Why despite the lower prevalence, is asthma more severe in the semiarid region?

Abstract

Introduction and objectives: Asthma is a chronic inflammatory disease which is very prevalent throughout the world, and climatic factors, especially air humidity, have been considered fundamental to its development. This study aims to evaluate the relationship between the climate factor and the severity of asthma episodes in the semiarid region, comparing it to the coast and an intermediate climate region, considering the use of medication as an intervening factor.

Materials and methods: Ecological study in cities with different climatic conditions (semiarid, intermediate region and Coast). Prevailing data was obtained from the International Study of Asthma and Allergies in Childhood (ISAAC) protocol. We evaluated the temperature, humidity and use of drugs for asthma/100,000 inhabitants.

Results: The prevalence of asthma was lower in the semiarid (14%; 95%CI=12.1-15.7) than the intermediate region (19.1%; 95%CI=17.7-20.6) and coast (17.9%; 95%CI=16.6-19.2). Episodes of severe asthma attacks were surprisingly higher in semiarid (10.4%; 95%CI=8.9-11.9) when compared to coast (4.1%; 95%CI=3.4-4.9) and intermediate region (5.0%; 95%CI=4.3-5.8). In the semiarid region, the humidity was lower and the temperature higher than the other cities evaluated. The dispensing of medications was lower in the semiarid region.

Conclusions: Temperature and humidity may have contributed to a lower prevalence and greater severity of asthma in the semiarid region. The dispensing of medications was lower in the semiarid region, indicating that access to both relief and control drugs was lower in this city. The possibility of lack of health care in the semiarid region can also be another explanatory factor associated.

Keywords: Asthma; Climate; Drug Administration Schedule; Ecological study; Epidemiology.