PURPOSE: Soluble Triggering Receptor Expressed on Myeloid cells-1 (sTREM-1) has proven to be a good biomarker for sepsis. For the diagnosis ventilator-associated pneumonia (VAP), however, there have only been a few, relatively small, studies on the role of this receptor. The aim of the study was to evaluate the usefulness of sTREM-1 in bronchoalveolar lavage fluid (BALF) from Intensive Care Unit patients as rapid diagnostic test for VAP. METHODS: The concentration of sTREM-1 in 240 BALF samples was measured using a quantitative sandwich enzyme immunoassay. Two researchers who were blind to the assay results determined whether a VAP was present or not. Clinical suspicion of a VAP was confirmed by the presence of > or = 2% cells containing intracellular organisms and/or a quantitative culture result of > or = 10(4) colony forming units per millilitre BALF. RESULTS: The mean concentration of sTREM-1 was significantly higher in the BALF of patients with confirmed VAP than in that of patients without confirmed VAP. However, the area under the receiver-operating characteristic curve was 0.58 (95% confidence interval 0.50-0.65, P = 0.04). CONCLUSIONS: The results imply that the sTREM-1 assay in BALF may not be discriminative for VAP.