Abstract
IntroductionSpecific patterns of blood test results are associated with COVID-19 infection. The aim of this study was to identify which blood tests could be used to assist in diagnosing COVID-19.MethodA retrospective review was performed on consecutive patients referred to hospital with a clinical suspicion of COVID-19 over a period of four weeks. The patient’s clinical presentation and severe acute respiratory syndrome coronavirus 2 reverse-transcription polymerase chain reaction (SARS-CoV-2 RT-PCR) were recorded. The patients were divided by diagnosis into COVID (COVID-19 infection) or CONTROL (an alternate diagnosis). A retrospective review of consecutive patients over a further two-week period was used for the purposes of validation.ResultsOverall, 399 patients (53% COVID, 47% CONTROL) were analysed. White cell count, neutrophils and lymphocytes were significantly lower, while lactate dehydrogenase and ferritin were significantly higher, in the COVID group in comparison to CONTROL. Combining the white cell count, lymphocytes and ferritin results into a COVID Combined Blood Test (CCBT) had an area under the curve of 0.79. Using a threshold CCBT of –0.8 resulted in a sensitivity of 0.85 and a specificity of 0.63. Analysing this against a further retrospective review of 181 suspected COVID-19 patients, using the same CCBT threshold, resulted in a sensitivity of 0.73 and a specificity of 0.75. The sensitivity was comparable to the SARS-CoV-2 RT PCR.DiscussionMathematically combining the blood tests has the potential to assist clinical acumen allowing for rapid streaming and more accurate patient flow pending definitive diagnosis. This may be of particular use in low-resource settings.
Highlights
Specific patterns of blood test results are associated with COVID-19 infection
We aimed to (1) identify how blood tests differ between patients who are diagnosed with COVID19, and those who are not, in patients referred for possible COVID-19 and (2) attempt to mathematically combine blood test results together to assess if this could be used to support a diagnosis of COVID-19
A clinical diagnosis of COVID-19 was made in 213 patients (53%) (COVID group) following consideration of symptoms, radiology, blood tests and a SARS-CoV-2 reverse-transcription polymerase chain reaction (RT-PCR) with 186 (47%) diagnosed with not having COVID-19 based on the same considerations (CONTROL group)
Summary
Specific patterns of blood test results are associated with COVID-19 infection. The aim of this study was to identify which blood tests could be used to assist in diagnosing COVID-19. While a positive test for SARS-CoV-2 generally confirms the diagnosis of COVID-19, false-negative tests, It has been established that COVID-19 infection is associated with patterns of blood test results among hospitalized patients. These include a raised lactate dehydrogenase (LDH), inflammatory markers (e.g. ferritin [FER], C-reactive protein [CRP], aminotransferases and d-dimers5,6) and lymphopenia. These blood tests, at particular levels, have been associated with a worse prognosis in COVID-19 patients[7,8,9] and have been shown to differentiate between those who are SARS-CoV-2 RT-PCR negative and positive.[10] this does not account for the proportion of patients who are SARS-CoV-2neg but are considered to have COVID-19 clinically. We aimed to (1) identify how blood tests differ between patients who are diagnosed with COVID19, and those who are not, in patients referred for possible COVID-19 and (2) attempt to mathematically combine blood test results together to assess if this could be used to support a diagnosis of COVID-19
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