Diagnostic and prognostic significance of pericardial fluid biomarkers and a novel tumor-inflammation index in patients undergoing pericardiocentesis

Background Determining the underlying etiology of pericardial effusion remains a significant clinical challenge despite advances in cytological and microbiological diagnostic techniques. Biomarkers obtained directly from pericardial fluid may provide additional diagnostic and prognostic information, particularly in differentiating malignant from infectious causes (1,2). This study aimed to evaluate the diagnostic performance of established inflammatory and tumor-related biomarkers and to investigate the clinical utility of a novel composite index derived from these parameters. Methods In this retrospective single-center cohort study, 75 consecutive patients who underwent pericardiocentesis were analyzed. Pericardial fluid levels of interleukin-6 (IL-6), procalcitonin, adenosine deaminase (ADA), carcinoembryonic antigen (CEA), lactate dehydrogenase, and total protein were measured. A novel Pericardial Fluid Tumor–Inflammation Index (PFTI) was calculated as the ratio of CEA to ADA. Patients were categorized into malignant, bacterial infectious, tuberculous, and benign/idiopathic etiological groups. Group comparisons, receiver operating characteristic (ROC) curve analyses, and multivariable logistic regression were performed. Associations with 6-month mortality were also evaluated. Results Biomarker concentrations differed significantly across etiological groups (p < 0.001 for all comparisons). CEA levels and PFTI were markedly elevated in malignant effusions, whereas ADA was highest in tuberculous pericarditis and procalcitonin predominated in bacterial infection, consistent with prior biomarker-based differentiation studies (2–4). For the identification of malignancy, PFTI demonstrated the best diagnostic performance with an area under the curve (AUC) of 0.89 , 88% sensitivity, and 84% specificity at an optimal cut-off value of 0.75. CEA also showed excellent discrimination (AUC 0.88), in agreement with earlier reports demonstrating significantly higher CEA levels in malignant pericardial effusion and useful adjunctive diagnostic value alongside cytology (3,5). In multivariable logistic regression analysis, both PFTI and CEA remained independent predictors of malignant pericardial effusion (p < 0.001 for each). During follow-up, higher IL-6 and PFTI values were significantly associated with increased 6-month mortality, suggesting additional prognostic relevance beyond etiological differentiation and aligning with established risk-stratification concepts in pericardial disease (1). Conclusion The novel Pericardial Fluid Tumor–Inflammation Index (CEA/ADA) demonstrated excellent accuracy for identifying malignant pericardial effusion and was independently associated with short-term mortality. Incorporation of this simple and inexpensive index into routine pericardial fluid analysis may improve early etiological differentiation and clinical risk stratification.ROC-CURVE