Methods: All patients with asthma underwent immediate cutaneous testing including prick (epicutaneous) with a mix of Aspergillus species and if negative, intradermal at 1000 PNU/mL, Aspergillus fumigatus (Af). Sera were analyzed for total IgE (elevated is ≥ 417 kU/L) by Phadia ImmunoCap, anti-Af IgE and anti-Af IgG (ABPA range ≥ 2.0) ELISA, and precipitating antibodies. HRCT of the lungs was ordered next if serology was positive (diagnostic criteria for ABPA required total IgE ≥ 417 kU/L and both anti-Af IgE and IgG ≥ 2.0 compared to sera from skin test + patients with asthma without ABPA). To avoid bias from patients examined by the author, data were compared using screening from 5 other faculty in the same clinic.
Results: From 2000-2010, 864 skin test + patients underwent serologic testing for ABPA from which 81 (9.4%) were diagnostic for ABPA, and in this group, precipitins were positive in 42/81. To address referral bias in screened patients of the author, diagnostic criteria were positive in 49/208 (23.5%) patients of the author vs. 32/656 (4.8%) of other allergy-immunology faculty. In addition, some 74/884 (8.6%) patients had total IgE ≥ 417 kU/L and either anti-Af IgE or IgG ≥ 2.0, implying an overall at risk for ABPA population of 155/864 (17.9%). The highest total IgE recorded in a non-ABPA patient with asthma was 192,100 kU/L.
Conclusions: : Using total IgE and ELISA determinations to discriminate ABPA from skin test + asthma sera, 9.4% of patients had diagnostic evidence for APBA. Using data from faculty, presumably with less referral bias than the author, results in 4.8% patients with classic diagnostic criteria. This rate conservatively translates into a minimum of approximately 1.2% of patients with persistent asthma having APBA in the upper Midwestern US. The combination of elevated total IgE and precipitins but not elevated anti-Af IgE or IgG in this population has little/no value in diagnosis