Comparison of clinical characteristics and outcome in RT-PCR positive and false-negative RT-PCR for COVID-19: A Retrospective analysis

Abstract

Cases with SARS-CoV-2 RT-PCR negative pneumonia are an understudied group with uncertainty remaining regarding their treatment approach. We aimed to compare the clinical and radiological characteristics of RT-PCR positive and clinically diagnosed RT-PCR negative COVID-19. This was a single-centre retrospective study conducted at a tertiary care hospital in Western India. All patients (age ≥18 years) with suspicion of COVID-19 with SARI (severe acute respiratory infections) who were subjected to RT-PCR testing (nasal/ oropharyngeal swab) were included. Based on RT-PCR results, patients were categorized and compared for demographic, clinical, and biochemical characteristics and outcomes. Out of 500 patients, 339 (67.8%) found RT-PCR positive. Except for the radiological findings, both groups differ in clinical presentation, disease severity (inflammatory markers), and outcome. RT-PCR-positive patients had raised ferritin, NLR SUMMARY (Neutrophil-Lymphocyte ratio), LDH, and high mortality compared to the swab-negative group. In-hospital mortality was also significantly high in RT-PCR positive group (HR=1.9, 95% CI=1.4-2.5, p=0.001). On multivariate analysis, NLR, ferritin, and d-dimer were the independent predictors of mortality in RT-PCR-positive (p=0.038, 0.054, and 0.023). At the same time, raised TLC (total leukocyte count) and procalcitonin were the risk factors for poor outcomes in RT-PCR-negative patients (p=0.041 and 0.038). We found significantly raised ferritin, NLR, and LDH levels and increased mortality in RT-PCR positive patients compared to RT-PCR negative. Incorporating clinical features, radiological, and biochemical parameters could be prudent while managing the RT-PCR-negative patients.