The pattern of indoor and outdoor respiratory allergens in asthmatic adult patients in a humid and desert newly developed country.

BACKGROUND: Studies have shown that allergens are very important sensitizing agents in patients with asthma. Respiratory disorders such as asthma and allergic rhinitis are common in the State of Qatar.

OBJECTIVE: To characterize the most frequent indoor and outdoor respiratory allergens involved in bronchial asthma and allergic rhinitis in the State of Qatar.

DESIGN: A hospital-based prospective study conducted.

SETTING: Allergy Laboratory at the Hamad General Hospital and Hamad Medical Corporation, Doha, State of Qatar.

PATIENTS: Adult patients over 12 years of age diagnosed with bronchial asthma and/or allergic rhinitis who were referred for allergy skin pick test. 1106 adult patients recruited with respiratory diseases of suspected allergic origin who attended Allergy Clinic at the Hamad General Hospital, during three years from January 2001 to April 2003. Total of 1106 whom 607 were females (54.9%) and 499 were males (45.1%) and their mean was age 30 years (12-48).

METHODS: Skin Prick Test [SPT] was performed on 1106 patients for common allergens whom The blood sample was taken for measuring specific IgE concentration.

RESULTS: There were 1106 patients studied and 569 patients (51.4%) had positive skin prick test. All patients expressed clinical allergy, 464 patients (52%) had asthma and rhinitis, 286 patients (32%) had rhinitis alone and 137 patients (15%) had asthma alone. The population sample had a higher prevalence of diagnosed asthma among females (32.7%) than in males (29.8%) and also skin conditions such as eczema, pruritus, and urticaria higher in females (9.1%%) than males (7.0%). Similarly, males had higher prevalence of allergic rhinitis (86.0%) than in females. There were 318 (55.9%) patients whose asthma developed before they were 10 years old. The percentage of asthmatic patients with a positive family history of asthma was 44%. The most common allergens detected in order of frequency were Dermatophagoides Pteronyssimus (Der p l) in 248 patients (41.6%), Dermatophagoides Farinae (Der f l) in 220 patients (36.9%), Cockroach allergen (Bla g l) in 192 patients (32.2%). The study showed that females are more exposed to pollen, grasses and tress, but males are mostly exposed to mites and insects. Furthermore, Molds and Yeast were common among males.

CONCLUSION: In conclusion, the frequency of indoor and outdoor allergens in state of Qatar, based on skin prick test study showed the dominance of house dust mites, pollen, grasses which are more or less same to other countries with similar and even with different climate. Reduced exposure to these agents will help control raising severity of these disease.