Bronchoalveolar Lavage Fluid Galactomannan for the Diagnosis of Invasive Pulmonary Aspergillosis in Patients with Hematologic Diseases

Abstract

Prompt diagnosis of invasive pulmonary aspergillosis (IPA) remains a challenge. Galactomannan (GM) detection in bronchoalveolar lavage (BAL) fluid by the Platelia enzyme immunoassay aims to further improve upon the test's utility by applying it directly to specimens from the target organ. A retrospective analysis of the Platelia assay was performed on BAL samples from 99 evaluable high-risk hematology patients, including 58 with proven or probable IPA. BAL GM demonstrated an improved sensitivity profile (91.3% with an optical density [OD] index cutoff of >or=1.0) in comparison with culture and microscopy (50% and 53.3%, respectively). The diagnostic accuracy as given by the area under the receiver operating characteristic curve was 0.93 (95% confidence interval, 0.88-0.99); further decreasing the OD index cutoff to 0.5 compromised specificity more than it improved sensitivity. Estimates of the positive and negative predictive value of the Platelia assay on BAL samples (OD index, >or=1.0) were 76% and 96%, respectively. The mean BAL GM OD index was not different in neutropenic versus nonneutropenic case patients (3.9 and 4.5, respectively; P = .3); however, a trend toward decreased sensitivity in patients receiving mold-active prophylaxis was noted. BAL GM is a valuable adjunctive diagnostic tool to other conventional microbiologic and radiologic studies.