Evaluation of the Association Between Ct Value of SARS-CoV-2 PCR with Disease Progression and Mortality

Objective: Multiple factors have been studied in association with disease severity in COVID-19. The cycle threshold (Ct) value of polymerase chain reaction (PCR) can reflect viral load in the specimens. In this study, we aimed to evaluate the effect of the Ct value on clinical course and mortality in COVID-19 patients. Methods: Adult patients who tested positive for SARS-CoV-2 with PCR test and who were hospitalized with COVID-19-related symptoms between August 1, 2020, and November 30, 2020, were included in the study. In addition, Ct value, demographic and clinical data (length of hospital stay, need for admission to intensive care unit (ICU), need for mechanical ventilation (MV), and mortality) were reviewed retrospectively. Results: 117 patients were included in the study. The mean Ct value was 22.37±4.72 (11.07-34.06). There was no significant difference in the mean Ct values between the patients who needed ICU admission and those who did not. When the patients were evaluated by dividing them into three groups according to their Ct values, as < 20, between 20-24 and >24; there was no significant difference between these three groups in terms of severity of pneumonia, laboratory parameters (D-dimer, Neutrophil/Lymphocyte ratio, C-reactive protein, lymphocyte count), length of hospital stay, need for ICU admission, need for MV and mortality. When the patients were divided into two groups with Ct values as <23.3 and ≥23.3, no significant difference was found between the groups regarding ICU need, MV need, and 28-day mortality rates. Conclusion: Most of the studies in the literature about Ct value and its effect on clinical course indicate that lower Ct values are potentially associated with worse outcomes in COVID-19. However, there are also studies reporting that the Ct value does not reflect the severity of the disease. We did not find a correlation between Ct value and laboratory markers, length of hospital stay, the severity of pneumonia, need for ICU admission or MV, and mortality in COVID-19 patients in this presented study. Keywords: Ct value, cycle threshold, COVID-19, clinical course, mortality