Diagnostic accuracy of pleural fluid polymorphonuclear elastase in the differentiation between pyogenic bacterial infectious and non-infectious pleural effusions.
OBJECTIVE
To establish the diagnostic accuracy of the markers of neutrophil activity (elastase and lysozyme) determined in pleural fluid, for differentiating between pyogenic bacterial infectious and non-infectious pleural effusions.


METHODS
At our tertiary referral teaching hospital, 160 patients over 14 years with pleural effusion (PE), classified as pyogenic bacterial infectious (41 parapneumonic complicated, 32 parapneumonic non-complicated) and non-infectious (32 neoplasm and 55 undiagnosed pleural exudates) were examined in a prospective study. Polymorphonuclear elastase (PMN-E) was determined by an immunoactivation method and lysozyme by a turbidimetric method. Receiver operating characteristic (ROC) curves were used to evaluate diagnostic accuracy.


RESULTS
Pleural fluid PMN-E was the biochemical marker that best differentiated between pyogenic bacterial infectious and non-infectious PE. The ROC area under the curve (AUC) for PMN-E was 0.8276. A PMN-E value over 230 microg/l diagnosed infectious PE with a specificity of 0.81 and a sensitivity of 0.74. The ROC AUC for proteins plus lactate dehydrogenase was 0. 7430. Differences between the two ROC curves were significant (p = 0. 032). After excluding purulent parapneumonic complicated PE, the sensitivity of a pleural fluid PMN-E value equal to or greater than 230 microg/l was 0.64 and the specificity 0.81.


CONCLUSIONS
Pleural fluid PMN-E was the marker that best differentiated infectious from non-infectious PE, and PMN-E values lower than 230 microg/l suggest non-infectious PE.
Service of Internal Medicine, General University Hospital Vall d'Hebrón, Barcelona, Spain. 18502jam@comb.es
J
J
Alegre
J M
JM
Suriñach
E
E
Varela
L
L
Armadans
R
R
Marti
R
R
Segura
C
C
Aleman
V
V
Falcó
T
T
Fernandez de Sevilla
D000293:Adolescent; D001424:Bacterial Infections / Q000150:complications* / Q000175:diagnosis* / Q000201:enzymology; D015415:Biomarkers; D001826:Body Fluids / Q000201:enzymology; D003937:Diagnosis, Differential; D006801:Humans; D019272:Leukocyte Elastase / Q000032:analysis*; D010994:Pleura / Q000201:enzymology; D010996:Pleural Effusion / Q000175:diagnosis* / Q000201:enzymology / Q000382:microbiology*; D013492:Suppuration / Q000209:etiology
D015415:Biomarkers; D019272:Leukocyte Elastase