, Surabhi Bhutani, Anna D’Errico, Marco A Fornazieri, Jérôme Golebiowski, Liang Dar Hwang, Lina Öztürk, Eugeni Roura, Sara Spinelli, Katherine L Whitcroft, Farhoud Faraji, Florian Ph S Fischmeister, Thomas Heinbockel, Julien W Hsieh, Caroline Huart, Iordanis Konstantinidis, Anna Menini, Gabriella Morini, Jonas K Olofsson, Carl M Philpott, Denis Pierron, Vonnie D C Shields, Vera V Voznessenskaya, Javier Albayay, Aytug Altundag, Moustafa Bensafi, María Adelaida Bock, Orietta Calcinoni, William Fredborg, Christophe Laudamiel, Juyun Lim, Johan N Lundström, Alberto Macchi, Pablo Meyer, Shima T Moein, Enrique Santamaría, Debarka Sengupta, Paloma Rohlfs Dominguez, Hüseyin Yanik, Thomas Hummel, John E Hayes, Danielle R Reed, Masha Y Niv, Steven D Munger, Valentina Parma, GCCR Group Author

Journal
Chemical Senses: Volume 46