Risk factors for development of asthma in Thai adults in Phitsanulok: a university-based study.

Studies have shown that asthma in children is caused by environmental and genetic factors. In adult asthma, risk factors were less well recognized. Likewise, in Thailand, data in adult asthma is limited. This study aimed to evaluate risk factors, determine skin reactivities to allergens, and assess concomitant allergy among adult asthma in Phitsanulok, a major city in the lower northern Thailand. Five hundred and thirteen Naresuan University staff members and students completed 2 sets of questionnaires and underwent allergy skin prick tests. The first set of questionnaires was standardized Thai version of ISAAC questionnaire for identifying asthma, allergic rhinitis, and atopic eczema. The second set was modified from ISAAC phase II questionnaire to identify asthma risk factors. Fifty-eight subjects (11.6%) were identified as having physician's diagnosed asthma and 89 subjects (17.7%) wheezed in the past 12 months. Among 89 subjects, 14.4% wheezed more than once a month, 45.6% had wheezes interfering with sleep. Concomitant allergic rhinitis, rhinoconjunctivitis and atopic eczema among these asthma subjects were 82.5%, 67.9%, and 14.9%, respectively. Eighty seven point nine percent of asthmatic subjects had positive skin reactivities to at least one allergen. Two of the most common allergens were house dust mites and cockroaches. Maternal smoking during pregnancy, smoking among family members, and family history of allergy were statistically significant risks for developing asthma, while having a rice field around the residence represented a significant protective factor. In conclusion, high prevalence of asthma presented in Phitsanulok and many asthmatic subjects were partly controlled or uncontrolled. The environment such as a rice field could protect against asthma, however atopy and smoking exposure were significant risks for asthma development