Maya Makov-Assif1, Sydney Krispin1, Yatir Ben-Shlomo1, Tal Holander1, Noa Dagan1,2, Ran Balicer1,3, Noam Barda1,2. 1. Innovation Division, Clalit Research Institute, Clalit Health Services, Tel Aviv, Israel. 2. Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA. 3. Faculty of Health Sciences, School of Public Health, Ben Gurion University of the Negev, Sheva, Be'er, Israel.
Abstract
BACKGROUND: COVID-19 continues to spread throughout the world. Real-time reverse transcriptase polymerase chain reaction (RT-PCR) is used to diagnose COVID-19, with its cycle threshold (Ct) value inversely related to the viral load. The association between Ct values and COVID-19 related outcomes has been studied in the hospital setting but less so in the community. We aimed to estimate the association between Ct values and the severity of community-diagnosed COVID-19 to provide evidence on the utility of Ct testing in this setting. METHODS: This was a retrospective cohort study based on data from Israel's largest health organization. The study population included 34,658 individuals who tested positive for COVID-19 by RT-PCR and had available Ct values between June 1st and December 21st, 2020. Outcomes included COVID-19 related symptoms, hospitalization, severe disease, and death. Ct values were modelled both as discrete and continuous exposures. RESULTS: After adjusting for known risk factors for severe COVID-19, low Ct values were associated with symptomatic disease (odds ratio [OR]: 1.51; 95% confidence interval [CI]:1.21-1.84), hospitalization (OR: 1.27; 95%CI: 1.12-1.49), severe disease (OR: 1.80; 95%CI: 1.43-2.27), and death (OR: 1.64; 95%CI: 1.06-2.59). By modelling the exposure as continuous, we noticed a dose-response relationship, with the risk gradually rising with lower Ct values. CONCLUSIONS: This study found a significant association between low Ct values and severe COVID-19 related outcomes, with a dose-response relationship. This suggests that Ct values could be helpful in identifying high-risk patients diagnosed in the community.
BACKGROUND: COVID-19 continues to spread throughout the world. Real-time reverse transcriptase polymerase chain reaction (RT-PCR) is used to diagnose COVID-19, with its cycle threshold (Ct) value inversely related to the viral load. The association between Ct values and COVID-19 related outcomes has been studied in the hospital setting but less so in the community. We aimed to estimate the association between Ct values and the severity of community-diagnosed COVID-19 to provide evidence on the utility of Ct testing in this setting. METHODS: This was a retrospective cohort study based on data from Israel's largest health organization. The study population included 34,658 individuals who tested positive for COVID-19 by RT-PCR and had available Ct values between June 1st and December 21st, 2020. Outcomes included COVID-19 related symptoms, hospitalization, severe disease, and death. Ct values were modelled both as discrete and continuous exposures. RESULTS: After adjusting for known risk factors for severe COVID-19, low Ct values were associated with symptomatic disease (odds ratio [OR]: 1.51; 95% confidence interval [CI]:1.21-1.84), hospitalization (OR: 1.27; 95%CI: 1.12-1.49), severe disease (OR: 1.80; 95%CI: 1.43-2.27), and death (OR: 1.64; 95%CI: 1.06-2.59). By modelling the exposure as continuous, we noticed a dose-response relationship, with the risk gradually rising with lower Ct values. CONCLUSIONS: This study found a significant association between low Ct values and severe COVID-19 related outcomes, with a dose-response relationship. This suggests that Ct values could be helpful in identifying high-risk patients diagnosed in the community.
Entities:
Keywords:
COVID-19; RT-PCR; community; cycle threshold; severe COVID-19
Authors: Ali S Al-Shareef; Bader Shirah; Mohammed Dabroom; Mohammed M Ahmed; Khalid A Aljohani; Mona A Al Dabbagh; Majid Ramadan; Fahad Hakami Journal: Cureus Date: 2022-07-06