Clinical and biochemical characteristics and outcomes of suspected COVID-19 hospitalized patients: RT-PCR swab positive and negative comparison

BACKGROUND: COVID-19 is diagnosed using RT-PCR assays of samples from nasal and oropharyngeal swabs. People with negative RT-PCR often presented with clinical manifestations of COVID-19. The data on such patients are lacking. The present study aims to characterize the patients who were suspected COVID-19 cases and tested negative in RT-PCR compared to patients who had been tested RT-PCR positive. METHODS: This is a retrospective, observational study of adult suspected and confirmed patients of COVID-19 admitted to King Saud University Medical City, Riyadh, Saudi Arabia, from 1st March 2020 until 30th November 2020. Laboratory confirmation is done through nasal/pharyngeal swab specimens, tested positive in RT-PCR assay. Patients with initial negative RT-PCR test results were assessed again within 48−72 h to avoid false-negative results. Patient data were extracted from the electronic medical files of each included patient using a predesigned case report form. RESULTS: The study included 488 (80.93%) patients with RT-PCR swab results positive, and 115 (19.07%) patients who were negative. Respiratory rate and diastolic blood pressure were higher among the swab-positive cases. More number of swab-negative patients had comorbidities such as coronary heart disease, chronic kidney disease, and carcinoma. Fever, cough, and shortness of breath were reported higher among the swab-positive cases. ALT and AST, and LDH levels were found higher among RT-PCR-positive patients. Serum creatinine, blood urea nitrogen and troponin were more elevated in RT-PCR-negative patients. Antibiotics, anticoagulants, and corticosteroids were used more by swab-positive patients. Significantly higher number of RT-PCR-positive patients required proning, high-flow nasal cannula, non-invasive mechanical ventilation, and invasive mechanical ventilation. Acute cardiac ischemia and death were found to be similar among the patients. However, deaths occurred significantly earlier among the swab-positive cases when compared to the swab-negative group. CONCLUSION: Distinctive symptoms and markers of COVID-19 are more frequent among patients who had RT-PCR-positive results.