Introduction: IgE levels have been associated with asthma, but few studies have investigated their role in COPD. We investigated the differences in serum total (tIgE) and specific IgE (sIgE) between COPD, asthma and controls and associated atopy and allergy with acute exacerbations of COPD (AECOPD).
Materials and Methods: The derivation cohort consisted of 73 COPD patients, 19 asthma patients and 27 controls. The confirmation cohort consisted of 342 COPD patients. Serum samples were obtained and tIgE and 300 sIgEs were determined using the ALEX2 Allergy Explorer. Patients were considered atopic when tIgE? 100 kUA/L and allergic when their skin prick test was positive.
Results: In the derivation cohort, asthmatic patients presented the highest sIgE concentrations (p=0.005). In the confirmation cohort, allergic COPD patients had a higher number of AECOPD per year (p=0.043). COPD patients that were positive to at least one skin-prick-test aeroallergen demonstrated a higher risk for AECOPD in comparison to negative patients (43.40% vs 28.77%, p=0.035). However, sIgE levels were higher in those without AECOPD as compared to those that suffered an AECOPD in the previous year [median (IQR) sum of aeroallergens: 4.94 (3.41-10.98) kUA/L vs 2.98 (1.79-4.87) kUA/L, p<0.001 / median (IQR) sum of non-aeroallergens: 2.20 (1.11-10.06) kUA/L vs 1.36 (0.61-2.37) kUA/L, p=0.001)]. There was a positive association between time to AECOPD during the study and tIgE level (p= 0.020).
Conclusions: Asthmatic patients were more commonly atopic than COPD patients. In COPD, allergy seems to have a negative effect on the occurrence of AECOPD, while atopy seems not to be associated with an increased risk of AECOPD.