Gender Differences in the Association of Individual and Contextual Exposures with Lung Function in a Rural Canadian Population.

INTRODUCTION: To investigate the association of individual and contextual exposures with lung function by gender in rural-dwelling Canadians.

METHODS: A cross-sectional mail survey obtained completed questionnaires on exposures from 8263 individuals; a sub-sample of 1609 individuals (762 men, 847 women) additionally participated in clinical lung function testing. The three dependent variables were forced expired volume in one second (FEV1 ), forced vital capacity (FVC), and FEV1 /FVC ratio. Independent variables included smoking, waist circumference, body mass index, indoor household exposures (secondhand smoke, dampness, mold, musty odor), occupational exposures (grain dust, pesticides, livestock, farm residence), and socioeconomic status. The primary analysis was multiple linear regression, conducted separately for each outcome. The potential modifying influence of gender was tested in multivariable models using product terms between gender and each independent variable.

RESULTS: High-risk waist circumference was related to reduced FVC and FEV1 for both genders, but the effect was more pronounced in men. Greater pack-years smoking was associated with lower lung function values. Exposure to household smoke was related to reduced FEV1 , and exposure to livestock, with increased FEV1 . Lower income adequacy was associated with reduced FVC and FEV1 .

CONCLUSION: High-risk waist circumference was more strongly associated with reduced lung function in men than women. Longitudinal research combined with rigorous exposure assessment is needed to clarify how sex and gender interact to impact lung function in rural populations.