Correlations between IL-6 serum level and olfactory dysfunction severity in COVID-19 patients: a preliminary study

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 (rs = 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.

Predictive factors of smell recovery in a clinical series of 288 coronavirus disease 2019 patients with olfactory dysfunction

“…However, no clinical, epidemiological or laboratory risk factors have yet been identified [32,33]. In this study including 288 patients with COVID-19 OD, it is confirmed that no clinical or epidemiological factor predicts the evolution of OD at 2 months.…”

The Effects of Persistent Olfactory and Gustatory Dysfunctions on Quality of Life in Long-COVID-19 Patients

“…It has not yet been clarified what the frequency of persistent disturbances is in these groups of individuals, but if the prevalence recorded in cases of primary infection were confirmed, it would mean that this problem may not end with the immunization of the population. Second, the identification of the pathogenesis [54][55][56][57][58][59][60][61] and risk factors [2][3][4][5][6][7][8][9][10][11][12][62][63][64][65][66][67][68] for the development of persistent CD are in its infancy. For this reason, no effective therapies have yet been found for the prevention and treatment of COVID-19 related POD and PGD [69][70][71][72][73][74][75].…”

IL-6 serum level and olfactory dysfunction severity in COVID-19: correspondence

“…Dear Editor, we would like to comment on the publication “Correlations between IL-6 serum level and olfactory dysfunction severity in COVID-19 patients: a preliminary study [ 1 ].” Vaira et al concluded that “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.…”

“…This observation casts some shadows on the positive prognostic value of olfactory dysfunctions. [ 1 ].” We agree that it is interesting to try to find clinical correlation between olfactory symptom and a laboratory parameter for inflammation. Regarding IL-6, it is an inflammatory marker and might be associated with many confounding factors.…”