Cut-off values of serum IgE (total and A. fumigatus -specific) and eosinophil count in differentiating allergic bronchopulmonary aspergillosis from asthma

Authors

  • Ritesh Agarwal,

    Corresponding author
    1. Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
    • Correspondence: Dr R. Agarwal, Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012, India.

      Tel.: +91 172 2756825. Fax: +91 172 2748215.

      E-mail: riteshpgi@gmail.com

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  • Ashutosh N. Aggarwal,

    1. Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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  • Mandeep Garg,

    1. Department of Radiodiagnosis, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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  • Biman Saikia,

    1. Department of Immunopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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  • Arunaloke Chakrabarti

    1. Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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Summary

The cut-off values of immunological tests employed in diagnosis of allergic bronchopulmonary aspergillosis (ABPA) have never been validated. Herein, we compare the immunological findings in patients with ABPA and asthma using receiver operating characteristic analysis. Consecutive asthmatic subjects underwent all the following investigations: Aspergillus skin test, IgE levels (total and Afumigatus-specific), Aspergillus precipitins, eosinophil count, chest radiograph and CT chest. There were 372 subjects (179 men, mean age 35.9 years) with a mean asthma duration of 8 years. ABPA was diagnosed in 76 patients (64 bronchiectasis, 12 without bronchiectasis). ABPA was separated from asthma using the best cut-off values of total IgE, A. fumigatus IgE and total eosinophil count of 2347 IU ml−1, 1.91 kUA l−1 and 507 cells per μl respectively. The sensitivity/specificity of these parameters were 87/81%; 99/87%; and, 79/76% respectively. The corresponding AUC values were 0.95, 0.90 and 0.82 respectively. The combination of these three tests at the aforementioned cut-offs provided 100% specificity. Our study provides evidence-based cut-off values of IgE (total and A. fumigatus-specific) and eosinophil counts in differentiating ABPA from asthma. As this is a single centre retrospective study, further studies from different centres are required, as these values could vary by ethnicity and environmental exposure.

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