D-dimer as A Biomarker of Severity and Adverse Outcomes in Patients with Community Acquired Pneumonia

Community-acquired pneumonia (CAP) stands as a main cause of hospitalization and mortality worldwide. Because of their limitation scoring systems such as CURB-65 and Pneumonia Severity Index (PSI) may underestimate the severity of the disease. Intravascular and intra-alveolar activation of coagulation factors may lead to fibrin deposition in alveoli and lung interstitium. The clinical utility of D-dimer measurement in patients with CAP is still unclear. The aim of this study was to evaluate the association of D-dimer levels with severity of CAP, need for invasive mechanical ventilation, vasopressor support, and 7 d in-hospital mortality.

Prospective observational study from August 2016-November 2017 in a secondary care level hospital at Mexico City. CURB-65 and PSI scores were calculated on admission. D-dimer levels were measured by a fluorescence immunoassay.

A total of 61 adult patients with CAP were analyzed and categorized into low or high-risk groups using CURB 65 and PSI score. The average age was 71.6 ± 15 years, predominantly men (52%). Statistically significant higher D-dimer levels, vasopressor support, and mechanical ventilation were observed in high-risk groups. The AUC to predict 7 d in-hospital mortality was 0.93 (p <0.0001) for PSI, 0.853 (p = 0.01) for CURB 65, and 0.789 (p = 0.001) for D-dimer. A D-dimer cut-off point of 2400 mcg/L showed a sensitivity = 1 and a specificity = 0.614, as well as a positive predictive value = 0.154 and a negative predictive value = 1.

D-dimer plasma levels are associated with the severity of CAP. Patients with D-dimer below 2400 mcg/L have low probability of mortality at 7 d after admission to the emergency department.