Occupational asthma in the community: risk factors in a western Mediterranean population

Risk factors and prevalence of occupational asthma in the general population were examined in a cross-sectional community study conducted in north Barcelona. A self-administered questionnaire that contained questions about bronchial asthma and occupation was mailed to a random sample of 4000 adults who lived in north Barcelona; the response rate was 31.0%. Investigators made phone calls to nonresponders to determine response bias. Risk factors for occupational asthma were assessed with logistic regression. Investigators, who sought a definite diagnosis of occupational asthma, offered a chest examination to all subjects who reported asthma in life and who experienced clinically relevant occupational exposures. The examination included skin tests to common allergens, forced spirometry with reversibility test, and peak expiratory flow rate at and away from work. Cumulative prevalences obtained from responders were good estimates for the general population: asthma in life, 9.0%; clinically relevant occupational exposure, 28.9%; and respiratory symptoms at work, 18.3%. Adjustments were made for age, sex, and smoking habits, and relevant exposure caused an increase in asthma risk (odds ratio [OR] = 1.9; 95% confidence interval [95% CI] = 1.1, 3.2); however, when investigators introduced specific occupations in the model as independent variables, only occupational exposure to leather (OR = 12.8 [95% CI = 4.4, 37.4]), animals (OR = 10.3 [95% CI = 1.6, 65.2]), dyes (OR = 5.6 [95% CI = 2.1, 15.3]), and flour (OR = 4.6 [CI = 1.3, 15.7]) persisted as significant risk factors. A 1.7/1000 minimum prevalence of occupational asthma for the north Barcelona population was estimated from chest examination results. Occupational risk for asthma appeared to be associated with exposure to leather, animals, dyes, or flour in the north Barcelona area.