Allergy, occupational exposures, and incidence of COPD in SAPALDIA

Introduction: Whether allergy may be a susceptibility factor of chronic obstructive pulmonary disease (COPD) in association with occupational respiratory irritants is unknown. We evaluated interactions between markers of underlying allergy and occupational exposures on risk of COPD in the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA). Methods: Pre-bronchodilator ratio of forced expiratory volume in one second over forced vital capacity (FEV1/FVC) was measured in 3,547 SAPALDIA participants' ages 18-62 who participated at baseline in 1991 and follow-up in 2001-2003. Participants reporting occurrence of asthma or wheezing without cold, or presenting with airflow obstruction at baseline were excluded from the analysis. COPD was defined according to the spirometric reference equations (FEV1/FVC100 kU/l). We evaluated two-way interactions between each allergic marker and occupational exposure separately in mixed Poisson regression models of incident COPD after adjustment for potential confounders. Results: Statistically significant interactions (p