Diagnostic Performance of Aspergillus-Specific Immunoglobulin G Testing in Chronic Pulmonary Aspergillosis, Its Subtypes, and Influencing Factors

Presence of elevated serum Aspergillus-specific IgG is an integral diagnostic criterion for CPA. The study aimed to compare the diagnostic performance of rapid ICT-POCT with ELISA in diagnosing CPA and its subtypes, and to identify factors influencing these methods. A total of 112 CPA cases and 61 control patients were included. We found that 90% of CPA patients had elevated Aspergillus antibody levels by ImmunoCAP, while the ICT assay demonstrated a sensitivity of 88.4% and a specificity of 95.1% for diagnosing CPA overall. In contrast, the ELISA showed lower sensitivity at 58.9% but higher specificity at 82.0% for all CPA patients. The combination of both assays yielded the highest specificity (98.4%) but reduced sensitivity. For specific CPA subtypes, the sensitivity of the ICT assay was 78.6% for CCPA, 57.1% for CFPA, 66.7% for SA, 66.7% for SAIA, and 50% for AN, respectively, in patients who had previously received antifungal treatment. In addition, the sensitivity of the ICT assay was 60.0% in patients with COPD who had previously received glucocorticoid therapy, 97.3% in patients with bronchiectasis, and 96.7% in patients with cavitary pulmonary tuberculosis, respectively. Notably, prior antifungal and steroid therapy decreased the performance of both assays. In conclusion, Aspergillus-specific IgG testing offers significant diagnostic value in CPA, especially for the CCPA subtype. The ICT assay demonstrates superior sensitivity compared to ELISA, making it a valuable tool for prompt diagnosis, particularly in resource-limited settings. However, prior antifungal and glucocorticoid therapy impact the diagnostic performance of both assays.