Comparison between Suspected and Confirmed COVID-19 Respiratory Patients: What Is beyond the PCR Test

Abstract

COVID-19 modified the healthcare system. Nasal-pharyngeal swab (NPS), with real-time reverse transcriptase-polymerase (PCR), is the gold standard for the diagnosis; however, there are difficulties related to the procedure that may postpone it. The study aims to evaluate whether other elements than the PCR-NPS are reliable and confirm the diagnosis of COVID-19. This is a cross-sectional study on data from the Lung Unit of Pavia (confirmed) and at the Emergency Unit of Palermo (suspected). COVID-19 was confirmed by positive NPS, suspected tested negative. We compared clinical, laboratory and radiological variables and performed Logistic regression to estimate which variables increased the risk of COVID-19. The derived ROC-AUCcurve, assessed the accuracy of the model to distinguish between COVID-19 suspected and confirmed. We selected 50 confirmed and 103 suspected cases. High Reactive C-Protein (OR: 1.02; CI95%: 0.11-1.02), suggestive CT-images (OR: 11.43; CI95%: 3.01-43.3), dyspnea (OR: 10.48; CI95%: 2.08-52.7) and respiratory failure (OR: 5.84; CI95%: 1.73-19.75) increased the risk of COVID-19, whereas pleural effusion decreased the risk (OR: 0.15; CI95%: 0.04-0.63). ROC confirmed the discriminative role of these variables between suspected and confirmed COVID-19 (AUC 0.91). Clinical, laboratory and imaging features predict the diagnosis of COVID-19, independently from the NPS result.

Keywords: COVID-19; COVID-19 diagnosis; PCR test.

Figure 1

ROC-AUC report the high accuracy of the model in distinguishing the diagnosis of COVID-19 between the two groups.