@article {Dumas603, author = {Orianne Dumas and Nicole Le Moual and Val{\'e}rie Siroux and Dick Heederik and Judith Garcia-Aymerich and Rapha{\"e}lle Varraso and Francine Kauffmann and Xavier Basaga{\~n}a}, title = {Work related asthma. A causal analysis controlling the healthy worker effect}, volume = {70}, number = {9}, pages = {603--610}, year = {2013}, doi = {10.1136/oemed-2013-101362}, publisher = {BMJ Publishing Group Ltd}, abstract = {Objectives The healthy worker effect usually leads to underestimation of the association between occupational exposure and asthma. The role of irritants in work-related asthma is disputed. We estimated the effect of occupational exposure on asthma expression in a longitudinal study, using marginal structural modelling to control for the healthy worker effect. Methods Analyses included 1284 participants (17{\textendash}79 years, 48\% men) from the follow-up (2003{\textendash}2007) of the French Epidemiological study on the Genetics and Environment of Asthma (case-control study). Age at asthma onset, periods with/without attacks over lifetime and occupational history were recorded retrospectively. Exposures to known asthmagens, irritants or low level of chemicals/allergens were evaluated through a job-exposure matrix. The job history was reconstructed into 5-year intervals. Results Thirty-one per cent of subjects had ever been exposed to occupational asthmagens. Among the 38\% of subjects who had asthma (ever), presence of attacks was reported in 52\% of all time periods. Using standard analyses, no association was observed between exposure to known asthmagens (OR (95\% CI): 0.99 (0.72 to 1.36)) or to irritants/low level of chemicals/allergens (0.82 (0.56 to 1.20)) and asthma attacks. Using a marginal structural model, all associations increased with suggestive evidence for known asthmagens (1.26 (0.90 to 1.76)), and reaching statistical significance for irritants/low level of chemicals/allergens (1.56 (1.02 to 2.40)). Conclusions The healthy worker effect has an important impact in risk assessment in work-related asthma studies. Marginal structural models are useful to eliminate imbalances in exposure due to disease-driven selection. Results support the role of irritants in work-related asthma.}, issn = {1351-0711}, URL = {https://oem.bmj.com/content/70/9/603}, eprint = {https://oem.bmj.com/content/70/9/603.full.pdf}, journal = {Occupational and Environmental Medicine} }