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. 2004 Nov 23;171(11):1349-52.
doi: 10.1503/cmaj.1040398.

Initial viral load and the outcomes of SARS

Chung-Ming Chu  1 , Leo L M Poon, Vincent C C Cheng, Kin-Sang Chan, Ivan F N Hung, Maureen M L Wong, Kwok-Hung Chan, Wah-Shing Leung, Bone S F Tang, Veronica L Chan, Woon-Leung Ng, Tiong-Chee Sim, Ping-Wing Ng, Kin-Ip Law, Doris M W Tse, Joseph S M Peiris, Kwok-Yung Yuen
Affiliations

Initial viral load and the outcomes of SARS

Chung-Ming Chu et al. CMAJ. .

Abstract

Background: Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus. It may progress to respiratory failure, and a significant proportion of patients die. Preliminary data suggest that a high viral load of the SARS coronavirus is associated with adverse outcomes in the intensive care unit, but the relation of viral load to survival is unclear.

Methods: We prospectively studied an inception cohort of 133 patients with virologically confirmed SARS who were admitted to 2 general acute care hospitals in Hong Kong from Mar. 24 to May 4, 2003. The patients were followed until death or for a minimum of 90 days. We used Cox proportional hazard modelling to analyze potential predictors of survival recorded at the time of presentation, including viral load from nasopharyngeal specimens (measured by quantitative reverse transcriptase polymerase chain reaction [PCR] of the SARS-associated coronavirus).

Results: Thirty-two patients (24.1%) met the criteria for acute respiratory distress syndrome, and 24 patients (18.0%) died. The following baseline factors were independently associated with worse survival: older age (61-80 years) (adjusted hazard ratio [HR] 5.24, 95% confidence interval [CI] 2.03-13.53), presence of an active comorbid condition (adjusted HR 3.36, 95% CI 1.44-7.82) and higher initial viral load of SARS coronavirus, according to quantitative PCR of nasopharyngeal specimens (adjusted HR 1.21 per log10 increase in number of RNA copies per millilitre, 95% CI 1.06-1.39).

Interpretation: We found preliminary evidence that higher initial viral load is independently associated with worse prognosis in SARS. Mortality data for patients with SARS should be interpreted in light of age, comorbidity and viral load. These considerations will be important in future studies of SARS.

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Figures

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Fig 1: Kaplan–Meier survival curves according to level of SARS coronavirus (on the basis of number of RNA copies per millilitre), as determined by quantitative reverse transcriptase polymerase chain reaction of initial nasopharyngeal specimens.
See this image and copyright information in PMC

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