What can epidemiology tell us about systemic lupus erythematosus?

Systemic lupus erythematosus (SLE) is an often-severe autoimmune rheumatic disease most commonly diagnosed in women in their childbearing years. It is thought to develop when genetically predisposed individuals are exposed to one or more environmental triggers. This review outlines the epidemiologic evidence for several putative risk factors including cigarette smoke, hormonal and reproductive factors, environmental silica and infectious exposures, as well as many yet to be identified. We also review the evidence for factors associated with increased disease activity and adverse outcomes in SLE. We review the literature on the epidemiology of SLE, its distribution, potential risk factors for its onset and for adverse outcomes. The information considered in this review was gathered through extensive review of the literature. Online Pubmed literature searches, previous reviews of the epidemiology of SLE and original studies were employed. Epidemiologic studies have helped to identify some of these potential risk factors, including exogenous hormone use, cigarette smoking, infections such as Epstein-Barr virus (EBV) and crystalline silica exposure, but many more have yet to be studied. These exposures may interact with multiple genetic factors in determining susceptibility to SLE. While epidemiologic research has contributed an enormous amount to our understanding of the disease and its pathogenesis, there are many more avenues of epidemiologic research that deserve to be pursued.