Admission D-dimer can identify low-risk patients with community-acquired pneumonia.

Study Objective: Severity assessment is an important component of the management of community-acquired pneumonia. Clinicians are increasingly searching for biomarkers to aid in clinical decisions. Coagulation disorders can accompany severe pneumonia. We seek to investigate the association of D-dimer, a fibrinolysis biomarker, and 30-day mortality or the need for mechanical ventilation or vasopressor support in emergency department (ED) patients with community-acquired pneumonia.

Methods: We prospectively enrolled ED patients with community-acquired pneumonia between December 2005 and January 2008 in a convenience manner. We measured D-dimer level with the Vitek ImmunoDiagnostic Assay System. To assess clinical illness severity, both CURB65 and the Pneumonia Severity Index (Pneumonia Severity Index class) were calculated. Our primary outcomes were 30-day mortality and need for mechanical ventilation or vasopressor support.

Results: Of the 314 enrolled patients, 23.9% of patients had a D-dimer level less than 500 ng/mL on initial ED measurement, and 81.3% of these patients were in Pneumonia Severity Index class I to III. A D-dimer level of less than 500 ng/mL had a negative likelihood ratio of 0 (95% confidence interval 0 to 1.37) for 30-day mortality and 0.33 (95% confidence interval 0.09 to 1.27) for need for mechanical ventilation or vasopressor support. For 30-day mortality, the area under the receiver operator characteristic curve for D-dimer was similar to both CURB65 and Pneumonia Severity Index class. For mechanical ventilation or vasopressor support, the area under the receiver operator characteristic curve for D-dimer was lower than that for CURB65 but did not differ from that for Pneumonia Severity Index.

Conclusion: An admission D-dimer level less than 500 ng/mL is associated with low risk of short-term death and major morbidity in patients with community-acquired pneumonia.