Establishment of Aspergillus fumigatus-specific IgG cut-off level for diagnosis of chronic pulmonary aspergillosis in the Iranian population

Background and Purpose: The optimal cut-off level for serum Aspergillus-specific IgG (SAfIgG) in the diagnosis of chronic pulmonary aspergillosis (CPA) remains to be established for different countries. This study aimed to establish a cut-off level for SAfIgG in CPA diagnosis and validate its diagnostic accuracy in the Iranian population. Materials and Methods: Diagnostic performance of SAfIgG was evaluated in patients with chronic obstructive pulmonary disease (COPD) suspected of having CPA who had referred to the two reference centers for pulmonary diseases in Iran, during ۲۰۲۱-۲۰۲۳. Levels of SAfIgG were measured using an enzyme-linked immunosorbent assay. Optimal cut-off point for SAfIgG was determined using the receiver operating characteristics (ROC) curve and Youden's index and was subsequently validated. Results: In total, ۳۰ (۱۵.۳%) out of ۱۹۶ COPD patients were diagnosed with CPA. The ROC curve analysis yielded an area under the curve of ۰.۶۳۲ (۹۵% CI: ۰.۴۲۱-۰.۸۴۳; p=۰.۱۱۴), with an optimal cut-off value of ۲۳.۵ U (sensitivity: ۷۱.۴%; specificity: ۶۱.۴%). The SAfIgG levels were significantly higher in CPA patients (median [IQR], ۳۹ [۳۱-۵۵] U) compared with non-CPA patients (۲۰ [۱۵-۲۴] U; p<۰.۰۰۱). Conclusion: The findings indicated that SAfIgG, with a cut-off value of ۲۳.۵ U, provided moderate sensitivity and specificity for screening and may be used in combination with the culture method to confirm the diagnosis of CPA in COPD patients. However, the variability in cut-off values across different populations highlights the need for standardized guidelines to improve diagnostic consistency and reliability.

کلیدواژه ها:

Aspergillus fumigatus ، Chronic obstructive pulmonary disease ، IgG