Diagnostic performance of-specific immunoglobulin G immunochromatographic and enzyme-linked immunosorbent assay testing in chronic pulmonary aspergillosis: comparative analysis across subtypes and influencing factors.

BACKGROUND: Elevated serum-specific immunoglobulin G (IgG) is a key diagnostic criterion for chronic pulmonary aspergillosis (CPA). This study evaluated the diagnostic performance of-specific IgG testing, comparing rapid immunochromatographic point-of-care test (ICT-POCT) with enzyme-linked immunosorbent assay (ELISA) for CPA and its subtypes, while identifying factors influencing test accuracy.

METHODS: We recruited 112 CPA patients and 61 non-CPA controls with pulmonary diseases from The First Affiliated Hospital of Guangzhou Medical University between December 2021 and November 2022. CPA diagnosis followed composite clinical, radiological, and microbiological criteria. Serum-specific antibodies were analyzed using quantitative ELISA (IgG) and ICT [IgG/immunoglobulin M (IgM)]. Bronchoalveolar lavage (BAL)galactomannan (GM) was tested where available. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.

RESULTS: 90% of CPA patients had elevated-specific IgG antibodies by ImmunoCAP. ICT assay demonstrated superior overall diagnostic performance (sensitivity: 88.4%; specificity: 95.1%). ELISA [58.9% sensitivity, 82.0% specificity at 80 arbitrary units per milliliter (AU/mL) cut-off]. Combined testing achieved peak specificity (98.4%) but reduced sensitivity. individual tests. Among patients with a history of antifungal treatment, the sensitivity of ICT assay varied by subtypes: 78.6% for chronic cavitary pulmonary aspergillosis (CCPA), 57.1% for chronic fibrosing pulmonary aspergillosis (CFPA), 66.7% for simple aspergilloma (SA), 66.7% for subacute invasive aspergillosis (SAIA), and 50% fornodule(s) (AN). In addition, the sensitivity of the ICT assay differed in comorbidities: 76.5% in patients with chronic obstructive pulmonary disease (COPD), 97.3% in patients with bronchiectasis, and 96.7% in patients with cavitary pulmonary tuberculosis. Notably, prior antifungal and steroid therapy decreased the performance of both assays.

CONCLUSIONS: The-specific IgG ICT assay shows significant diagnostic value for CPA, particularly in untreated patients and CCPA subtype. Its high specificity and rapid format position it as a valuable point-of-care tool for prompt CPA diagnosis in resource-limited settings.