Correlation of Real-Time PCR Cycle Threshold Values and Clinical Progress, Mortality, and Laboratory Parameters of COVID-19 Patients

Objective: The cycle threshold value was used to predict disease severity, disease progression, determine transmissibility, and differentiate active viral replication from prolonged virus shedding. In this study, we aimed to evaluate the relationship between rRT-PCR cycle threshold and clinical course, mortality and laboratory parameters in COVID-19 patients. Methods: The patients included in the study were grouped according to how they were followed; as outpatients, service and intensive care unit patients. Data of age, gender, length of hospital stay, survival status and comorbidities of the patients were obtained from the hospital information system. In addition, CRP, ferritin, albumin, lactate dehydrogenase, procalcitonin and iron values of inpatients were reviewed retrospectively. Cycle threshold values of the patients were compared with each parameter separately. Results: 1339 patients with positive SARS-CoV-2 rRT-PCR test were included in the study. Of the patients, 774 (58%) were outpatients, 548 (41%) were in the ward, and 17 (1%) were in the intensive care unit. No significant difference was found between any of the groups when the cycle threshold values of the groups were compared statistically. Fifty (3.7%) of the patients included in the study died. Cycle threshold values of deceased patients were found to be significantly lower than those who survived (p=0.019). 306 (22.8%) of the patients had comorbidities. When the cycle threshold values of patients with and without comorbid disease were compared, no significant difference was found between any of the groups (p=0.850). In addition, no significant correlation was found between the length of hospital stay, age, CRP, LDH, ferritin, procalcitonin, albumin and iron values and the cycle threshold value. Conclusion: In conclusion, we did not find a significant difference between the cycle threshold values of outpatients, ward patients and intensive care patients. No significant correlation was found between the laboratory parameters, length of hospital stay and age, and the cycle threshold: however, deceased patients were found to have lower cycle thresholds than surviving patients.