Pilot study for immunoglobulin E as a prognostic biomarker in coronavirus disease 2019.

Background: Laboratory biomarkers to estimate the severity of coronavirus disease 2019 (COVID-19) are crucial during the pandemic since resource allocation must be carefully planned.

Aims: To evaluate the effects of basal serum total immunoglobulin E (IgE) levels and changes in inflammatory parameters on the clinical progression of patients hospitalised with COVID-19.

Methods: Patients hospitalised with confirmed COVID-19 were included in the study. Laboratory data and total IgE levels were measured on admission. Lymphocyte, eosinophil, ferritin, d-dimer and C-reactive protein parameters were recorded at baseline and on the 3rd and 14th days of hospitalisation.

Results: The study enrolled 202 patients, of which 102 (50.5%) were males. The average age was 50.17 ± 19.68 years. Of the COVID-19 patients, 41 (20.3%) showed clinical progression. Serum total IgE concentrations were markedly higher (172.90 (0-2124) vs 38.70 (0-912); P < 0.001) and serum eosinophil levels were significantly lower (0.015 (0-1.200) vs 0.040 (0-1.360); P = 0.002) in clinically worsened COVID-19 patients when compared with stable patients. The optimal cut-off for predicting clinical worsening was 105.2 ng/L, with 61% sensitivity, 82% specificity, 46.3% positive predictive value and 89.2% negative predictive value (area under the curve = 0.729). Multivariable analysis to define risk factors for disease progression identified higher total IgE and C-reactive protein levels as independent predictors.

Conclusions: Our single-centre pilot study determined that total IgE levels may be a negative prognostic factor for clinical progression in patients hospitalised due to COVID-19 infection. Future studies are required to determine the impact of individuals' underlying immune predispositions on outcomes of COVID-19 infections.