Serum and urine galactomannan testing for screening in patients with hematological malignancies

Testing for serum galactomannan (GM) has been established as an important method for diagnosing invasive aspergillosis (IA); however, limited data exist regarding the application of urine GM testing. The objective of this study was to evaluate the performance of GM screening of urine specimens and to compare results with serum GM. The study was performed between July 2012 and March 2013 in adult patients with underlying hematological malignancies who were hospitalized at the Medical University of Graz, Austria. Serum and urine screening samples were collected and tested twice weekly (always on the same day). In total, 242 serum samples and a similar number of urine samples were collected from 75 patients. A total of 21/242 (8.7%) serum samples from 13 patients were GM positive. Sensitivity, specificity, positive predictive value, and negative predictive value using a 0.1 optical density index cutoff for urine samples (compared with same-day serum results) were as follows: 47.6%, 86%, 24.4%, and 94.5%, respectively. In 8/10 patients with probable IA, at least one positive GM result was found with this cutoff. After calculating clinical performance of the urine GM test, we found that sensitivity increased to 71.4% and specificity to 88.2%. Spearman-Rho correlation analysis revealed a significant positive correlation between serum and urine samples (P < 0.001; ρ = 0.252). In conclusion, GM detection in urine might be a promising method for IA screening. However, further studies are needed.