Prevalence of restless legs syndrome in non-institutionalized Japanese elderly.

The purpose of the present paper was to evaluate the prevalence of restless legs syndrome (RLS) in a non-institutionalized Japanese elderly population. The subjects consisted of 8900 elderly people >65 years of age belonging to the Seniors Association in Izumo City in November 2000. The present study was conducted in two parts. The phase 1 investigation was a screening by mailed questionnaire and the phase 2 investigation was diagnosis by face-to-face interview. Subjects with possible cases of RLS in phase 1 proceeded to phase 2 and definite cases of RLS were then detected. In phase 1, a total of 3287 subjects completely answering all questionnaire items, were defined as the subjects of the present study. A total of 150 were classified as having 'probable RLS', resulting in a prevalence of 4.6%. These subjects with probable RLS in phase 1 were detected as the subjects of phase 2. By face-to-face interview and various clinical examinations, a total of 35 subjects (nine male, 26 female) were diagnosed as having definite RLS, resulting in a prevalence of 1.06%. Furthermore, seven subjects (two male, five female) with symptomatic RLS were detected and finally 28 subjects (seven male, 21 female) were diagnosed as having idiopathic RLS. It was significantly higher in women for both the total and idiopathic RLS groups (0.60% male vs 1.46% female; 0.46% male vs. 1.18% female, respectively). The prevalence of RLS may be lower in the Japanese elderly than that in Caucasian subjects. These results could enhance understanding of the differences in predisposition between the races.