S2 Occupational exposure, breathlessness and COPD in a general population of older UK men
Most COPD is attributable to smoking, however evidence from workforce and general population studies suggest that occupational exposure is also associated with the disease. This study examines the relationship between respiratory symptoms, doctor-diagnosed COPD and occupational exposure in a general UK population. Lifetime occupational and smoking history, doctor-diagnosed disease and current respiratory symptoms were collected by postal questionnaire in a cohort of subjects aged 51–60, recruited from 33 general practices in Kent; here we present the results in men (n=3011). Occupations were defined a priori as being associated with an increased risk of COPD using 13 job categories as defined for the European Community Respiratory Health Survey1; all other occupations were designated low risk (referent). Logistic regression in men with complete data and no history of asthma (n=2452) demonstrated a statistically significant increase in both the odds of breathlessness (modified MRC score 1 or greater, Abstract S2 table 1) and breathlessness reported along with symptoms of chronic bronchitis (data not shown) in subjects who had a history of ever having been employed in a risky job, compared to other referent (mainly white collar) workers. This association, between work in occupations with an a priori risk of COPD and chronic respiratory symptoms, remained after adjustment for age and smoking status, using pack year history. The strength of the relationship between symptoms and work varied by occupational type; cleaners, painters and agricultural workers had the highest risk of breathlessness when compared to the referent population (Abstract S2 table 1). An increased risk of doctor-diagnosed COPD (COPD, chronic bronchitis or emphysema) was also found in cleaners, transport workers, wood and construction workers (data not shown); in comparison with the prevalence of respiratory symptoms, the number of men declaring doctor-diagnosed disease was small (21% vs 5%). This study demonstrates an association between occupational exposure, chronic respiratory symptoms and doctor-diagnosed COPD within a general population of older males in the UK independent of smoking history. Further characterisation of the cohort, using the results of spirometry, will allow the relationship between risky job exposure and disease to be examined in more detail.