RT-PCR cycle threshold (Ct) values predicting COVID-19 patients' outcome

Aim: Clinical presentation of COVID-19 ranges from asymptomatic to fatal cases. Therefore, predictability of prognosis gains importance in managing the disease. The aim of this study is to investigate the relation between RT-PCR cycle threshold (Ct) values and the clinical severity of COVID-19 infection. Material and Methods: A retrospective study was conducted among 1224 COVID-19 patients. A scoring system, which is designed by the World Health Organization was used to classify patients by means of their clinical status. Results: The cut-off for Ct value in ROC curves was 21.52 at the point, when the COVID-19 patient clinic is shifting from ambulatory to hospitalized (79.7% sensitivity, 69% specificity). A significant weak positive correlation was found between age and WHO Score (r= .238 p<0.01) and a significant weak negative correlation was found between Ct value and WHO Score (r=-.068 p<0.05) in COVID-19 patients. Discussion: Patients with lower RT-PCR Ct values were more likely to go through the disease more severely due to higher virulence. Reporting of numerical Ct values may help clinicians in terms of prognosis.