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OP0145 Gene-environment and disease interactions: is it smart to use cohort studies?

Although much progress has been made in understanding the pathophysiology of RA, very few data are present on the cause of the disease. During the last years genetic factors (HLA, the X -chromosome) and environmental factors (smoking) have been identified as factors that are more often present in RA patients than in controls. By using a cohort study that enrols all patients with arthritis of less than two years of disease duration (The Leiden Early Arthritis Clinic), we were able to identify additional risk factors to develop RA such as a reduced fecundity in RA patients. However the current methodology to identify risk factors can be questioned. This presentation will focus on the alternative techniques such as case-case series or case-control studies as a more efficient approach to identify risk factors to develop RA.