Low Cycle Threshold of Coronavirus PCR Test Can Mean More Likelihood of Death

A team of researchers from the Montefiore Medical Center, Albert Einstein College of Medicine, asserted that the PCR cycle threshold (Ct) of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is believed to be an estimated measure of initial viral count. The study findings were published in the medRxiv, a preprint journal of health sciences.

The relationship of initial Ct at hospitalization and patient mortality has not been thoroughly investigated. Study implicates that the SARS-CoV-2 Ct value at the time of hospital admission is found to be an independent forecaster of in-patient mortality.

Source: British Society for Immunology

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has profoundly affected the entire world and these effects are expected to remain for years to come.  Approximately, to date, it has affected over 30 million of global population. Scientists, researchers, and clinicians, all are striving hard to identify the better diagnosis intervention with better predicting outcome and treatment modalities.

The polymerase chain reaction (rT-PCR) technology, is the standard test used worldwide for Covid-19 diagnosis. It works by giving “cycle threshold” (Ct), a number of PCR cycles required to cross the assigned threshold, which designates the patient positive for the infection. As per the study authors, the Ct value is inverse of the viral count, meaning if the threshold is large then the viral count will be low, and vise versa.

Source: British Society for Immunology

In this retrospective study of SARS-CoV-2 positive subjects, between March and August, up to 1044 hospitalized patients who have had SARS-CoV-2 were included and their Ct data within 48 hours of admission was evaluated. The data of up to 774 patients who had complete survival data were discharged and 270 died in the hospital were included in the analysis. Electronic medical records were used to retrieve the laboratory, demographic, and clinical data.

Source: medRxiv.

“A total of 1,044 patients met study inclusion criteria, of these 774 (74.1%) survived to discharge and 270 (25.9%) expired. In our cohort, 55.6% (580) patients were males and 44.4% (464) females with a mean age of 65.2 years (SD 15.37) and a mean BMI of 29.6 (SD 7.4). A history of hypertension (HTN) and Diabetes (DM) was present in 64.1% (629) and 40.8% (400), respectively. The majority of patients had group O blood-type, 46.5% (410), followed by group A blood-type, 31.6% (278),” says study.

The results reveal that the mean Ct value at the time of hospital admission was higher for survivors i-e 28.6, relative to the non-survivors i-e. 24.8. Patients who have had lower Ct value threshold and had higher in-patient mortality had higher incidence ratio of pre-existing health conditions and were aged.

In this study, scientists evaluated the Ct value and used it for predicting the deaths and compared it between different age and gender. They found that Ct value is significantly different between those individuals who survived and those who could not survive.  Yet, it still needs further elucidation to infer the better and proper application of Ct value in clinical settings.

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