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Association of cycle threshold values of CBNAAT with severity and outcome in COVID-19
Kranti Garg1, Karan Sharma2, Aditi Gupta3
1Department of Pulmonary Medicine, Government Medical College, Patiala. drkrantigarg@yahoo.com.
Insights
Cycle threshold (Ct) values, indicating viral load, can predict COVID-19 severity and outcomes. Lower Ct values (higher viral load) correlate with increased severity and mortality in coronavirus disease 2019 patients.
Area of Science:
- Virology
- Infectious Diseases
- Public Health
Background:
- Cycle threshold (Ct) values in viral load testing for COVID-19 may predict disease severity and patient outcomes.
- Existing literature on this relationship is variable, necessitating further investigation.
Purpose of the Study:
- To explore the association between viral load (Ct values) and COVID-19 severity and outcomes.
- To investigate the influence of socio-demographic and clinical factors on COVID-19 severity and outcomes.
Main Methods:
- Retrospective analysis of 731 COVID-19 patients' records.
- Utilized cartridge-based nucleic acid amplification testing (CBNAAT) for SARS-CoV-2 detection.
- Analyzed Ct values of N2 and E genes in relation to disease severity and mortality.
Main Results:
- Higher viral load (lower Ct values) of N2 and E genes correlated significantly with increased COVID-19 severity and mortality.
- Elderly patients, rural background, symptom duration >7 days, and comorbidities were associated with worse outcomes.
- Ct values >32 for N2 gene indicated significantly lower severity and mortality risk.
Conclusions:
- Ct values of N2 and E genes serve as reliable surrogate markers for predicting COVID-19 severity and disease outcomes.
- Understanding these markers can aid in patient risk stratification and management.
Abstract:
Determination of viral load through cycle threshold (Ct) values may act as a predictor of severity and outcomes in patients with corona virus disease 2019 (COVID-19). However, variable literature is available regarding this relationship. Our study attempted to explore this association and the effect of various socio-demographic and clinical parameters on severity and outcome of COVID-19. Retrospective analysis of records of 731 patients whose nasopharyngeal/oropharyngeal swabs were subjected to cartridge based nucleic acid amplification (CBNAAT) on Cepheid Xpert Xpress SARS-CoV-2 was done. Ct values of N2 and E genes were studied in relation to severity and outcome of COVID-19. The viral load as determined by Ct values was classified as high (<25), medium (25.1-32) and low (>32). Association of socio-demographic and clinical parameters with respect to severity and outcome was also studied. Severity and mortality were significantly more in elder individuals, those belonging to the rural background, those with symptoms >7 days in duration before presentation and those with increasing number of co-morbidities (severity: p<0.001; mortality: p<0.001, 0.005, 0.006 and <0.001, respectively). The Ct values of gene N2 and E inversely correlated with severity and mortality from the disease (N2 gene: p=0.001 for both severity and mortality, E gene: severity: p<0.001, mortality: p=0.016, respectively). The severity of the illness and chances of mortality were significantly lesser when the CT value of N2 gene was >32, in comparison when it was upto 25, and when between 25.1 and 32 (severity: p=0.032 and 0.003, respectively; mortality: p=0.018 and <0.001, respectively). Almost similar trends were seen with respect to E gene (severity: p<0.001 and 0.067, respectively; mortality p=0.175 and 0.005, respectively). Viral load as determined by Ct values of N2 and E genes can act as surrogate markers for prediction of severity and disease outcomes in COVID-19.
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