RLS epidemiology--frequencies, risk factors and methods in population studies.

Since the introduction of the four minimal criteria for restless legs syndrome (RLS) in 1995 by the International Restless Legs Syndrome Study Group, the number of published studies in RLS during the past 10 years has substantially increased. These studies improved our knowledge about prevalences, risk factors or outcomes of the disease at the population level and provided hypothesis about potential biological mechanism. This article reviews the existing studies on the prevalence and risk factors of RLS and critically describes existing methodological problems in the assessment of the disease in epidemiologic studies.