COMPARING THE EFFECTIVENESS OF ADA/SERUM CRP RATIO, LYMPHOCYTES/NEUTROPHIL RATIO AND ADA IN DIFFERENTIATING TUBERCULOUS PLEURAL EFFUSION FROM EXUDATIVE EFFUSIONS

Abstract

Background: Tuberculous pleural effusion (TPE) is a frequent cause of exudative pleural effusion in regions with a high tuberculosis burden. Although pleural fluid adenosine deaminase (ADA) remains a key diagnostic tool, its specificity is compromised by elevated levels in other infectious and malignant diseases. Additional parameters, such as the lymphocyte-to-neutrophil (L/N) ratio and the ADA-to-serum C-reactive protein (CRP) ratio, have shown potential in improving diagnostic precision.

Materials and methods:A prospective study was carried out in the Department of TB and Respiratory Medicine at Saveetha Medical College and Hospital. Sixty patients above 15 years of age with exudative pleural effusion, confirmed using Light’s criteria, were enrolled. Patients with transudative effusions, HIV, malignancy, or age below 15 years were excluded. Clinical assessment, imaging, and laboratory investigations including pleural ADA, L/N ratio, and ADA/CRP ratio were performed. Statistical analysis was conducted using SPSS version 26.

Results:Among the participants, 57% were diagnosed with TPE and 43% with non-TB effusions. ADA levels above 40 U/L yielded a sensitivity of 89.35% and specificity of 68.9%. The L/N ratio (>0.75) demonstrated superior performance, with 98.44% sensitivity and 82.70% specificity. The ADA/CRP ratio (>1.25) proved useful in cases with borderline ADA levels. When all three parameters were used together, the diagnostic accuracy reached 100% sensitivity and 85.47% specificity, with a positive predictive value of 89.17% and a negative predictive value of 95.67%.

Conclusion:Integrating pleural ADA, L/N ratio, and ADA/CRP ratio offers markedly higher diagnostic accuracy for TPE compared with ADA alone. This combined biomarker strategy may reduce the need for invasive procedures and allow for faster initiation of treatment in high TB-prevalence settings.