Cycle threshold values are inversely associated with poorer outcomes in hospitalized patients with COVID-19: a prospective, observational cohort study conducted at a UK tertiary hospital

Jenny Wright,Felix Achana,Lavanya Diwakar,Malcolm G Semple,Will D Carroll,Kenneth Baillie,Christopher Thompson,Alice Alcock,Timothy S Kemp

doi:10.1016/j.ijid.2021.08.022

Abstract

This single-centre observational study demonstrated that lower cycle threshold (Ct) values (indicating higher viral loads) on admission to hospital were associated with poorer outcomes in unvaccinated, hospitalized patients with coronavirus disease 2019 (COVID-19). Demographic and outcome data were collected prospectively for all adult patients who tested positive for severe acute respiratory syndrome coronavirus-2 on admission to the University Hospitals North Midlands NHS Trust between 1 February and 1 July 2020. Nasopharyngeal swab samples were obtained, and a valid Ct value was determined for all patients using the Viasure reverse transcription polymerase chain reaction assay, validated by Public Health England, on admission to hospital. Multi-variable logistic regression results based on data from 618 individuals demonstrateda significant inverse relationship between the odds of death and Ct values (adjusted odds ratio 0.95, 95% confidence interval 0.92-0.98, P=0.001).The association remained highly significant after adjusting for known clinical risk factors for COVID-19.

Highlights

Clinicians need to identify patients with coronavirus disease 2019 (COVID-19) with a higher risk of poor outcome and mortality at an early stage of hospital admission
803 SARS-CoV-2-positive adults (>18 years of age) with a valid cycle threshold (Ct) value determined on admission to hospital were eligible for inclusion in this study, and were followed-up for a period of up to 28 days (Figure 1)
Thirty-five percent of participants had a history of cardiovascular disease, 18% had chronic pulmonary disease, 19% had chronic kidney disease, 14% were asthmatic, 13% had either complicated or uncomplicated diabetes, and 7% were obese

Summary

Introduction

Clinicians need to identify patients with coronavirus disease 2019 (COVID-19) with a higher risk of poor outcome and mortality at an early stage of hospital admission. This prospective, observational cohort study was conducted at a UK tertiary care hospital to determine the relationship between the likelihood of death and cycle threshold (Ct) values in an unvaccinated UK population with COVID-19 on admission to hospital. Statistical adjustment was made for other known risk factors associated with poor outcome. Ct values are semi-quantitative values which are inversely proportional to the viral load in a reverse transcription polymerase chain reaction (PCR) test for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)

Methods

Results

Conclusion