Association Between Reverse Transcription Polymerase Chain Reaction Cycle Thresholds and Outcomes of Individuals Hospitalized for Coronavirus Disease 2019

Background: Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can lead to a wide spectrum of clinical severity. The gold standard diagnosis of infection is reverse transcription polymerase chain reaction of nasopha-ryngeal swabs, which also provides a semiquantitative assessment of viral loads by measuring cycle threshold (CT) values. Objective: To assess whether CT values at admission can predict mortality and oxygen needs among individuals hospitalized for coronavirus disease 2019 (COVID-19). Methods: The retrospective study included adults hospitalized for COVID-19 between 1 August 2020 and 30 April 2021 at Barzilai University Medical Center. Patients were categorized according to initial CT values as high (≥ 25) or low (< 25) values. The primary outcome was the association between CT values during admission and overall mortality. Results: The study group included 636 patients, with a mean age of 67.2 years, 54.4% males. Overall mortality of patients with CT values < 25 was significantly higher (odds ratio for mortality 1.78 vs. patients with CT ≥ 25, P = 0.002). Significantly more patients in the low CT group required oxygen support than in the high CT group, 50% vs. 31.9% (P < 0.001). An inverse association between CT values and mortality rates remained significant in multivariate regression analysis, such that a 1-unit decrease in CT was associated with a 6% increased mortality. Conclusions: Lower CT values at admission were associated with increased mortality among patients hospitalized for COVID-19. CT values can be used to predict outcomes among such patients.