Importance of cycle threshold values in detection of severity and outcome in patients with severe acute respiratory syndrome coronavirus 2

Background and Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) is a highly transmissible and pathogenic coronavirus that emerged in late 2019. Cycle threshold (Ct) value of real-time reverse transcription polymerase chain reaction (RT-PCR) assay inversely correlated with viral load and can provide an indirect method of quantifying the number of copies of viral RNA in the sample is not reported clinically. Hence, this study was undertaken to compare the Ct values of patients tested positive for SARS CoV-2 by RT-PCR with severity of illness, duration of hospital stay, and mortality. Materials and Methods: A retrospective study was conducted over a period of 6 months in a tertiary care hospital in Bangalore. All patients tested positive for SARS CoV-2 by RT-PCR and admitted in our hospital were included in the study. Details of the patients on the duration of hospital stay, age, presence of comorbidities, intubation, and mortality were collected. Results: The study comprised of 80 patients, 48 (60%) males and 32 (40%) females. The mean age of the study population was 38.38 years. Majority of patients 41.25% had Ct value between 25 and 30. Patients with lower Ct values were significant associated with increased duration of hospital stay and infected more than one person in family indicating higher probability of transmission of infection. Mortality showed significant association with patients of more than 60 years' age. Interpretation and Conclusions: The study shows possible association between Ct values of SARS-CoV-2 RT-PCR assay with the duration of hospitalization, infectivity, and mortality. Mention of Ct value along with the positive report could potentially be used to guide patient care management, infection control, and occupational health decisions.