Epidemiology of restless legs syndrome.

Historically, epidemiological studies of restless legs syndrome (RLS) have been limited by the subjective nature of the disease, the lack of standardized diagnostic criteria, and the sometimes indolent onset of the condition. Ekbom initially estimated a 5% prevalence of RLS in the general population [1]. Subsequent general population surveys by Strang [2] and Cirignotta [3] demonstrated prevalences of 2.5% (Australia) and 1.2% (Italy), respectively. However, one questionnaire survey of United States veterans reported a 29% prevalence of ‘restless or crawling sensations at night’ [4]. A large population-based survey involving 2,019 people in Canada reported that 15% of responders reported delayed sleep-onset due to ‘restlessness in [their] legs’, while 10% reported ‘unpleasant leg sensations’ associated with awakenings from sleep [5]. Although these two screening questions are likely very sensitive for RLS, their specificity is unknown. Since the publication and widespread acceptance of the International Restless Legs Syndrome Study Group (IRLSSG) diagnostic criteria in 1995, epidemiological studies have greatly improved [6]. Rothdach et al. conducted a door-to-door personal interview of 369 people over the age of 65 in Augsburg, Germany [7]. Employing IRLSSG criteria, 13.9% of women and 6.1% of men reported RLS (9.8% total). Patients with RLS also reported a higher prevalence of depression and had lower selfreported mental health scores compared to normal controls. Phillips et al. surveyed 1803 people older than 18 years of age in rural Kentucky by phone [8] and employed a single question (“Do you have unpleasant feelings in your legs – for example, creepy-crawling or tingling feelings – when you lie down at night that make you feel restless and keep you from getting a good night’s sleep?”) to determine the epidemiology of RLS as part of a general health survey. An answer of ‘often’ or ‘very often’ was given by 9.4% of respondents. An affirmative response correlated with other health issues including older age, obesity, poor subjective health, little exercise, diabetes, smoking, and alcohol abstinence. Ulfberg et al. conducted two separate studies of RLS prevalence in Sweden [9]. A written questionnaire, including IRLSSG criteria for RLS, was sent to 4000 men aged 18–64 years. RLS was found in 5.8%, and was correlated with greater age. RLS patients also reported more headaches, depressed mood, and decreased libido. A similar questionnaire was sent to 200 women aged 18–64 years [10]. RLS was reported in 11.4% and was correlated with headache and daytime somnolence. RLS patients tend to present to physicians in mid to later life, but many report subtle symptoms dating from their second or third decades [11,12]. Presentation in adolescence or even infancy is not rare [13]. It has been suggested that pediatric patients with RLS report different phenotypes that do not meet IRLSSG criteria, but rather resemble attentiondeficit/hyperactivity disorder (ADHD) [14]. Therefore, true pediatric epidemiology is not known. RLS can occur in all ethnic backgrounds; however, most feel that Caucasians are most affected. While most Caucasian surveys demonstrate an approximate 10% prevalence, two surveys in Asian populations report much lower prevalences. Tan et al., in a door-to-door survey of 1000 people over age 21 in Singapore, found only one person (0.1%) who met IRLSSG criteria for RLS [15]. Kageyama et al. distributed a written questionnaire asking “if you ever experience sleep disturbances due to creeping sensations or hot feeling in your legs” to 3600 women and 1012 men [16]. They reported that approximately 5% responded affirmatively to that single question. It is likely, however, that strict adherence to IRLSSG criteria would reduce that figure. There are no epidemiological reports of RLS in people of African descent. Anecdotally, African-Americans only rarely present with RLS, but it is unclear whether this Sleep Medicine 3 (2002) S13–S15