Lab Med Online.  2023 Oct;13(4):364-369. 10.47429/lmo.2023.13.4.364.

Correlation between Clinical Severity and Cycle Threshold Values of Real-time RT-PCR at the Time of Admission in COVID-19 Patients

• Yoo EH
• Lee AJ
• Kim SG
• Jeon CH

• KMID: 2552764
• DOI: http://doi.org/10.47429/lmo.2023.13.4.364

Abstract

Background
The viral load of the patient can be deduced from the cycle threshold (Ct) value. In this study, the correlation between the initial Ct value of the SARS-CoV-2 real-time reverse transcription polymerase chain reaction (RT-PCR) and the clinical features in hospitalized patients in Daegu, South Korea, was explored.
Methods
We investigated the clinical and RT-PCR data of 750 patients with COVID-19 (Coronavirus disease-19) at admission in eight hospitals in Daegu, Korea, and assessed the correlation between the Ct values and COVID-19 severity.
Results
The Ct values for the four genes showed a statistically significant difference (P < 0.001) within the same specimen type. Among the 716 patients classified based on clinical severity, the Ct value was a significant predictor of disease severity at the time of admission. The Ct values of the E, RdRP , and N genes showed significant differences among the eight severity groups (P < 0.001). Compared to patients in the non-severe group (categories 1 to 4), those in the severe group (categories 5 to 8) exhibited a relatively lower distribution of Ct values for the E (P < 0.001), RdRP (P =0.029), ORF1a (P =0.009), and N genes (P =0.003).
Conclusions
The Ct value, which reflects the amount of virus, can serve as a supportive parameter for predicting the severity of COVID-19 in patients at the time of admission.

Keyword

COVID-19; SARS-CoV-2; RT-PCR; Cycle threshold; Severity

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