Sensitivity of nasal and oropharyngeal swabs in diagnosing COVID-19 in hospitalised patients

Abstract

Background: To evaluate the sensitivity of nasal and oropharyngeal swabs in diagnosing COVID-19 in hospitalised patients and comparing patient factors and admission investigations to the swab result. Methods: Multicentre retrospective cohort study of all COVID-19 swab positive patients who were in-patients on 9th April 2020. Electronic case notes were analyzed for baseline characteristics including; age, gender, co-morbidities, admission blood tests and swab results. The results of each consecutive swab for COVID-19 was analysed for each patient. The number of swabs required to achieve a positive test was used to assess the sensitivity of the test. Results: Of the 173 patients identified, 108 (62.4%) were males, mean age was 68.4 ± 14.7 years. Commonest co-morbidity was hypertension (50.9%). 152 (87.9%) patients had their first swab positive. Age over 71 years was positively associated (53.3% vs. 23.8%, p = 0.018) and age-adjusted Charlson Comorbidity Index ≤ 2 was negatively associated (25.0% vs. 52.4%, p = 0.009) with the first swab being positive. Admission blood tests and chest X-ray findings did not influence the swab results. Conclusion: The sensitivity of swab for symptomatic and hospitalised patients was higher than previously thought and admission investigations do not predict the result of swab in COVID-19 positive patients.

Rights

© 2020 Khan KS, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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DOI

https://doi.org/10.36959/856/509

Repository URI

https://eprints.gla.ac.uk/303985/