Restless legs syndrome: diagnostic criteria, special considerations, and epidemiology. A report from the restless legs syndrome diagnosis and epidemiology workshop at the National Institutes of Health

BACKGROUND

Restless legs syndrome is a common yet frequently undiagnosed sensorimotor disorder. In 1995, the International Restless Legs Syndrome Study Group developed standardized criteria for the diagnosis of restless legs syndrome. Since that time, additional scientific scrutiny and clinical experience have led to a better understanding of the condition. Modification of the criteria is now necessary to better reflect that increased body of knowledge, as well as to clarify slight confusion with the wording of the original criteria.

SETTING

The restless legs syndrome diagnostic criteria and epidemiology workshop at the National Institutes of Health.

PARTICIPANTS

Members of the International Restless Legs Syndrome Study Group and authorities on epidemiology and the design of questionnaires and scales.

OBJECTIVE

To modify the current criteria for the diagnosis of restless legs syndrome, to develop new criteria for the diagnosis of restless legs syndrome in the cognitively impaired elderly and in children, to create standardized criteria for the identification of augmentation, and to establish consistent questions for use in epidemiology studies.

RESULTS

The essential diagnostic criteria for restless legs syndrome were developed and approved by workshop participants and the executive committee of the International Restless Legs Syndrome Study Group. Criteria were also developed and approved for the additional aforementioned groups.

Restless Legs Syndrome Prevalence and Impact

BACKGROUND

Restless legs syndrome (RLS), a common sensorimotor disorder, has a wide range of severity from merely annoying to affecting sleep and quality of life severely enough to warrant medical treatment. Previous epidemiological studies, however, have failed to determine the prevalence of those with clinically significant RLS symptoms and to examine the life effects and medical experiences of this group.

METHODS

A total of 16 202 adults (aged >/=18 years) were interviewed using validated diagnostic questions to determine the presence, frequency, and severity of RLS symptoms; respondents reporting RLS symptoms were asked about medical diagnoses and the impact of the disorder and completed the Short Form-36 Health Survey (SF-36). Criteria determined by RLS experts for medically significant RLS (frequency at least twice a week, distress at least moderate) defined "RLS sufferers" as a group most likely to warrant medical treatment.

RESULTS

In all, 15 391 fully completed questionnaires were obtained; in the past year, RLS symptoms of any frequency were reported by 1114 (7.2%). Symptoms occurred at least weekly for 773 respondents (5.0%); they occurred at least 2 times per week and were reported as moderately or severely distressing by 416 (2.7%). Of those 416 (termed RLS sufferers), 337 (81.0%) reported discussing their symptoms with a primary care physician, and only 21 (6.2%) were given a diagnosis of RLS. The SF-36 scores for RLS sufferers were significantly below population norms, matching those of patients with other chronic medical conditions.

CONCLUSION

Clinically significant RLS is common (prevalence, 2.7%), is underdiagnosed, and significantly affects sleep and quality of life.

The prevalence of symptoms in end-stage renal disease: a systematic review

Symptoms in end-stage renal disease (ESRD) are underrecognized. Prevalence studies have focused on single symptoms rather than on the whole range of symptoms experienced. This systematic review aimed to describe prevalence of all symptoms, to better understand total symptom burden. Extensive database, "gray literature," and hand searches were undertaken, by predefined protocol, for studies reporting symptom prevalence in ESRD populations on dialysis, discontinuing dialysis, or without dialysis. Prevalence data were extracted, study quality assessed by use of established criteria, and studies contrasted/combined to show weighted mean prevalence and range. Fifty-nine studies in dialysis patients, one in patients discontinuing dialysis, and none in patients without dialysis met the inclusion criteria. For the following symptoms, weighted mean prevalence (and range) were fatigue/tiredness 71% (12% to 97%), pruritus 55% (10% to 77%), constipation 53% (8% to 57%), anorexia 49% (25% to 61%), pain 47% (8% to 82%), sleep disturbance 44% (20% to 83%), anxiety 38% (12% to 52%), dyspnea 35% (11% to 55%), nausea 33% (15% to 48%), restless legs 30% (8%to 52%), and depression 27% (5%to 58%). Prevalence variations related to differences in symptom definition, period of prevalence, and level of severity reported. ESRD patients on dialysis experience multiple symptoms, with pain, fatigue, pruritus, and constipation in more than 1 in 2 patients. In patients discontinuing dialysis, evidence is more limited, but it suggests they too have significant symptom burden. No evidence is available on symptom prevalence in ESRD patients managed conservatively (without dialysis). The need for greater recognition of and research into symptom prevalence and causes, and interventions to alleviate them, is urgent.

Sleep-disordered breathing in community-dwelling elderly

These are the final results of a survey of sleep-disordered breathing, which examined objective and subjective information from a large randomly selected elderly sample. We randomly selected 427 elderly people aged 65 yr and over in the city of San Diego, California. Twenty-four percent had an apnea index, AI, greater than or equal to 5 and 62% had a respiratory disturbance index, RDI, greater than or equal to 10. Correlates of sleep-disordered breathing included high relative weight and reports of snoring, breathing cessation at night, nocturnal wandering or confusion, daytime sleepiness and depression. Body mass index, falling asleep at inappropriate times, male gender, no alcohol within 2 hr of bedtime and napping were the best predictors of sleep-disordered breathing. Despite statistical significance, all of the associations between interview variables and apnea indices were small. No combination of demographic variables and symptoms allowed highly reliable prediction of AI or RDI.

Epidemiology of restless legs symptoms in adults

BACKGROUND

Restless legs syndrome (RLS) is a disorder characterized by sleep-disrupting unpleasant leg sensations, often accompanied by daytime behavioral problems. Treatment for this condition is available, but it is suspected that most instances of RLS remain undiagnosed. The goal of this investigation was to assess the prevalence and health status correlates of restless legs symptoms (hereinafter referred to as restless legs) in the general population.

METHODS

A question reflecting the clinical features of RLS was added to the 1996 Kentucky Behavioral Risk Factor Surveillance Survey. Data on the frequency of experiencing restless legs, self-rated general and mental health status, demographics, and behavioral risk factors were collected by telephone interview from 1803 men and women, 18 years and older.

RESULTS

Experiencing restless legs 5 or more nights per month was reported by 3% of participants aged 18 to 29 years, 10% of those aged 30 to 79 years, and 19% of those 80 years and older. The age-adjusted prevalence for Kentucky adults is 10.0%; prevalence did not vary significantly by sex. The adjusted odds ratios (95% confidence intervals) for restless legs and diminished general health and poor mental health status were 2.4 (1.4-4.0) and 3.1 (2.0-4.6), respectively. Restless legs were significantly associated with increased age and body mass index, lower income, smoking, lack of exercise, low alcohol consumption, and diabetes.

CONCLUSIONS

The prevalence of restless legs in the general adult population is high. Restless legs may be associated with decreased well-being, emphasizing the need for further research and greater medical recognition of this condition.

Sex and the Risk of Restless Legs Syndrome in the General Population

BACKGROUND

Restless legs syndrome (RLS) is characterized by the desire to move the limbs associated with paresthesias of the legs, a motor restlessness, an intensification of symptoms at rest with relief by activity, and a worsening of symptoms in the evening or at night. Population-based studies are rare, and risk factors in the general population are not known.

METHODS

Cross-sectional survey with face-to-face interviews and physical examination among 4310 participants in the Study of Health in Pomerania in northeastern Germany. Participants were aged 20 to 79 years and were randomly selected from population registers. Restless legs syndrome was assessed with standardized, validated questions addressing the 4 minimal criteria for RLS as defined by the International Restless Legs Syndrome Study Group.

RESULTS

The overall prevalence of RLS was 10.6%, increasing with age, and women were twice as often affected as men. While nulliparous women had prevalences similar to those among men up to age 64 years, the risk of RLS increased gradually for women with 1 child (odds ratio, 1.98; 95% confidence interval, 1.25-3.13), 2 children (odds ratio, 3.04; 95% confidence interval, 2.11-4.40), and 3 or more children (odds ratio, 3.57; 95% confidence interval, 2.30-5.55). Subjects with RLS had significantly lower quality-of-life scores than those without the syndrome.

CONCLUSIONS

Restless legs syndrome is a common disease in the general population, affecting women more often than men. It is associated with reduced quality of life in cross-sectional analysis. Parity is a major factor in explaining the sex difference and may guide further clarification of the etiology of the disease.

Sleep disturbance in cancer patients

Sleep difficulty is a prominent concern of cancer patients, yet there has been no large study of the prevalence and nature of sleep disturbance in cancer patients. This cross-sectional survey study examined: (a) the prevalence of reported sleep problems in patients attending six clinics at a regional cancer centre; (b) sleep problem prevalence in relation to cancer treatment; and (c) the nature of reported insomnia (type, duration, and associated factors). For three months, all patients attending clinics for breast, gastrointestinal, genitourinary, gynecologic, lung, and non-melanoma skin cancers were offered a brief sleep questionnaire. Response rate was 87%; the final sample size was 982. Mean age of respondents was 64.9 years (SD 12.5). The most prevalent problems were excessive fatigue (44% of patients), leg restlessness (41%). insomnia (31%), and excessive sleepiness (28%). Chi square tests showed significant variation among clinics in the prevalence of most sleep problems. The lung clinic had the highest or second-highest prevalence of problems. The breast clinic had a high prevalence of insomnia and fatigue. Recent cancer treatment was associated with excessive fatigue and hypersomnolence. Insomnia commonly involved multiple awakenings (76% of cases) and duration > or = 6 months (75% of cases). In 48% of cases, insomnia onset was reported to occur around the time of cancer diagnosis (falling within the period 6 months pre-diagnosis to 18 months post-diagnosis). The most frequently identified contributors to insomnia were thoughts, concerns, and pain/discomfort. In a multivariate logistic regression analysis, variables associated with increased odds of insomnia were fatigue, age (inverse relationship), leg restlessness, sedative/hypnotic use, low or variable mood, dreams, concerns, and recent cancer surgery. This study provides new information about sleep-related phenomena in cancer patients, information which will be useful in planning supportive care services for cancer patients.

Prevalence of restless legs syndrome and periodic limb movement disorder in the general population

BACKGROUND

Periodic limb movement disorder (PLMD) and restless legs syndrome (RLS) are two sleep disorders characterized by abnormal leg movements and are responsible for deterioration in sleep quality. However, the prevalence of these disorders is not well known in the general population. This study aims to document the prevalence of RLS and PLMD in the general population and to identify factors associated with these conditions.

METHODS

Cross-sectional studies were performed in the UK, Germany, Italy, Portugal and Spain. Overall, 18,980 subjects aged 15 to 100 years old representative of the general population of these five European countries underwent telephone interviews with the Sleep-EVAL system. A section of the questionnaire assessed leg symptoms during sleep. The diagnoses of PLMD and RLS were based on the minimal criteria provided by the International Classification of Sleep Disorders.

RESULTS

The prevalence of PLMD was 3.9% and RLS was 5.5%. RLS and PLMD were higher in women than in men. The prevalence of RLS significantly increased with age. In multivariate models, being a woman, the presence of musculoskeletal disease, heart disease, obstructive sleep apnea syndrome, cataplexy, doing physical activities close to bedtime and the presence of a mental disorder were significantly associated with both disorders. Factors specific to PLMD were: being a shift or night worker, snoring, daily coffee intake, use of hypnotics and stress. Factors solely associated with RLS were: advanced age, obesity, hypertension, loud snoring, drinking at least three alcoholic beverages per day, smoking more than 20 cigarettes per day and use of SSRI.

CONCLUSIONS

PLMD and RLS are prevalent in the general population. Both conditions are associated with several physical and mental disorders and may negatively impact sleep. Greater recognition of these sleep disorders is needed.

Prevalence and risk factors of RLS in an elderly population: the MEMO study. Memory and Morbidity in Augsburg Elderly

OBJECTIVE

To evaluate prevalence, sociodemographic characteristics, and risk factors of restless legs syndrome (RLS) in a population-based survey of the elderly, using standard diagnostic criteria.

BACKGROUND

Population-based studies of RLS are rare and have not yet used standard definition criteria.

METHODS

The Memory and Morbidity in Augsburg Elderly (MEMO) Study is a follow-up project of the World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease (MONICA) Survey-Augsburg, Germany, 1989-1990, evaluating neurologic diseases and their risk factors in a German population 65 to 83 years of age. Two RLS-trained physicians assessed the prevalence of RLS based on the four minimal standard criteria (International Restless Legs Syndrome Study Group, 1995) using standardized questions in face-to-face interviews. They also obtained information on medical history, medications, depression (Center of Epidemiologic Studies Depression Scale), and quality of life (Short Form 36) and performed a standardized neurologic examination for each participant.

RESULTS

The study population included 369 participants (173 women and 196 men). The overall prevalence of RLS was 9.8% (n = 36) and higher in women (13.9% versus 6.1%; p = 0.02). In women, the prevalence did not change with age, whereas men showed a nonsignificant inverse trend with increasing age. RLS-positive individuals took more benzodiazepines and estrogen compared with non-RLS cases, but the differences were not statistically significant. Participants with RLS had higher incidence of depression (p = 0.012) and lower self-reported mental health scores (p = 0.029) than did non-RLS cases.

CONCLUSIONS

RLS is a frequent syndrome in the elderly with considerable impact on self-perceived mental health, affecting women about twice as often as men.

Impact, diagnosis and treatment of restless legs syndrome (RLS) in a primary care population: the REST (RLS epidemiology, symptoms, and treatment) primary care study

OBJECTIVES

To assess the frequency, impact, and medical response to the restless legs syndrome (RLS) in a large multi-national primary care population.

METHOD

Questionnaire surveys of matched patients and primary care physicians (PCPs) in five modern industrialized western countries.

RESULTS

An RLS screening questionnaire was completed by 23,052 patients: 2223 (9.6%) reported weekly RLS symptoms; 1557 of these patients had medical follow-up questionnaires completed both by themselves and by their physician. An RLS sufferer subgroup (n=551) likely warranting treatment was defined as reporting at least twice weekly symptoms with appreciable negative impact on quality of life. A total of 88.4% of RLS sufferers reported at least one sleep-related symptom. Most reported impaired sleep consistent with a diagnosis of insomnia. Out of 551 sufferers, 357 (64.8%) reported consulting a physician about their RLS symptoms, but only 46 of these 357 (12.9%) reported having been given a diagnosis. PCPs reported that 209 (37.9%) RLS sufferers consulted them about RLS symptoms, but only 52 (24.9%) were given an RLS diagnosis. In most countries, sufferers, regardless of diagnosis, were prescribed therapies not known to be effective in RLS.

CONCLUSIONS

RLS significantly impairs patients' lives, often by severely disrupting sleep. The marked under-diagnosis and inappropriate treatment of RLS indicates that PCPs need better education about this condition. Recognizing how often disrupted sleep results from RLS should improve diagnosis.

Prevalence of restless legs syndrome among men aged 18 to 64 years: an association with somatic disease and neuropsychiatric symptoms

Standardized diagnostic criteria determined by the International Restless Legs Syndrome Study Group were used to investigate the current prevalence of restless legs syndrome (RLS). Possible associations between RLS and neuropsychiatric and somatic complaints were also investigated. A random sample of 4,000 men living in central Sweden were sent a questionnaire that included questions about sleep habits, symptoms of sleepiness, and somatic and neuropsychiatric complaints. Four symptom questions accepted as minimal diagnostic criteria for RLS were also included. Odds (OR) ratios and 95% confidence interval (CI) for different variables were calculated by means of multivariate logistic regression; 5.8% of the men suffered from RLS. The prevalence of RLS increased with age. Sleep-related complaints were more frequent among the RLS sufferers. Complaints of headache at awakening and daytime headache were reported three to five times more frequently among RLS sufferers and there was a tendency toward reported social isolation related to RLS. Subjects with RLS more frequently reported depressed mood (OR, 2.6; 95% CI, 1.8-3.8), and complained more often of reduced libido (OR, 2.2; 95% CI, 1.4-3.3). RLS sufferers more frequently reported hypertension (OR, 1.5; 95% CI, 0.9-2.4) and heart problems (OR, 2.5; 95% CI, 1.4-4.3). Results show that restless legs syndrome is common among men. It is hypothesized that RLS may be associated with several somatic and neuropsychiatric symptoms.

Restless legs syndrome: A community-based study of prevalence, severity, and risk factors

OBJECTIVE

To assess the prevalence and severity of restless legs syndrome (RLS) in the general community and to investigate its potential relationship with iron metabolism and other potential risk factors.

METHODS

This was a cross-sectional study of a sex- and age-stratified random sample of the general population (50 to 89 years; n = 701). The diagnosis of RLS was established by face-to-face interviews; severity was graded on the RLS severity scale. Each subject underwent a thorough clinical examination and extensive laboratory testing.

RESULTS

The prevalence of RLS was 10.6% (14.2% in women, 6.6% in men); 33.8% of all patients with RLS had mild, 44.6% had moderate, and 21.6% had severe disease expression. None had been previously diagnosed or was on dopaminergic therapy. Free serum iron, transferrin, and ferritin concentrations were similar in subjects with and without RLS. However, soluble transferrin receptor (sTR) concentrations were different in subjects with and without RLS (1.48 vs 1.34 mg/L; p < 0.001). Female sex and high sTR independently predicted the risk of RLS.

CONCLUSION

This large survey confirms the high prevalence, female preponderance, and underrecognition of restless legs syndrome in the general community. Although two-thirds of patients had moderate to severe disease, none was on current dopaminergic therapy.

A questionnaire study of 138 patients with restless legs syndrome: the 'Night-Walkers' survey

After verifying the diagnosis of restless legs syndrome (RLS) in 105 patients who are part of a nationwide support group, we undertook a telephone survey of their symptomatology. We then compared the answers with those of 33 of our own RLS patients who had undergone a neurologic examination and had a periodic limb movement in sleep (PLMS) index of > 5 (number per hours of sleep). Although RLS has generally been considered to be a condition of middle to older age, the results for the support group, and for our patients, are similar in that more than a third of the patients in each group experienced their first symptoms before the age of 10. Initial lack of diagnosis or misdiagnosis by a physician were common and the symptoms were commonly thought to be psychogenic whatever the age of onset. In some cases, young age-onset RLS was severe from the start. For younger age-onset patients whose symptoms were severe enough to seek immediate medical attention, confounding or misdiagnosis included "growing pains" and attention deficit hyperactivity disorder. However, medical attention was generally not sought until the fourth decade. Most respondents stated that this was because their symptoms were mild at onset and then progressed. In the older age-onset patients, misdiagnoses also included skin irritation, arthritis, and malingering. A total remission of symptoms of a month or more was present in at least 15% of the individuals in all groups surveyed. More than 50% of the respondents know of one or more first-degree relatives affected by RLS. Five of our 33 patients had RLS initially triggered either by diabetic peripheral neuropathy or lumbosacral radiculopathy.

Restless legs syndrome: prevalence and impact in children and adolescents--the Peds REST study

OBJECTIVES

Restless legs syndrome, a common neurologic sleep disorder, occurs in 5% to 10% of adults in the United States and Western Europe. Although approximately 25% of adults with restless legs syndrome report onset of symptoms between the ages of 10 and 20 years, there is very little literature looking directly at the prevalence in children and adolescents. In this first population-based study to use specific pediatric diagnostic criteria, we examined the prevalence and impact of restless legs syndrome in 2 age groups: 8 to 11 and 12 to 17 years.

METHODS

Initially blinded to survey topic, families were recruited from a large, volunteer research panel in the United Kingdom and United States. Administration was via the Internet, and results were stratified by age and gender. National Institutes of Health pediatric restless legs syndrome diagnostic criteria (2003) were used, and questions were specifically constructed to exclude positional discomfort, leg cramps, arthralgias, and sore muscles being counted as restless legs syndrome.

RESULTS

Data were collected from 10,523 families. Criteria for definite restless legs syndrome were met by 1.9% of 8- to 11-year-olds and 2.0% of 12- to 17-year-olds. Moderately or severely distressing restless legs syndrome symptoms were reported to occur > or = 2 times per week in 0.5% and 1.0% of children, respectively. Convincing descriptions of restless legs syndrome symptoms were provided. No significant gender differences were found. At least 1 biological parent reported having restless legs syndrome symptoms in > 70% of the families, with both parents affected in 16% of the families. Sleep disturbance was significantly more common in children and adolescents with restless legs syndrome than in controls (69.4% vs 39.6%), as was a history of "growing pains" (80.6% vs 63.2%). Various consequences were attributed to restless legs syndrome, including 49.5% endorsing a "negative effect on mood." Data were also collected on comorbid conditions and restless legs diagnosis rates.

CONCLUSIONS

These population-based data suggest that restless legs syndrome is prevalent and troublesome in children and adolescents, occurring more commonly than epilepsy or diabetes.

Sleep and aging: 1. Sleep disorders commonly found in older people

Aging is associated with several well-described changes in patterns of sleep. Typically, there is a phase advance in the normal circadian sleep cycle: older people tend to go to sleep earlier in the evening but also to wake earlier. They may also wake more frequently during the night and experience fragmented sleep. The prevalence of many sleep disorders increases with age. Insomnia, whether primary or secondary to coexistant illness or medication use, is very common among elderly people. Rapid eye movement (REM) sleep behaviour disorder and narcolepsy, although less common, are frequently not considered for this population. Periodic leg-movement disorder, a frequent cause of interrupted sleep, can be easily diagnosed with electromyography during nocturnal polysomnography. Restless legs syndrome, however, is diagnosed clinically. Snoring is a common sleep-related respiratory disorder; so is obstructive sleep apnea, which is increasingly seen among older people and is significantly associated with cardio-and cerebrovascular disease as well as cognitive impairment.

Restless legs syndrome and sleep disturbance during pregnancy: the role of folate and iron

Restless legs syndrome (RLS) is a neurosensory disorder that typically begins in the evening and often prevents a person from falling asleep. It has been associated with iron deficiency anemia and dopaminergic pathways and is often treated with iron infusion or dopamine agonists. The purpose of this secondary analysis of longitudinal data collected on women before, during, and after pregnancy is to document the prevalence of RLS during pregnancy, contrast its effect on sleep and mood state, and explore the role of folate and iron in the expression of RLS, specifically during the third trimester when the syndrome is most distressing. The prevalence increased from 0 during preconception to 23% (n = 7) during the third trimester of pregnancy. Only 1 subject continued to experience RLS after delivery. Compared with those without complaints of restless legs, those with restless legs had low serum ferritin at preconception and significantly lower folate levels during preconception and at each trimester. In addition, time to sleep onset was significantly delayed and depressed mood was significantly higher in the RLS group. Rather than indicators of iron deficiency anemia (serum ferritin, serum iron, and hemoglobin) or pernicious anemia (vitamin B(12)), it was reduced serum folate level that was associated with RLS in this sample of pregnant women. Findings indicate a need to reconsider recommendations about the normal ranges of serum ferritin and serum folate levels during pregnancy to minimize the complaints of restless legs and promote more consolidated sleep and better daytime mood state during pregnancy.

Epidemiology of restless legs syndrome in French adults: A nationwide survey: The INSTANT Study

OBJECTIVE

To evaluate the prevalence, characteristics, and treatment of restless legs syndrome (RLS) in France.

METHODS

In this population-based survey, face-to-face home interviews were conducted among a random sample of 10,263 French adults. A French translation of the four features defined by the International RLS Study Group in 1995 was used to assess the prevalence of symptoms consistent with a diagnosis of RLS. Data on severity of symptoms and their management were also collected.

RESULTS

The 12-month prevalence of RLS symptoms in the French adult population was estimated to be 8.5% (95% CI 8.0%, 9.0%), with a higher prevalence (p < 0.001) observed in women (10.8%) than in men (5.8%). Prevalence increases with age until 64 years and decreases thereafter in both sexes. Half of the identified subjects reported symptoms once a week at least. Symptoms were more severe in subjects reporting symptoms once a week at least compared to subjects with less frequent symptoms. In this group, half of the subjects reported a family history, the age at onset was earlier, and severity of symptoms higher. RLS had been previously diagnosed in only 5.3% of the subjects who reported previous medical diagnosis, and recommended RLS drug treatment was received by 3.4% of the 28.7% currently treated subjects.

CONCLUSIONS

Restless legs syndrome (RLS) occurred in 10% of women and 5% of men. RLS prevalence decreases after the age of 64. RLS is often underdiagnosed and few subjects receive recommended RLS drug treatment.

Restless legs syndrome and pregnancy

OBJECTIVE

To perform a large and detailed epidemiologic study on restless legs syndrome (RLS) during pregnancy and the puerperium.

METHODS

A structured clinical interview, assessing symptoms since the beginning of pregnancy, was performed to a population of 642 pregnant women at the time of delivery and at follow-up evaluation (1, 3, and 6 months after delivery). Main hematologic tests were also evaluated. A woman was considered affected if she met the International RLS Study Group criteria for RLS diagnosis.

RESULTS

Twenty-six percent of women were affected by RLS during their pregnancy. The disease was strongly related to the third trimester of pregnancy and tended to disappear reaching the time of delivery. Affected women presented lower values of hemoglobin and mean corpuscular volume compared with healthy subjects (both groups received the same supplemental iron and folate therapy).

CONCLUSIONS

Pregnancy is associated with transient restless legs syndrome.

Periodic limb movements in sleep in community-dwelling elderly

The prevalence of periodic limb movements in sleep (PLMS) in a randomly selected elderly sample is reported. In San Diego, 427 elderly volunteers aged 65 yr and over were recorded in their homes. Forty-five percent had a myoclonus index, MI greater than or equal to 5. Correlates of PLMS included dissatisfaction with sleep, sleeping alone and reported kicking at night. Although statistically significant, the strengths of the associations between interview variables and myoclonus indices were all small. No combination of demographic variables and symptoms allowed highly reliable prediction of PLMS.

Restless legs syndrome and attention-deficit/hyperactivity disorder: a review of the literature

STUDY OBJECTIVE

To review evidence on the association between restless legs syndrome (RLS) and attention-deficit/hyperactivity disorder (ADHD), to discuss the hypothetical mechanisms underlying this association, and to consider the potential interest for common pharmacologic treatments of RLS and ADHD when co-occurring.

METHOD

A PubMed search.

RESULTS

In clinical samples, up to 44% of subjects with ADHD have been found to have RLS or RLS symptoms, and up to 26% of subjects with RLS have been found to have ADHD or ADHD symptoms. Several mechanisms may explain this association. Sleep disruption associated with RLS might lead to inattentiveness, moodiness, and paradoxical overactivity. Diurnal manifestations of RLS, such as restlessness and inattention, might mimic ADHD symptoms. Alternatively, RLS might be comorbid with idiopathic ADHD. Subjects with RLS and a subset of subjects with ADHD might share a common dopamine dysfunction. Limited evidence suggests that some dopaminergic agents, such as levodopa/carbidopa, pergolide, and ropinirole, may be effective in children with RLS associated with ADHD symptoms.

CONCLUSIONS

Although still limited, evidence from clinical studies demonstrates an association between RLS and ADHD or ADHD symptoms. Further clinical studies using standard criteria and procedures are needed to better estimate the degree of association. Epidemiologic studies are required to assess the relationship between ADHD and RLS symptoms in nonclinical samples. Further investigations should address the mechanisms underlying the relationship between RLS and ADHD. Several dopaminergic agents seem to be promising treatment for RLS associated with ADHD symptoms. To date, however, the absence of randomized and blinded controlled studies does not allow evidence-based recommendations.

CSF iron, ferritin and transferrin levels in restless legs syndrome

The aim of this study is evaluating iron, ferritin, and transferrin in both serum and CSF in patients of restless legs syndrome (RLS), based on the hypothesis that iron deficiency in the central nervous system (CNS) causes the symptoms as a result of the dysfunction of dopaminergic systems. These parameters, polysomnographic sleep measures, and subjective evaluation of the sleep quality were compared in 10 patients of idiopathic RLS (RLS group) and 10 age-matched patients of psychophysiological insomnia without RLS symptoms (non-RLS group). With sleep patterns, sleep latency was longer and sleep efficiency was lower in the RLS group than those in the non-RLS group. Periodic leg movement index in the RLS group was higher than that of the non-RLS group. With serum examination, there were no significant differences for the iron, ferritin, and transferrin values between the both groups. With CSF examination, the iron and ferritin values were lower and the transferrin values were higher in the RLS group than those in the non-RLS group. There was positive correlation between the serum and CSF ferritin levels in the both groups, but the slope of the regression lines for the RLS group was lower than that for the non-RLS group. These results indicate low brain iron concentration caused by the dysfunction of iron transportation from serum to CNS in patients with idiopathic RLS.

Prevalence and correlates of restless legs syndrome symptoms in the Wisconsin Sleep Cohort

BACKGROUND AND PURPOSE

The aim of this study was to estimate the prevalence of restless legs syndrome (RLS) symptoms in the US adult population and to relate frequency of RLS symptoms to self-reported general health, depressive and anxiety symptoms, daytime sleepiness, and cardiovascular disease.

PATIENTS AND METHODS

Data were obtained from a survey, conducted in 2002, of 2821 participants in the Wisconsin Sleep Cohort, a prospective community-based epidemiology study. Classification of RLS symptoms was based on the following four symptoms at the 2002 survey: 'repeated urge to move your legs' and 'strange and uncomfortable feelings in the legs', 'when sitting or lying down' which occur at least weekly, 'get better when you get up and start walking' and 'disrupt your sleep'.

RESULTS

Prevalence of RLS symptoms occurring at least weekly was 10.6%, with no statistical difference between males (9.9%) and females (11.2%). Individuals with symptoms of RLS occurring at least weekly were older than those without such symptoms (P<0.02). Those with Daily RLS symptoms had statistically more frequent excessive daytime sleepiness, poorer self-reported general health, an elevation in depressive and anxiety symptoms, and an increased prevalence of cardiovascular disease compared to those with no RLS symptoms. All of these associations were stronger in subjects with Daily RLS symptoms than those with RLS symptoms 1-6 times per week.

CONCLUSIONS

RLS symptoms are associated with multiple physical and psychological indices of impaired health. Longitudinal studies are required to determine whether RLS symptoms are causally related to excessive daytime sleepiness, poor general health, elevated depression and anxiety symptoms, and cardiovascular disease.

Prevalence and impact of sleep disorders and sleep habits in the United States

PURPOSE

Epidemiologic studies on sleep disorders in the USA have mostly focused on specific disorders in specific groups of individuals. Most studies on sleep habits and sleep-related difficulties have focused on children and adolescents. The authors describe the prevalence of the three common physician-diagnosed sleep disorders (insomnia, sleep apnea, and restless legs syndrome (RLS)) by age, gender, and race in the US population. In addition, the authors describe the sleep habits and sleep-related difficulties in carrying routine daily activities. The authors also investigate the impact of the sleep disorders on performing routine daily activities.

METHODS

Data from the 2005-2006 National Health and Nutrition Examination Survey for 6,139 individuals over the age of 16 was analyzed for sleep-related parameters.

RESULTS

The prevalence was highest for sleep apnea (4.2%), followed by insomnia (1.2%) and RLS (0.4%). Hispanics and Whites reported longer sleep duration than Blacks by 24 to 30 min. The predominant sleep habits were snoring while sleeping (48%), feeling unrested during the day (26.5%), and not getting enough sleep (26%). Difficulty concentrating (25%) or remembering (18%) were the main sleep-related difficulties in our sample. Insomnia, sleep apnea, and RLS had the highest impact on concentration and memory.

CONCLUSIONS

Our findings suggest that the prevalence of sleep disorders in the USA is much lower than previously reported in the literature suggesting under diagnosis of sleep disorders by primary care physicians.

Restless legs syndrome in an Asian population: A study in Singapore

In face-to-face interviews, we examined 157 consecutive individuals aged 55 years and older, selected from the general population in Singapore, and 1,000 consecutive individuals aged 21 years and older, from a primary healthcare center. Based on the IRLSSG criteria, the prevalence of restless leg syndrome (RLS) was 0.6% and 0.1%, respectively.

Restless Legs Syndrome Symptoms in Primary Care

BACKGROUND

There are relatively few studies on the prevalence of restless legs syndrome (RLS) in the general population, even fewer that used diagnostic questions covering all 4 essential diagnostic criteria defining the RLS symptom complex, and none that have reported on the 2 RLS phenotypes for patients seen by family physicians.

METHODS

To determine the prevalence of the symptom complex, diagnostic for RLS in a primary care patient population, a prospective population-based single-center study was performed. Every adult patient presenting for care in a small rural primary care practice with mostly white patients was surveyed for a 1-year period using a validated RLS diagnostic questionnaire.

RESULTS

A total of 2099 patients completed the questionnaire. Analysis revealed that 24.0% of these patients were positive for all 4 of the essential symptoms used to make the diagnosis of RLS and 15.3% reported these symptoms at least weekly. In addition, the RLS symptom complex was reported significantly more often by women than men and, as a whole, patients reporting the RLS symptoms were significantly older than patients without symptoms. The prevalence of symptoms increased with age until about 60 years and then showed a steady decrease thereafter. Further, early-onset RLS was significantly more common in women than men.

CONCLUSIONS

A high prevalence of RLS symptoms was observed in this primary care population. This finding supports the need for heightened awareness in both the medical community and general population regarding this disorder, which can often be effectively treated within the primary care practice.