Proposal of COVID-19 Clinical Risk Score for the management of suspected COVID-19 cases: a case control study

Background: No clinical scoring system has yet been established to estimate the likelihood of COVID-19 and to determine the suitability of diagnostic testing in suspected COVID-19 patients. Methods: This was a single-center, retrospective, observational study of patients with suspected COVID-19 and confirmed COVID-19. Patient background, clinical course, laboratory and CT findings, and the presence of alternative diagnoses were evaluated. Clinical risk scores were developed based on clinical differences between patients with and those without COVID-19. Results: Among 110 patients suspected of COVID-19, 60.9% underwent PCR testing based on the judgment of physicians. Two patients were found to have COVID-19. The clinical characteristics of 108 non-COVID-19 patients were compared with those of 23 confirmed COVID-19 patients. Patients with COVID-19 were more likely to have a history of high-risk exposures and abnormal sense of taste and smell. Significantly higher rates of subnormal white blood cell count, lower eosinophil count, and lower procalcitonin level were observed in the COVID-19 group than in the non-COVID-19 group. When blood tests, CT findings, and the presence of alternative diagnoses were scored on an 11-point scale, i.e., “COVID-19 Clinical Risk Score”, the COVID-19 group scored significantly higher than the non-COVID-19 group, with more than four points in the COVID-19 group. All non-COVID cases that did not undergo PCR had a score of 4 or less. Conclusions: The COVID-19 Clinical Risk Score enables risk classification of patients suspected of having COVID-19 and can help in decision-making in clinical practice, including appropriateness of diagnostic testing.