Accuracy of BAL galactomannan and Aspergillus-PCR in diagnosing chronic pulmonary aspergillosis

Background: The role of serum/bronchoalveolar lavage(BAL) galactomannan and BAL fungal polymerase chain reaction(PCR) is not clear in diagnosis of chronic pulmonary aspergillosis(CPA) as the diagnostic algorithm for CPA has not consistently employed them. Objective: This study aimed to evaluate the role of Aspergillus BAL/serum galactomannan in diagnosis of CPA and compare it with existing diagnostic algorithm using ImmunoCAP IgG Aspergillus. Methodology: This was a prospective observational study done over 2 years on consecutive treament-naive subjects being evaluated for CPA.  Aspergillus PCR was evaluated by AsperGenius® and in-house PCR, while galactomannan was assayed by Platelia® Aspergillus AG 96T. A cut-off of 0.5 was used for both serum and BAL galactomannan. All patients were subjected to evaluation by BAL (for ruling out of alternative diagnoses e.g tuberculosis and other microbial infections) and IgG Aspergillus estimation by ImmunoCAP. While the patients fulfiling the diagnosis of CPA served as subjects, those patients of CPA suspects not fulfilling the diagnosis of CPA, served as controls. Results: In total , 218 patients(age:39+14 years, 54 % males) suspected of having CPA, were included in this study. In total, 41% had a diagnosis of CPA by ERS/ESCMID criteria. The calculated sensitivity/ specificity of BAL galactomannan, serum galactomannan, AsperGenius® and in-house PCR were  54%/69%, 31%/79% 51%/30% and 53%/31% respectively. Conclusions: This study showed that BAL/serum galactomannan had better diagnostic accuracy than BAL PCR in the diagnosis of CPA. While the sensitivity was comparable, the specificity of BAL galactomannan was higher than BAL fungal PCR in CPA patients.