Sensitization of Severe Allergic Asthma Patients

Background: The prevalence of asthma is high, the worldwide average being estimated at 10%, which makes it a public health problem. Many studies show a clear relationship between asthma and specific allergens. With sensitization to aeroallergens  identified as a dominant risk factor for asthma. Objective: The present study of asthma reports the allergic sensitization of patients with severe persistent asthma  followed  in the Division of Clinical Immunology and Allergy of University of São Paulo Medical School.

Methods: A total of 61 patients with severe persistent asthma defined according to the criteria of the Global Initiative for Asthma (GINA) were enrolled. Total IgE levels (IU/mL) were measured in serum and levels up to 120 IU/mL were considered within normal range. A battery of 7 aeroantigens (Dermatophagoides pteronyssinus, Blomia tropicalis, Aspergillus fumigatus, Penicillium nonatum, Lolium perenne, Felis domesticus, Canis familiaris, Blatela germanica and Periplaneta americana) was used in skin prick tests (SPTs), which were performed in each subject, on the volar side of the forearm. Histamine hydrochloride and normal saline solutions were used as positive and negative controls, respectively. The SPTs were read after 15 minutes and, a wheal at least 3 mm greater than the negative control was considered positive.

Results: The asthmatic patients had a mean age of 48 years and 75% were female. We found that mean total serum IgE levels were 518.4 IU/mL (between 17 and 4720 UI/mL). SPTs positivity was 91.8% for D pteronyssinus, 67.2% for Blomia tropicalis, 4.9% for P nonatum and A fumigatus, 6.5% L perene and Felis domesticus, 16.3% for Canis familiaris,  21.3% Blatela germanica, 13.1% for Periplaneta americana. Twelve patients were monosensitized and 23 patients were polysensitized to 3 or more allergens.

Conclusions: Most patients with severe allergic asthma were polysensitized, and dust mites, followed by cockroaches, were the main allergens.