Update on the epidemiology of systemic lupus erythematosus: new spins on old ideas.

Systemic lupus erythematosus is a serious autoimmune disease of obscure etiology with a propensity for widespread organ involvement. Its manifestations range from ephemeral symptoms to life-threatening events such as thromboses and strokes. Although once considered rare, SLE now appears to be relatively common in certain subsets of the population. Considerable publicity for this disorder as a "silent killer" has heightened public awareness and may have contributed to the increases in the number of individuals reporting this diagnosis in surveys. Epidemiologic studies face numerous challenges in disease classification and case ascertainment. Despite this, such studies have increased in size and number, and have generated novel etiologic hypotheses, ranging from environmental pollutants to viral infections.