Chest computed tomography score, cycle threshold values and secondary infection in predicting COVID-19 mortality

This retrospective and observational cohort study investigated chest computed tomography (CT) findings, cycle threshold (Ct) values in RT-PCR of SARS-CoV-2 and secondary infection occurrence to predict prognosis in COVID-19 patients. At hospital admission, CT findings and Ct values were collected. Microbiology tests performed after 48 hours from hospitalization were reviewed. According to in-hospital mortality, patients were grouped into non-survivors and survivors. Among 283 patients evaluated, in-hospital mortality rate was 13.8% (39/283). Secondary infection occurrence was 15.2% (43/283). Cut-off values for CT score >13.5 (AUC=0.682 p=0.0009) and for Ct <23.4 (AUC=0.749, p<0.0001) were predictive of death. Super-additive and synergic effects between high CT score plus secondary infection occurrence as well as between high CT score plus low Ct values affecting patient's outcome were observed. Chest CT score and Ct values in RT-PCR of SARS-CoV-2 could have a combination role for severity stratification of COVID-19 patients.