Epidemiology

Interpreting studies of interactions between RA risk factors

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Interactions between HLA and PTPN22 genotypes and smoking have been implicated in overall susceptibility to rheumatoid arthritis as well as the incidence of particular disease phenotypes in case–control and case-only studies. As recent epidemiological evidence shows, deciphering these interactions demands consideration of the analytical approach used.

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Figure 1: Study designs used to analyze risk factor interactions in RA.

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Correspondence to Elizabeth W. Karlson.

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