Serum Aspergillus Galactomannan Lateral Flow Assay for the Diagnosis of Invasive Aspergillosis: A Single-centre Study

Background: Aspergillus species meet the most important group of invasive fungal diseases (IFD) in immunosuppressed patients. Galactomannan is a polysaccharide antigen located in the wall structure of Aspergillus. The most commonly used method for antigen detection is enzyme-linked immunoassay (ELISA). Aspergillus galactomannan lateral flow assay (LFA) constitutes one of the new methods in the diagnosis of invasive aspergillosis (IA). The goal of this study was to demonstrate efficacy of LFA in our patients and to compare it to synchronous ELISA results.

Methods: Galactomannan antigen was examined using both LFA and ELISA in serum samples taken from patients who were followed up in our haematology clinic. All patients are classified in subgroups as 'proven', 'probable' and 'possible' patients according to the last EORTC / MSG guideline. Patients who met the 'proven' IA criteria were included in the study as the gold standard.

Results: A total of 87 patients were included in the study. Majority of patients had acute myeloid leukaemia (AML) (56.3%). Eleven (12.6%) were in 'proven' IA group. LFA test showed a superior diagnostic performance compared with ELISA (LFA  = 0.934 vs ELISA  = 0.545; p < .001). The LFA had a sensitivity of 90.9% and a specificity of 90.8% for '0.5 ODI' in predicting IA (PPV = 55.8%; NPV = 98.6%; p < .001).

Conclusion: The most important finding of this study is that the specificity of LFA was found to be higher for cut-off value of 0.5. It is recommended to combine the methods in many studies to provide a better early diagnosis for IA.