Clinical characteristics and predictors of pneumonia in patients presenting fever or respiratory symptoms with normal or low leukocyte counts: a retrospective study

Abstract

Background Many patients went to the hospital presenting with acute fever, or respiratory symptoms, most of whom have a normal or low leukocyte counts. The aim of this study was to investigate the clinical characteristics and predictors of pneumonia in those patients. Methods In this retrospective study, adult patients (≥ 18 years old) presenting with acute fever or respiratory symptoms with normal or low leukocyte counts (≤ 9.5 × 109/L) in Peking Union Medical College Hospital between 26 January 2020 and 10 March 2020 were included. Patients were categorized into groups with pneumonia or upper respiratory tract infection (URTI) according to chest CT scans. Logistic regression was used to explore predictors of pneumonia. Results A total of 195 patients were included, 63 of whom were diagnosed with pneumonia. The median maximum body temperature was 38.5 °C (38.0-38.8 °C) in patients with pneumonia and 37.5 °C (37.4–37.8 °C) in the other group. There was a significant difference in high-sensitivity C-reactive protein (hsCRP) levels between the two groups (0.21 (0-3.74) versus 33.4 (15.5–75.5) mg/L, p < 0.001). Multivariable regression showed that the predictive values of pneumonia were older age (OR 1.06, 95% CI 1.02–1.10, p = 0.004), cough (OR 0.18, 95%CI 0.06–0.56; p = 0.003), higher temperature (OR 3.36, 95%CI 1.16–9.71; p = 0.025) and higher hsCRP level (OR 1.05, 95%CI 1.02–1.09; p = 0.003). The optimal cutoff values based on the ROC curve analysis were a temperature of 37.8 °C and a hsCRP level of 1.64 mg/L. Conclusions Patients with older age, cough, higher temperature and higher hsCRP level were more inclined to have pneumonia. Temperatures higher than 37.8 °C were a potential predictor of pneumonia in patients with normal or low leukocyte counts in the early stage. However, a hsCRP level less than 1.64 mg/L could rule out most cases of pneumonia.