Socioeconomic, environmental and personal correlates of asthma in a community population of men and women.

Abstract

Asthma is a multifactorial chronic disease that has shown a marked increase in prevalence over the past few decades, both in Canada and worldwide. Basic knowledge gaps remain about the pathways through which risk factors influence adult asthma. More adult women than men have asthma, and a growing body of research suggests that associations between certain risk factors and asthma may differ by sex. The aim of this thesis was to investigate the socioeconomic, environmental and personal correlates of asthma in men and women.

Data for this thesis were obtained from a cross-sectional study conducted in 2003 in the rural Canadian town of Humboldt, Saskatchewan. The survey response rate was 71% of the resident target population, with 1177 females and 913 males aged 18 to 79 participating in the study. Researchers collected objective data on atopy (skin prick test), and body mass index. Exposures and history of physician-diagnosed asthma in the past year (current asthma) and during the participant’s lifetime (ever asthma) were self-reported. Multivariable logistic regression models adjusted for age, atopy, and parental asthma history were used to evaluate associations of correlates with asthma. The model building process was based on a conceptual framework of three categories: socioeconomic variables, home and work environment, and personal factors.

The prevalence of asthma was higher in women than men (ever asthma: 10.2% of women versus 5.8% of men; current asthma: 6.2% of women versus 2.8% of men). The logistic regression models for ever asthma and current asthma showed several sex differences. The sequential addition of each category of socioeconomic, environmental, and personal variables contributed significantly to model fit in women, but not in men. Living in a mobile, attached or multiple-family home, household dampness, and overweight/obesity were strong risk factors for female asthma, while farm living, occupational grain dust exposure, and regular alcohol use emerged as protective factors. Male models revealed a strong significant association between household dampness and current asthma. A significant interaction between home type and age was found only in females. Women living in homes other than single-family detached dwellings were more likely to have asthma, an association that decreased in strength with increasing age.

These results suggest that several risk factors for adult asthma may be sex-specific, therefore emphasizing the importance of considering sex as a potential effect modifier in future adult asthma epidemiology studies.