Efficiency of Lymphocyte-to-Monocyte Ratio in Differential Diagnosis of Parapneumonic Effusion and Thoracic Empyema

Abstract

Background: Parapneumonic effusion (PPE) and thoracic empyema (TE) necessitate prompt differential diagnosis regarding their unequal rates of mortality and disparate methods of treatment. Patients and Methods: A total of 80 patients with equally divided between the PPE and TE groups were evaluated in terms of age, gender, side of the affected hemithorax, and peripheral blood counts including white blood cell (WBC) count, C-reactive protein (CRP), lymphocyte, monocyte, and lymphocyte-to-monocyte ratio (LMR). Results: The difference between the two groups in terms of age, gender, side of the disease, and monocyte count was not statistically significant (p > 0.05) whereas WBC count, lymphocyte, and LMR was significantly higher in the TE group (p < 0.05). Lymphocyte-to-monocyte ratio over 2.45 was a differential diagnostic test of PPE and TE at 85% sensitivity and 87.5% specificity. Conclusions: Lymphocyte-to-monocyte ratio is an effective indicator to finalize the differential diagnosis of PPE and TE when combined with high levels of serum WBC, CRP, and lymphocytes in addition to clinical and radiologic findings.