Correlation of white blood cell count and severity of injury in abdominal trauma; a cross-sectional study

Few studies exist regarding the relationship between white blood cell (WBC) count and abdominal injury, and their findings are sometime contradictory. In addition, due to the different mechanisms proposed for the increase in WBC count following trauma, it is not yet known which type of these cells increase following trauma. Thus, the present study was designed aiming to evaluate the relationship between WBC count and injury severity in abdominal trauma. The present retrospective cross-sectional study was done on abdominal injury patients over 18 years old. Extracted data included demographic data (age, sex), injury severity score (ISS), and WBC count. Patients were divided into 2 groups based on ISS, namely mild injury (ISS <16) and severe injury (ISS ≥ 16). The correlation of WBC count with injury severity was evaluated based on linear regression and area under receiver operating characteristic (ROC) curve. 186 patients were included (mean age 37.8 ± 12.1 years old; 79.0% male). A significant direct correlation was found between ISS with total WBC (R2=0.46; β=0.26, 95% CI: 0.22-0.30; p < 0.0001) and neutrophil (R2=0.43; β=0.24, 95% CI: 0.20-0.28; p < 0.0001) counts in blood. Area under the ROC curve of WBC, neutrophil, lymphocyte, and other cells (monocytes, eosinophil, and basophils) counts were 0.84 (95% CI: 0.78-0.90), 0.81 (95% CI: 0.75-0.87), 0.63 (95% CI: 0.55-0.71), and 0.56 (95% CI: 0.47-0.64), respectively. Area under the ROC curve for WBC and neutrophil counts were significantly larger than that of lymphocyte and other cells in diagnosis of severe injuries (p < 0.0001). Findings of the present study showed that following abdominal trauma, WBC count increases in blood. The effect of trauma on increasing the cells is greater on neutrophils compared to other cells. However, moderate discriminatory power of WBC count in prediction of severe injuries limits its use for diagnosis of severe abdominal injuries.