False-negative real-time polymerase chain reaction tests in COVID-19 patients: an epidemiological analysis of 302 patients

OBJECTIVES: Patients who arrive at the emergency department (ED) with COVID-19, who test negative at the first real-time polymerase chain reaction (RT-PCR), represent a clinical challenge. This study aimed to evaluate if the clinical manifestation at presentation, the laboratory and imaging results, and the prognosis of COVID-19 differ in patients who tested negative at the first RT-PCR compared with those who tested positive and also to evaluate if comorbid conditions patient-related or the period of arrival are associated with negative testing. STUDY DESIGN: We retrospectively collected clinical data of patients who accessed the ED from March 1 to May 15, 2020. METHODS: We compared clinical variables, comorbid conditions, and clinical outcomes in the two groups by univariate analysis and logistic regression. RESULTS: Patients who tested negative at the first RT-PCR showed a higher prevalence of cardiopathy, immunosuppression, and diabetes, as well as a higher leukocyte and lower lymphocyte counts compared with patients who tested positive. A bilateral interstitial syndrome and a typical pattern at computed tomography scan were prevalent in the test-negative group. Test-negative patients were more likely to be admitted to the hospital but less likely to need admission in a high level of care ward. The false-negative rate increased from March to May. CONCLUSION: False-negative RT-PCR COVID-19 patients present a similar spectrum of symptoms compared with positive cohort, but more comorbidities. Imaging helps to identify them. True positives had a higher risk of serious complications.