Efficacy of LD BioAspergillus ICT Lateral flow assay for serodiagnosis of chronic pulmonary aspergillosis

Abstract

Background: The diagnosis of CPA relies on the detection of IgG Aspergillus antibody which is not freely available, especially in resource-poor settings. Point-of-care tests like LDBio Aspergillus ICT lateral flow assay, evaluated in only a few studies, have shown promising results for diagnosis of CPA. However no study has compared the diagnostic performances of LDBio LFA in setting of tuberculosis endemic countries and have compared it with that of IgG Aspergillus. Objectives: This study aimed to evaluate the diagnostic performances of LDBio LFA in CPA and compare it with existing diagnostic algorithm utilising ImmunoCAP IgG Aspergillus. Methods: Serial patients presenting with respiratory symptoms (cough, hemoptysis, fever etc) for > 4 weeks were screened for eligibility. Relevant investigations including direct microscopy and culture of respiratory secretions, IgG Aspergillus, chest imaging etc were done according to existing algorithm. Serum of all patients were tested by LDBio LFA and IgG Aspergillus (ImmunoCAP Asp IgG) and their diagnostic performances were compared. Results: A total of 174 patients were included in the study with ~66.7% patients having past history of tuberculosis. A diagnosis of CPA was made in 74 (42.5%) of patients. The estimated sensitivity and specificity of LDBio LFA was 67.6% (95% CI: 55.7%- 78%) and 81% (95% CI: 71.9%-81%) respectively which increased to 73.3% (95% CI: 60.3%-83.9%) and 83.9% (95% CI: 71.7%-92.4%) respectively in patients with past history of tuberculosis. The sensitivity and specificity of IgG Aspergillus was 82.4% (95% CI: 71.8%-90.3%) and 82% (95% CI: 73.1-89%); 86.7% (95% CI: 75.4%-94.1%) and 80.4% (95% CI: 67.6%-89.8%) in the whole group and those with past history of tuberculosis respectively. Conclusions: LDBio LFA is a point-of-care test with reasonable sensitivity and specificity. However, further tests may have to be done to rule-in or rule-out the diagnosis of CPA in the appropriate setting.