Role of tumor necrosis factor-alpha in the differential diagnosis of parapneumonic effusion.

Objective: This study was undertaken to investigate the role of tumor necrosis factor-a (TNF-a) in discriminating between uncomplicated parapneumonic effusion (UCPPE) and complicated parapneumonic effusion (CPPE).

Method: Using a commercially available high sensitivity enzyme-linked immunosorbent assay (ELISA) kit, concentrations of TNF were measured in the serum (TNFs) and pleural fluid (TNFpf) of 21 patients with parapneumonic effusion (PPE), 13 patients with UCPPE, and 8 patients with nonempyemic CPPE.

Results: No significant difference in values of TNF concentration was found between the group with UCPPE and that with CPPE (P > 0.05). Concentration levels of TNFpf were significantly higher in the group with CPPE than in that with UCPPE (P = 0.0008). Levels of TNF in pleural fluid were significantly higher than in serum in both groups (P < 0.001). The ratio of TNF in pleural fluid to that in serum (TNFr) was significantly higher in the CPPE group than in the UCPPE group (P = 0.0002). At an optimal cutoff point of 10.7 pg/mL for TNFpf, the sensitivity was 87.5%, specificity was 92.3%, positive predictive value was 87.5%, negative predictive value was 93.3%, and total accuracy was 90.5% (P < 0.001). At an optimal cutoff point of 3.0 for TNFr, all values were 100% (P < 0.00001).

Conclusions: The results of this study indicate that TNFpf, and particularly TNFr, may be helpful in discriminating between UCPPE and CPPE. However, further studies are needed in a larger population to confirm these findings.