Published online August 1, 2007
PEDIATRICS Vol. 120 No. 2 August 2007, pp. 253-266 (doi:10.1542/peds.2006-2767)
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ARTICLE

Restless Legs Syndrome: Prevalence and Impact in Children and Adolescents—The Peds REST Study

Daniel Picchietti, MDa, Richard P. Allen, PhDb, Arthur S. Walters, MDc, Julie E. Davidson, MPHd, Andrew Myers, PhDe and Luigi Ferini-Strambi, MDf

a University of Illinois and Carle Clinic Association, Urbana, Illinois
b Department of Neurology, Johns Hopkins University, Baltimore, Maryland
c Seton Hall University School of Graduate Medical Education and New Jersey Neuroscience Institute at JFK Medical Center, Edison, New Jersey
d Worldwide Epidemiology, GlaxoSmithKline R&D, Harlow, United Kingdom
e Premark Services, Crawley Down, United Kingdom
f Sleep Disorders Center, Università Vita-Salute and IRCCS H San Raffaele, Milan, Italy


   ABSTRACT
TOP
 ABSTRACT
METHODS
 RESULTS
 DISCUSSION
 CONCLUSIONS
 REFERENCES
 
OBJECTIVES. Restless legs syndrome, a common neurologic sleep disorder, occurs in 5% to 10% of adults in the United States and Western Europe. Although ~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 10523 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 ≥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.

Key Words: restless legs syndrome • prevalence • sleep disorder • growing pains • attention-deficit/hyperactivity disorder • depression • anxiety • children • adolescents

Abbreviations: RLS—restless legs syndrome • NIH—National Institutes of Health • ADHD—attention-deficit/hyperactivity disorder

Restless legs syndrome (RLS) is a common neurologic sleep disorder in adults characterized by the following diagnostic criteria: an urge to move that is usually associated with unpleasant sensations, and symptoms that are worse at rest, relieved by movement, and most severe at night.1,2 Population-based studies in adults using these 4 essential diagnostic criteria for RLS found a prevalence of 5% to 10% in the United States and Western Europe.3–9 In 2 studies, the prevalence of moderately to severely affected adults, with 2 to 3 days per week or more of symptoms and a significant impact on the quality of life, was ~2.5%.3,10 Less extensive studies have found lower prevalence in Asian populations11–13 and in India.14,15 The impact of RLS can be quite severe, with significant adverse effects in adults on sleep,16 cognitive function,17,18 mood,19 and quality of life.3,20 Nonetheless, the condition continues to be significantly underdiagnosed.10,21

Although Ekbom22,23 reported RLS symptomatology in childhood as early as the 1940s, it was not until the mid-1990s that detailed pediatric case reports with polysomnography appeared in the literature.24,25 Other case reports and case series have followed.26–35 Consensus criteria for the diagnosis of RLS in children and adolescents were published in 2003 after a workshop at the National Institutes of Health (NIH)2 and are summarized in Fig 1. The pediatric criteria evolved out of the adults RLS criteria and 2 previous versions of pediatric criteria.25,36 Two major concepts were incorporated, more difficult to achieve criteria than in adults for a definitive diagnosis in children and separate research categories for less definitive cases. The first was agreed on to avoid overdiagnosis in children and the second to try and capture a broader spectrum of RLS in childhood for research purposes. On the basis of clinical experience and the development of better language skills in adolescents than in young children, the NIH committee decided to use the adult criteria for adolescents, although the categories of probable and possible RLS were left open as an option for research. These new pediatric RLS criteria were subsequently included in the International Classification of Sleep Disorders Diagnostic Manual (second edition).37 Work on pediatric RLS in the past 12 years has emphasized the familial occurrence of RLS, the association with periodic limb movements in sleep, and the relationship to attention-deficit/hyperactivity disorder (ADHD) in some cases.38


Figure 1
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  		FIGURE 1 NIH Workshop diagnostic criteria for RLS in children (2003). PLMS indicates periodic limb movements in sleep.

 
Studies have indicated that many adults with RLS retrospectively recall that their symptoms started in childhood or adolescence. Two such reports noted onset of RLS for 25% in the 10- to 20-year-old age range.39,40 A pediatric RLS prevalence of 5.9% was found at the Mayo Clinic pediatric sleep disorders clinic,27 and another study found a prevalence of 1.3% in 12 pediatric practices.41 In addition, a study that included a question about "leg restlessness at bedtime" found this in 6.1% of Canadian children 11 to 13 years old.42 However, no published studies have used the essential adult criteria or the pediatric consensus criteria to assess the prevalence of RLS in children and adolescents in the general population.

The aims of the Peds RLS Epidemiology, Symptoms, and Treatment (Peds REST) study were to characterize the epidemiology of pediatric RLS in 2 general populations, in the United Kingdom and United States, as well as collect data on symptoms, severity, family history, impact, diagnosis rates, treatments, and comorbidities.


   METHODS
TOP
 ABSTRACT
 METHODS
RESULTS
 DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Study Population
A random selection of households identified from a large, volunteer market-research panel in the United Kingdom and United States were invited to participate in this survey. Respondents were blinded to the content of the survey before accepting the invitation, and only 1 survey was permitted per household. Those enrolled into the survey were households with ≥1 child in the eligible age range (8–17 years inclusive), where the eligible child was the biological child of the responding adult and where informed consent was given. When >1 child was eligible in a household, the survey child was selected randomly by using the last-birthday method.43 Figure 2 depicts the selection and enrollment process.


Figure 2
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  		FIGURE 2 Entry of participants into the study.

 
The volunteer market-research panel consisted of ~163000 respondents in the United Kingdom and 128000 in the United States. Members were originally enrolled into the panel through an online invitation and agreed to participate in surveys on a variety of topics such as leisure, consumer products, and health. Respondents were paid a sum equivalent to approximately $12 or 10 Euros for completing each survey.

Survey Design
The survey consisted of questions about RLS symptoms, the impact of symptoms on sleep and daytime function, treatment-seeking behavior, diagnoses, treatments received, comorbidities, and family history of RLS (Table 1). The survey consisted of 4 sections with the last 2 sections containing detailed questions for those who responded positively to earlier questions indicative of RLS. We stratified by age into 2 groups: 8 through 11 years, inclusive, and 12 through 17 years, inclusive. This follows US Food and Drug Administration age groupings, which are slightly different from NIH age groupings that have a break point at 13 years rather than 12 years. In the complete survey, there were 48 total questions about the 8- to 11-year-olds and 49 about the 12- to 17-year-olds. The surveys were field tested by 6 families, each with a child or adolescent patient known to have RLS by expert evaluation. Half were in the younger age group and half in the older group. The surveys were found to perform well in this sample. Where the eligible child was age 8 to 11 years old, the responding parent was asked to complete the survey with the child present for the section that contained questions about leg sensations. Where the eligible child was age 12 to 17, the sections referring to symptoms experienced, distress, and consequences were completed by the adolescent. The survey was administered online and respondents were routed automatically to relevant questions on the basis of their responses. The research was conducted from April 11 to 25, 2005.


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  		TABLE 1 Questionnaire Summary

 
RLS Case Definition
On the basis of the pediatric NIH criteria2 (Fig 1), a survey response-based algorithm for definite and probable RLS, appropriate to each of the 2 age groups, was developed by an expert panel (Drs Picchietti, Allen, Walters, and Ferini-Strambi). Case status was evaluated sequentially, with respondents being assessed first for definite RLS and then for probable RLS. Where verbatim descriptors were used in the RLS definitions, the descriptors were reviewed by 3 experts (Drs Picchietti, Allen, and Walters) in a blinded fashion. The focus of this article is definite RLS. Although extensive data for probable RLS were collected, probable RLS was only included in the prevalence analysis, and there as a separate table. Additional work is planned to assess the role of probable RLS in the pediatric diagnostic scheme. Moderate-to-severe RLS was defined as RLS with symptom frequency of at least twice per week and at least moderate distress reported (on a 4-point scale: extremely, moderately, a little, or not at all).

There were specific survey questions to exclude simple positional discomfort, leg cramps, arthralgias, and sore muscles from being counted as RLS.

Analysis
Analysis was conducted by using the Statistical Package for the Social Sciences software (SPSS, Inc, Chicago, IL). When appropriate, differences between groups were tested by using descriptive tests (eg, {chi}2 test statistic, Student's t statistic) and confidence intervals.


   RESULTS
TOP
 ABSTRACT
 METHODS
 RESULTS
DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Survey Population
Entry of participants into the study is depicted in Fig 2. Of 266686 households invited to participate, 38548 responded in the time frame needed to obtain an adequate sample size. Of those, 12874 families had a child in the valid age range, 11815 consented to participate, and 11582 were eligible on the basis of the requirement that a biological parent complete the survey. A total of 10523 completed the detailed survey. Thus, 4% of the total pool was sampled, and of those meeting all eligibility screens, 91% completed the survey. Of the 10523 children and adolescents, there were 2133 girls and 2192 boys in the 8- to 11-year age range, and in the 12- to 17-year age range there were 2981 girls and 3217 boys.

Of 4325 participants in the 8- to 11-year age range, 2092 were from the United Kingdom and 2233 from the United States. Of 6198 participants in the 12- to 17-year age range, 2707 were from the United Kingdom and 3491 from the United States. Because prevalence rates were not significantly different between the United Kingdom and the United States, data were combined in each age range for analysis, except for comorbidity data, which did show significantly different rates of comorbid diagnoses between countries.

Prevalence of RLS Symptoms
A total of 206 children and adolescents met the diagnostic criteria for definite RLS (Table 2). This corresponds with a prevalence of 1.9% for ages 8 to 11 years and 2.0% for ages 12 to 17 years. Of these, 27% (22 of 81) and 52% (65 of 125), respectively, reported moderate-to-severe RLS, corresponding with prevalence estimates of 0.5% and 1.0%. Criteria for "probable 1" RLS were met by an additional 0.7% of 8- to 11-year-olds and 0.3% of 12- to 17-years-olds (Table 3).


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  		TABLE 2 Prevalence of Definite RLS: Ages 8 to 17 Years

 

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  		TABLE 3 Prevalence of Probable RLS: Age 8 to 17 Years

 
No significant gender differences were found in either age group for definite or probable RLS. See Table 4 for a detailed analysis of gender data for the definite RLS groups.


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  		TABLE 4 Definite RLS: Gender Analysis

 
Parents of children 8 to 11 years reported the "age at which uncomfortable feelings in the legs first appeared" in their child as: <5 years old for 15%, 5 to 7 years old for 63%, and ≥8 years old for 22%.

Symptoms Reported and Perceived Impact of RLS
Descriptions of RLS
For the children 8 to 11 years old, detailed descriptions of the RLS feelings were obtained because in this age range urge and a description in the child's own words, consistent with leg discomfort are required for the "definite 1" category (Fig 1). Examples of the descriptions provided by participants are in Table 5.


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  		TABLE 5 Descriptions of Sensory Complaints: Age 8 to 11 Years

 
Growing Pains
Children and adolescents with definite RLS were significantly more likely to report experience of "growing pains" compared with those who did not meet the criteria for definite or probable RLS (overall 80.6% vs 63.2%; P < .001). Table 6 lists percent with a history of growing pains by age category.


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  		TABLE 6 History of Growing Pains

 
Distress
When asked how distressing the RLS symptoms were (extremely, moderately, a little, or not at all), 22.2% (18 of 81) of responding parents of the 81 children who met definite RLS criteria reported that the symptoms were extremely distressing to their children, 32.1% (26 of 81) reported moderate distress, 39.5% (32 of 81) reported a little distress, and 6.2% (5 of 81) stated the symptoms were not at all distressing. Adolescents meeting definite RLS criteria (n = 125) were asked directly about their level of distress, and 23.2% (29 of 125) reported extreme distress, 40.8% (51 of 125) moderate distress, 31.2% (39 of 125) a little distress, and 4.8% (6 of 125) no distress.

Respondents were asked to select from a list the RLS symptoms that they experienced. See Fig 3A for the proportions of respondents reporting each symptom. In response to a question about which symptoms were most troublesome, adolescents with RLS reported inability to get comfortable (32.0%) and inability to stay still/urge to move (29.6%), whereas parents of children with RLS reported inability to get comfortable (30.9%) and pain (22.2%) to be the most bothersome to their child. Figure 3B provides symptom rates for children and adolescents with moderate-to-severe RLS, which were typically higher than all with RLS. For most symptoms there were not significant differences between children and adolescents (Fig 3).


Figure 3
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  		FIGURE 3 A, Symptoms reported: children and adolescents with definite RLS. B, Symptoms reported: children and adolescents with moderate-to-severe RLS. a Significant difference 8 to 11 vs 12 to 17 years at the P < .05 level.

 
Sleep Disturbance
Children and adolescents with definite RLS were significantly more likely to have a history of difficulty falling asleep or staying asleep at night, compared with those who did not meet the criteria for definite or probable RLS (overall: 69.4% vs 39.6%; P < .001). Table 7 lists the percentage with difficulty falling asleep or staying asleep by age category. Adolescents with definite RLS reported sleeping for a mean of 7.1 (median: 7) hours on a school night. Hours of reported sleep was not available for the 8- to 11-year-olds. Parents of 8- to 11-year-olds with definite RLS reported a mean of 2.1 (median: 2) nights of disturbed sleep per week for their children, whereas adolescents with definite RLS reported disturbed sleep with a mean frequency of 3.2 (median: 3) nights per week. This figure for adolescents is significantly higher on average (t = 4.0529; df = 204; P < .001) than it is for the children. A total of 83.9% of parents of children with definite RLS reported that their child, when suffering from RLS symptoms, took >30 minutes to fall asleep and would wake up on average 1.9 (SD: 1.5) times per night. A total of 77.6% of adolescents with definite RLS reported taking >30 minutes on average to get to sleep when suffering from RLS symptoms and would wake a mean of 2.5 (SD: 1.8) times a night.


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  		TABLE 7 Difficulty Falling Asleep or Staying Asleep at Night

 
Daytime sleepiness was reported in 21.0% of 8- to 11-year-olds and 33.6% of 12- to 17-year-olds with definite RLS.

Perceived Consequences
Respondents were asked to select from a list of potential correlates that they thought were related to their leg discomfort (Fig 4A). For children with definite RLS, the most commonly reported consequence of RLS symptoms listed by parents was a negative influence on the child's mood (53.1%), followed by an inability to sit still in the afternoon or evening (46.9%), and next a lack of energy (29.6%). The most frequent effect of RLS symptoms listed by adolescents with RLS was an inability to sit still in the late afternoon or evening (60.8%), followed by a negative influence on mood (47.2%), a lack of energy (40.8%), and an inability to concentrate on schoolwork/work (40.0%). For those with moderate-to-severe RLS, many of the reported consequences were more prevalent, including a negative influence on mood and a lack of energy (Fig 4B). For most perceived consequences, there were not significant differences between children and adolescents (Fig 4).


Figure 4
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  		FIGURE 4 A, Perceived consequences: children and adolescents with definite RLS. B, Perceived consequences: children and adolescents with moderate-to-severe RLS. a Significant difference 8 to 11 vs 12 to 17 years at the P < .001 level; b significant difference 8 to 11 vs 12 to 17 years at the P < .05 level.

 
RLS Diagnoses, Treatment, Family History, and Comorbid Conditions
RLS Diagnoses
Consulting patterns for all children and adolescents with definite RLS were investigated. Of the 81 children with definite RLS, 38 (46.9%) were reported to have had ≥1 medical consultation for RLS symptoms in the 12 months before the survey and of 125 adolescents with definite RLS, 64 (51.2%) reported a consultation. In response to the question "What diagnosis, if any, has your child been given for these symptoms?" the most common medical explanation reported as given for the RLS symptoms was the same for both children (16 of 38 consulting) and adolescents with definite RLS (29 of 64 consulting), namely that the symptoms were part of normal development (44.1%). The percentage of those whose medical consultation for RLS symptoms produced a diagnosis of RLS was 23.7% (9 of 38) for children with definite RLS and 21.9% (14 of 64) for adolescents with definite RLS. The overall rates of a medical diagnosis of RLS for all of those with definite RLS was, therefore, 11.1% (9 of 81) of children and 11.2% (14 of 125) of adolescents.

Of the 22 children meeting the criteria for moderate-to-severe RLS, 11 (50.0%) parents reported medical consultation about the child's symptoms in the last 12 months, and of these, 3 (27.3%) reported that the child received a diagnosis of RLS. Correspondingly, the parents of 41 of 65 adolescents (63.1%) with moderate-to-severe RLS reported that health care had been sought for the RLS symptoms in the last 12 months, with 10 (24.4%) of 41 reporting a subsequent RLS diagnosis. Thus, overall rates of medical diagnosis of RLS in the moderate-to-severe groups were: 13.6% (3 of 22) for children and 15.4% (10 of 65) for adolescents.

Treatment
Ongoing treatment with prescription medication for children and adolescents with definite RLS was reported low, but similar: 6.2% (5 of 81) and 6.4% (8 of 125), respectively. However, in only 3 cases total (1.5%) were the medications listed those that might be considered appropriate in the adult RLS literature44,45: ropinirole (n = 1) and codeine (n = 2). Others listed for RLS treatment were amitriptyline, celecoxib, methylphenidate, amphetamine/dextroamphetamine, atomoxetine, coproxamol, and a topical antiinflammatory agent. Clonidine and clonazepam were not mentioned.

Family History of RLS
A family history of RLS was common in the "definite 1" RLS group for children (n = 70) and the "definite RLS" group for adolescents (n = 125). The "definite 2" RLS group for children (n = 11) was not included for this analysis because the presence of a first-degree relative with RLS is part of entry criteria for this group (Fig 1). At least 1 parent responding positively to the RLS question was found in 71.4% (50 of 70) of the definite 1 RLS children and in 80.0% (100 of 125) of the definite RLS adolescents. Both parents responding positively to the RLS question was found in 17.1% (12 of 70) and 16.0% (20 of 125) of families, respectively. Gender analysis of parental RLS found 44 mothers and 18 fathers positive for RLS of "definite 1" RLS 8- to 11-year-olds, and 83 mothers and 37 fathers of definite RLS 12- to 17-year-olds, resulting in parental female to male ratios of 2.4:1 and 2.2:1, respectively.

We compared children and adolescents meeting the diagnostic criteria for RLS and having a positive family history of RLS to those meeting the diagnostic criteria but having no family history RLS. There were no significant differences for sleep disturbance (question 3) or for any of the perceived consequences listed in Fig 4A (P > .05).

Comorbidity
A question on medical history was included in the survey, and respondents were asked to select from a list which, if any, diagnoses had been received. The list consisted of diagnoses that might potentially confound, mimic, or interact with RLS (Table 8). As expected, a medical diagnosis of growing pains (29.6% of children and 36.8% of adolescents with RLS) was the most common diagnosis reported. These data on a medical diagnosis of growing pains should not be confused with the data in Table 6, which refer to a history of growing pains in response to the question "Do they, or have they, experienced ‘growing pains’?" answered by the parent. Other common medical diagnoses were attention-deficit disorders (14.8% and 17.6%, respectively), depression (3.7% and 14.4%, respectively), and anxiety disorders (4.9% and 8.0%, respectively). Children or adolescents with RLS in the United States were more likely to have received a diagnosis for an attention-deficit disorder, depression, or an anxiety disorder than children or adolescents with RLS in the United Kingdom.


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  		TABLE 8 Self-Reported Medical Diagnoses: Children and Adolescents With Definite RLS

 

   DISCUSSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
CONCLUSIONS
 REFERENCES
 
To our knowledge, this is the first large-scale, population-based study of RLS prevalence and impact in children and adolescents and is the first to use specific pediatric RLS definitions in a general population survey. The most important finding in this study was the high prevalence of definite RLS, 1.9% of children 8 to 11 years old and 2.0% of adolescents 12 to 17 years old. In addition, about one quarter of the children and one half of the adolescents with definite RLS met criteria for moderate-to-severe RLS. The approximate 2% prevalence in 8- to 17-year-olds exceeds that of nonfebrile seizure disorders (~0.5%) and diabetes type 1 and 2 combined (<1%) in this same age range, and is similar to estimates of pediatric obstructive sleep apnea (~2%).37,46 This RLS prevalence is consistent with 7 large epidemiologic studies in adults, which have found a 5% to 10% prevalence in the United States and Western Europe,3–9 when adjusted for the fact that 25% of adult RLS patients reported in 2 different studies onset of RLS between 10 to 20 years old.39,40 This would give a predicted prevalence of ~1.25% to 2.5%, surprisingly close to the results from this survey. The only other pediatric population-based study related to RLS that we are aware of is a longitudinal study of French-Canadian children that included a question about "leg restlessness at bedtime" and found 6.1% of 1353 children ages 11 to 13 years to consistently have this complaint.42 Adding in the other RLS diagnostic criteria would be expected to reduce this number appreciably. Also, it should be noted that the French-Canadian population has one of the highest reported general-population RLS prevalence rates, estimated at 15% to 20%.47,48

We found the prevalence of RLS in boys and adolescent males similar to girls and adolescent females, which is in sharp contrast to adult RLS studies that have consistently reported a 2:1 female to male ratio.4 Although our survey emphasized current symptoms, parents reported recall of onset of RLS in the 8 to 11-year-olds at <5 years of age in 15% and 5 to 7 years old in 63%, indicating that children younger than those included in our study may be affected by RLS.

The descriptions of RLS feelings reported by the 8- to 11-year-olds (Table 5) provided convincing data to us that this survey did successfully measure restless legs symptomatology. Themes of bug-like sensations, ticklish feelings, electricity, jumpiness, and "energy" were common and are consistent with our extensive clinical experience diagnosing RLS in children and adolescents. A history consistent with RLS was reported by more than two thirds of parents of the definite RLS children and adolescents, supporting this aspect as helpful in the diagnostic criteria for RLS in children and adolescents.49 Of note, there were a remarkable number of families in which both parents reported RLS symptoms (~1 of 6 families). This extra "genetic load" may play a role in the age of onset and severity of RLS in childhood. The increased prevalence of RLS symptoms in mothers compared with fathers is consistent with adult prevalence studies, which have shown an approximate 2:1 ratio of females to males.4 Parity is considered a major factor in explaining this gender difference.4

It is likely that primary and secondary RLS cases are included in our data. Although Table 8 lists 17 medical diagnoses that we asked about, we did not include a question about all active medical conditions, we did not ask about all current medications, and this large survey did not include screening laboratory tests. Known causes of secondary RLS include renal failure, pregnancy, peripheral neuropathy, and some medications.50,51 Nonetheless, it is probable that the majority of our cases are primary RLS given the relatively low occurrence of these factors in the age range studied and the predominance of primary RLS in cases with onset before age 45.52 We did find self-reported medical diagnoses of anemia or iron deficiency, which are known aggravating factors for RLS, in 2.5% children 8- to 11-year- olds and 4.8% 12- to 17-year-olds.

Growing Pains
Beginning with Ekbom's work on RLS in the 1940s to 1970s, there has been controversy over the relationship of growing pains to childhood RLS.23,35,53 We believe our data shed some light on this issue. A history of growing pains was common in 8- to 17-year-olds with RLS (over three quarters), but it was also common in those without RLS (almost two thirds). Although statistically significant and useful for group data, this difference is not likely to be a key factor in the decision as to whether an individual patient has RLS. However, we have found growing pains to be a clinically useful "lead-in" question to a more specific discussion of RLS symptoms. Perhaps more relevant is the disparately high medical diagnosis rate of growing pains in children with RLS compared with a low medical diagnosis of RLS (Table 8), suggesting that the much more specific diagnosis of RLS was missed and that an opportunity for treatment was also missed.

Impact
The impact of RLS in children and adolescents seems to be substantial. The frequency and severity of RLS feelings were reported as moderate-to-severe in about one quarter of the 8- to 11-year-olds and about half of the 12- to 17-year-olds (at least twice per week and moderately or extremely distressing). Sleep disturbance was very commonly reported in the children and adolescents meeting criteria for definite RLS, exceeding two thirds, and much more than in those without RLS (Table 7). Perceived consequences of RLS were common, with difficulty sitting in the late afternoon or evening, a negative effect on mood, a lack of energy, and an inability to concentrate frequently reported in the definite RLS groups, and even more pronounced in the moderate-to-severe RLS groups (Fig 4). Given the emerging literature on the effect of sleep disturbance on cognitive and affective function in children and adolescents, these aspects are of notable concern.54–60 It has been our experience that in more severe cases of pediatric RLS, treatment can be of benefit. However, it should be noted that there are currently no US Food and Drug Administration–approved treatments for RLS in children and adolescents.

Diagnosis and Treatment
Our data indicate that RLS is uncommonly diagnosed in children and adolescents, even for those who reported that they sought medical care for the symptoms. Less than 1 in 4 who sought medical care received an RLS diagnosis, with diagnosis rates only marginally better for those moderately to severely affected. Most often a medical explanation of normal development was reported. Because RLS is not generally recognized as a medically significant disorder, there may be a tendency to discount these symptoms as unimportant or interpret them as an expression of more familiar medical conditions. In cases where medication was prescribed, only 1 of the medications reported would be considered first-line treatment for RLS in the adult literature.1,45

Because this was a survey and not a clinical evaluation, it is possible that other diagnoses could explain the symptoms of the children and adolescents who met definite RLS criteria in our study. However, the extensive inclusion and exclusion criteria used in this study, as well as rigorous application of NIH criteria, make this unlikely in our opinion. It should be noted that the NIH definite RLS criteria in those <12 years old requires more symptoms than are required for a diagnosis in adults. This was devised to avoid overdiagnosis in children. More likely, the low medical diagnosis rates of RLS reflect a lack of awareness among those providing medical care for children and adolescents. In 2 major US pediatric textbooks RLS is mentioned sparingly, a total of 2 paragraphs.46,61 Low awareness of RLS has been documented for those who provide health care for adults, although there is evidence that awareness is improving.3,21,62

Comorbidity
Comorbidity of definite RLS with medically diagnosed ADHD, depression, and anxiety disorders in our study is of interest. These all were found at rates higher than diagnosis rates reported in the general pediatric population,63,64 but caution regarding these findings is warranted given the small sample size in some of the cells. In addition, there were much lower diagnosis rates in the United Kingdom than in the United States, perhaps reflecting lower occurrence but more likely because of higher diagnosis and treatment rates of some behavioral conditions in the United States than in the United Kingdom and Europe.65,66 There is considered to be a complex relationship between ADHD and sleep disorders in children, and a substantial literature exists.38,58,67,68 In adults with RLS, there are increased rates of depression,19 anxiety,69,70 and ADHD71 compared with the general population. Although various theories exist, there is some evidence that RLS and these conditions have a negative interactive effect with each other, and that their association may reflect some shared common pathology.19,67

Limitations
Methodologic issues should be considered in the interpretation of our results. First, the ascertainment of RLS status was by self-report via the parents or adolescents, not by clinical interview. Although it is possible that other conditions could have been reported as RLS symptomatology, a detailed set of questions to exclude known mimics of RLS was part of the survey. It is reassuring that there were low rates of diabetes, arthritis, and sciatic problems in the RLS cases found, because these are known confounders of the diagnosis in adults. Also, in the clinical setting the diagnosis of RLS is based on history, not requiring physical examination for a positive diagnosis. Second, our survey was conducted in a convenience sample of Internet users. United Kingdom census data suggest that 55% of households in the United Kingdom had Internet access in July 2005.72 US census data from October 2003 provided by the US Department of Commerce indicated that ~55% of households in the United States had Internet access and that access was strongly associated with income.73 However, by spring 2004 the Internet usage rate was measured at 63% for adults in the United States, and the income gap was closing.74 To the extent that the prevalence of RLS, parent observation of symptoms, and health care utilization are associated with factors influencing Internet use or propensity to volunteer in research surveys, our results, like those from all similar population studies, may be biased. Third, the 10523 participating households represents a 4% subset of the initially invited households, which itself is a subset of the total United Kingdom and US households. To limit enrollment bias we did not disclose the specific survey topic until all eligibility criteria were met and enrollment was terminated after the 2 weeks it took to obtain an adequate sample size. Fourth, although the NIH pediatric RLS diagnostic criteria are a consensus of expert opinion, these criteria have not been validated extensively in the clinical setting. Fifth, in families where there was a parent with RLS, it is possible that those parents would have been more likely to identify the symptoms in their children influencing the prevalence rates in familial cases. Having the adolescents complete the RLS questions directly and having the younger children present when the parent completed the questions about sensory symptoms should have reduced this type of bias.


   CONCLUSIONS
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 CONCLUSIONS
REFERENCES
 
This large, population-based study found restless legs to be quite prevalent in children and adolescents aged 8 to 17 years. Many of these children and adolescents had moderately to severely distressing symptoms and reported that RLS adversely affected both sleep and daytime function. Medical diagnosis rates of RLS were low, and treatment was uncommon.


   ACKNOWLEDGMENTS
 
We thank Trevor Brown of Premark, Inc, for assistance in organizing this project.


   FOOTNOTES
 
Accepted Apr 3, 2007.

Address correspondence to Daniel Picchietti, MD, University of Illinois School of Medicine and Carle Clinic Association, Department of Pediatrics, 602 W University Ave, Urbana, IL 61801. E-mail: dpicchie{at}uiuc.edu

This study was presented at the SLEEP 2006 meeting; June 17–22, 2006; Salt Lake City, UT.

Financial Disclosure: This project was supported by GlaxoSmithKline Research and Development. Dr Picchietti receives grant support from the Carle Foundation.


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