Correlations between IL-6 serum level and olfactory dysfunction severity in COVID-19 patients: a preliminary study
Luigi Angelo Vaira, Andrea De Vito, Giovanna Deiana, Chiara Pes, Federica Giovanditto, Vito Fiore, Jérôme R. Lechien, Serge‐Daniel Le Bon, Sven Saussez, Giordano Madeddu, Sergio Babudieri, Antonio Pazzola, Franco Bandiera, Alessandro Giuseppe Fois, Andrea Piana, Claire Hopkins, Giacomo De Riu
Abstract
Abstract Background Interleukin 6 (IL-6) is a proinflammatory cytokine that is secreted by cells infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and it is widely recognized as a negative prognostic factor. The purpose of this study was to analyze the correlations between the olfactory scores determined by psychophysical tests and the serum levels of IL-6 in patients affected by coronavirus disease 2019 (COVID-19) Methods Patients underwent psychophysical olfactory assessment with Connecticut Chemosensory Clinical Research Center test and IL-6 plasma level determination within 10 days of the clinical onset of COVID-19. Results Seventy-four COVID-19 patients were included in this study. COVID-19 staged as mild in 34 patients, moderate in 26 and severe in 14 cases. There were no significant differences in olfactory scores across the different COVID-19 severity groups. In the patient series, the median plasma level of IL-6 was 7.7 pg/mL (IQR 3.7–18.8). The concentration of IL-6 was found to be significantly correlated with the severity of COVID-19 with a directly proportional relationship. The correlation between IL-6 plasma concentrations and olfactory scores was weak ( r s = 0.182) and not significant ( p = 0.12). Conclusions In COVID-19 patients, psychophysical olfactory scores did not show significant correlations with the plasma levels of a well-recognized negative prognostic factor such as IL-6. This observation casts some shadows on the positive prognostic value of olfactory dysfunctions.