Aspergillus fumigatus-specific IgG is pivotal in making the diagnosis of chronic pulmonary aspergillosis (CPA). However, the cut-off value for A. fumigatus-specific IgG remains unknown. We included consecutive treatment-naïve subjects with chronic cavitary pulmonary aspergillosis (CCPA, cases). The controls were subjects with treated pulmonary tuberculosis, who had residual radiological abnormality and minimal symptoms. The diagnosis of CCPA was based on consistent clinicoradiological features along with demonstration of Aspergillus infection (growth of Aspergillus in sputum or bronchoalveolar lavage fluid [BALF] culture; serum or BALF galactomannan index >0.5 and >1, respectively). For determining the cut-off of A. fumigatus-specific IgG (Phadia), subjects were randomly classified as derivation (two-thirds) and validation (one-third) cohort. One hundred and thirty-seven cases and 50 controls were included. The best cut-off value for A. fumigatus-specific IgG (derivation cohort) was 27.3 mgA/L (AUROC, 0.976) at a sensitivity and specificity of 95.6% and 100%, respectively. Using a cut-off of 27 mgA/L, the sensitivity and specificity in the validation cohort was 91.3% and 100%, respectively. In contrast, the sensitivity of Aspergillus precipitins was only 25.5%. At a cut-off value of 27 mgA/L, A. fumigatus-specific IgG is a reliable test with high sensitivity and specificity in the diagnosis of CPA. More studies are required to confirm our findings.

Few studies have evaluated the utility of Aspergillus fumigatus-specific IgG in allergic bronchopulmonary aspergillosis (ABPA). Herein, we evaluate the role of specific IgG in diagnosis and monitoring treatment response in ABPA. Forty-eight control subjects with A. fumigatus-associated asthma underwent A. fumigatus-specific IgG measurements at baseline, while specific IgG was assayed in 102 treatment-naïve subjects of ABPA at baseline, after eight weeks of glucocorticoid therapy, and during exacerbations. For determining the cut-off of A. fumigatus-specific IgG, we randomly classified two-thirds of the study subjects (cases and controls) as the derivation cohort, while the remaining one-thirds were labelled as the validation cohort. The best cut-off value of A. fumigatus-specific IgG in the derivation cohort was 26.9 mg /L (sensitivity: 88%; specificity: 100%). Using this limit, the sensitivity and specificity of A. fumigatus-specific IgG in diagnosis of ABPA was 89% and 100%, respectively, in the validation cohort. In contrast, the sensitivity of Aspergillus precipitins was only 27.4%. Following treatment, the A. fumigatus-specific IgG increased in 38 (37.2%) subjects, while it decreased in three (23.1%) of the 13 subjects experiencing an exacerbation. The A. fumigatus-specific IgG was found to be an extremely useful test in the diagnosis and differential diagnosis of ABPA but is unreliable in monitoring treatment response in this disorder.

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The value of serum and bronchoalveolar lavage fluid galactomannan (BALF-GM) in diagnosing chronic pulmonary aspergillosis (CPA) remains unclear. Here, we study the diagnostic efficacy of GM in the diagnosis of CPA. We included consecutive treatment-naive subjects with CPA. For calculating the specificity of serum GM, we enrolled diseased controls (minimally symptomatic subjects previously treated for pulmonary tuberculosis, not meeting the criteria for CPA). To calculate the specificity of BALF-GM, subjects with pulmonary disorders other than CPA who underwent bronchoscopy were included. We determined the cutoff of serum and BALF-GM levels using receiver operating characteristic (ROC) curve analysis. We enrolled 243 consecutive treatment-naive subjects (53.5% males) of CPA with a mean (standard deviation) age of 43.6 (14.7) years. Forty-five (60% males; age, 46.7 [15.7] years) and 27 (59.3% males; age, 52.6 [12.8] years) subjects served as controls for serum and BALF-GM, respectively. The best cutoff value for serum and BALF-GM was 0.55 (area under the ROC curve [AUROC], 0.605; sensitivity, 38%; specificity, 87%) and 1.375 (AUROC, 0.836; sensitivity, 68%; specificity, 93%), respectively. At a cutoff value of 2.5, BALF-GM had a sensitivity and specificity of 50% and 100%, respectively. BALF-GM performs better than serum GM and may be helpful in the diagnosis of CPA in selected patients. More studies are required to confirm our findings.

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