Differentiating Between 2019 Novel Coronavirus Pneumonia and Influenza Using a Nonspecific Laboratory Marker–Based Dynamic Nomogram

Background There is currently a lack of nonspecific laboratory indicators as a quantitative standard to distinguish between the 2019 coronavirus disease (COVID-19) and an influenza A or B virus infection. Thus, the aim of this study was to establish a nomogram to detect COVID-19. Methods A nomogram was established using data collected from 457 patients (181 with COVID-19 and 276 with influenza A or B infection) in China. The nomogram used age, lymphocyte percentage, and monocyte count to differentiate COVID-19 from influenza. Results Our nomogram predicted probabilities of COVID-19 with an area under the receiver operating characteristic curve of 0.913 (95% confidence interval [CI], 0.883–0.937), greater than that of the lymphocyte:monocyte ratio (0.849; 95% CI, 0.812–0.880; P = .0007), lymphocyte percentage (0.808; 95% CI, 0.768–0.843; P < .0001), monocyte count (0.780; 95% CI, 0.739–0.817; P < .0001), or age (0.656; 95% CI, 0.610–0.699; P < .0001). The predicted probability conformed to the real observation outcomes of COVID-19, according to the calibration curves. Conclusions We found that age, lymphocyte percentage, and monocyte count are risk factors for the early-stage prediction of patients infected with the 2019 novel coronavirus. As such, our research provides a useful test for doctors to differentiate COVID-19 from influenza.