Endocan as a potential marker in diagnosis and predicting disease severity in COVID-19 patients: a promising biomarker for patients with false-negative RT-PCR.

Background: Endothelial-specific molecule 1 (endocan) has emerged as an inflammatory biomarker in recent years. The purpose of this study was to investigate the diagnostic value of serum endocan levels in the prediction of COVID-19 disease among patients with a false-negative reverse transcription polymerase change reaction (RT-PCR) test, and also to determine its correlation with the clinical severity of the disease.

Methods: Thirty patients with positive RT-PCR results and 30 with false-negative RT-PCR results, both with suspected COVID-19 in terms of clinical, radiological, and laboratory findings, were included in the study. Thirty healthy controls were also enrolled.

Results: Serum endocan levels were estimated to be 821.8 ± 99.3 pg/mL in COVID-19 RT-PCR (+) patients, 803.9 ± 97.0 pg/mL in RT-PCR false (-) patients with suspected COVID-19, and 382.9 ± 37.5 pg/mL in the control group. No significant difference was observed between RT-PCR (+) and RT-PCR false (-) patients (P = 0.68). However, serum endocan levels differed significantly between patient groups and control group (P < 0.05). With a cut-off value of 444.2 pg/mL serum endocan levels differentiated COVID-19 cases from healthy individuals with 92% sensitivity and 80% specificity. Moreover, a significant positive correlation was observed between serum endocan levels and clinical severity (P < 0.01, r = 0.94).

Conclusions: There is a need for different laboratory markers capable of assisting diagnosis and showing COVID-19 infection in suspected COVID-19 RT-PCR false-negative patients. Endocan levels can be used as an assistant blood test for identifying COVID-19 patients with false-negative RT-PCR tests and in determining the clinical severity of the disease.