Characteristics of studies included in the meta-analysis.

ICU, intensive care unit; C, clinical; R, radiological; M, microbiological; PR, prospective recruitment; NA, not available; CAP, community acquired pneumonia; VAP, ventilator associated pneumonia; HAP, hospital acquired pneumonia; BALF, bronchoalveolar lavage fluid; CFU, colony-forming units; PSB, protected specimen brush; ELISA, enzyme-linked immunosorbent assay; TP, true-positive; FP, false-positive; FN, false-negative; TN, true-negative.