Open AccessSensitivity of RT-PCR testing of upper respiratory tract samples for SARS-CoV-2 in hospitalised patients: a retrospective cohort study
Author(s) -
Thomas C Williams,
Elizabeth Wastnedge,
Gina McAllister,
Ramya Bhatia,
Kate Cuschieri,
Kallirroi Kefala,
Fiona Hamilton,
Ingólfur Johannessen,
Ian F. Laurenson,
Jill Shepherd,
Alistair Stewart,
Donald Waters,
Helen Wise,
Kate Templeton
Publication year - 2022
Publication title -
wellcome open research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.298
H-Index - 21
ISSN - 2398-502X
DOI - 10.12688/wellcomeopenres.16342.2
Subject(s) - medicine , respiratory tract infections , ns3 , respiratory system , virology , gastroenterology , virus , hepatitis c virus
Background: This study aimed to determine the sensitivity and specificity of reverse transcription PCR (RT-PCR) testing of upper respiratory tract samples from hospitalised patients with coronavirus disease 2019 (COVID-19), compared to the gold standard of a clinical diagnosis. Methods: All RT-PCR testing for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in NHS Lothian, Scotland, United Kingdom between the 7 th of February and 19 th April 2020 (inclusive) was reviewed, and hospitalised patients were identified. All upper respiratory tract RT-PCR tests were analysed for each patient to determine the sequence of negative and positive results. For those who were tested twice or more but never received a positive result, case records were reviewed, and a clinical diagnosis of COVID-19 allocated based on clinical features, discharge diagnosis, and radiology and haematology results. For those who had a negative RT-PCR test but a clinical diagnosis of COVID-19, respiratory samples were retested using a multiplex respiratory panel, a second SARS-CoV-2 RT-PCR assay, and a human RNase P control. Results: Compared to the gold standard of a clinical diagnosis of COVID-19, the sensitivity of a single upper respiratory tract RT-PCR for COVID-19 was 82.2% (95% confidence interval 79.0-85.1%). The sensitivity of two upper respiratory tract RT-PCR tests increased sensitivity to 90.6% (CI 88.0-92.7%). A further 2.2% and 0.9% of patients who received a clinical diagnosis of COVID-19 were positive on a third and fourth test; this may be an underestimate of the value of further testing as the majority of patients 93.0% (2999/3226) only had one or two RT-PCR tests. Conclusions: The sensitivity of a single RT-PCR test of upper respiratory tract samples in hospitalised patients is 82.2%. Sensitivity increases to 90.6% when patients are tested twice. A proportion of cases with clinically defined COVID-19 never test positive on RT-PCR despite repeat testing.