Elsevier

Journal of Infection

Volume 82, Issue 6, June 2021, Pages 260-268
Journal of Infection

Sensitivity of SARS-CoV-2 RNA polymerase chain reaction using a clinical and radiological reference standard

https://doi.org/10.1016/j.jinf.2021.04.012Get rights and content

Highlights

  • Compared to a clinical and radiological standard, SARS-CoV-2 PCR sensitivity was 68%.

  • Sensitivity declined after one week from patient-reported symptom onset.

  • Test sensitivity was lower among current smokers compared to never/former smokers.

  • Lower test sensitivity among smokers may explain lower observed disease incidence.

Abstract

Objectives

Diagnostic tests for SARS-CoV-2 are important for epidemiology, clinical management, and infection control. Limitations of oro-nasopharyngeal real-time PCR sensitivity have been described based on comparisons of single tests with repeated sampling. We assessed SARS-CoV-2 PCR clinical sensitivity using a clinical and radiological reference standard.

Methods

Between March-May 2020, 2060 patients underwent thoracic imaging and SARS-CoV-2 PCR testing. Imaging was independently double- or triple-reported (if discordance) by blinded radiologists according to radiological criteria for COVID-19. We excluded asymptomatic patients and those with alternative diagnoses that could explain imaging findings. Associations with PCR-positivity were assessed with binomial logistic regression.

Results

901 patients had possible/probable imaging features and clinical symptoms of COVID-19 and 429 patients met the clinical and radiological reference case definition. SARS-CoV-2 PCR sensitivity was 68% (95% confidence interval 64–73), was highest 7-8 days after symptom onset (78% (68–88)) and was lower among current smokers (adjusted odds ratio 0.23 (0.12–0.42) p < 0.001).

Conclusions

In patients with clinical and imaging features of COVID-19, PCR test sensitivity was 68%, and was lower among smokers; a finding that could explain observations of lower disease incidence and that warrants further validation. PCR tests should be interpreted considering imaging, symptom duration and smoking status.

Keywords

SARS-CoV-2
COVID-19
Real-time polymerase chain reaction
Radiology
Diagnostic X-Ray
Diagnostic testing
Sensitivity and specificity

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