Diagnostic and Prognostic Value of Plasma D-dimer Levels in Community-Acquired Pneumonia

Abstract

Community-acquired pneumonia (CAP) remains a major cause of morbidity and mortality worldwide, and early prediction of disease severity continues to represent a clinical challenge. This study aimed to evaluate the relationship between plasma D-dimer levels and CAP severity and clinical outcomes, and to compare its performance with the Pneumonia Severity Index (PSI).

The study included 100 patients with CAP and 35 healthy controls. Patients were stratified according to PSI risk classes.                               

 D-dimer levels were significantly higher in patients compared with controls (p < 0.001) and showed a moderate positive correlation with PSI scores (r = 0.652).                                                                                       

D-dimer levels increased progressively with greater disease severity and worse clinical outcomes, including the need for intensive care, empyema, and mortality (p < 0.001).                                                                           

In ROC analysis, D-dimer demonstrated excellent discriminative ability for predicting mortality (AUC = 0.992) and good performance in predicting severe complications, outperforming PSI in certain outcomes.

Conclusion: D-dimer levels are positively associated with CAP severity and adverse clinical outcomes. D-dimer may serve as a simple and rapid adjunctive biomarker to support early risk assessment and clinical decision making within an integrated clinical evaluation framework, with need for external validation studies.