ADVERTISEMENT

Issue Navigator

Volume 09 No. 10
Earn CME
Accepted Papers
Classifieds







Scientific Investigations

Restless Legs Syndrome in an Appalachian Primary Care Population: Prevalence, Demographic and Lifestyle Correlates, and Burden

http://dx.doi.org/10.5664/jcsm.3084

Kim E. Innes, M.S.P.H., Ph.D.1,2; Kathryn L. Flack, M.P.H., B.A.1; Terry Kit Selfe, D.C., Ph.D.1,2; Sahiti Kandati, B.D.S.1; Parul Agarwal, M.P.H.3
1Department of Epidemiology, West Virginia University School of Public Health, Morgantown, WV; 2Center for the Study of Complementary and Alternative Therapies, University of Virginia Health System, Charlottesville, VA; 3West Virginia University CoHORTS Center, West Virginia University School of Pharmacy, Morgantown, WV

ABSTRACT

Background:

Restless legs syndrome (RLS) is a common and distressing sensorimotor disorder of unknown etiology. While the epidemiology of RLS has been examined in several North American and European studies, research on RLS and RLS burden in poor, rural populations, including those residing in Appalachia, remains sparse. In this study, we investigated RLS prevalence in an Appalachian primary care population and examined the association of RLS to demographic factors, lifestyle characteristics, sleep quality, and mood disorders.

Methods:

Participants of this anonymous survey study were community-dwelling adults aged ≥ 18 years visiting one of 4 West Virginia primary care clinics. Data gathered included detailed information on sleep patterns, demographic characteristics, lifestyle factors, and health/medical history; the survey also included questions specific to RLS diagnosis and severity. Response rates were excellent, with 68% of eligible adults contacted returning completed surveys (N = 1,424/2,087). Pregnant women (N = 65) and those with missing data on key variables (N = 142) were excluded from the analyses.

Results:

Of the 1,217 participants included in the final analytic sample, 19.6% (18.2% with symptoms at least once/month) met the 4 IRLSSG diagnostic criteria in the absence of positional discomfort or leg cramps; 14.5% reported RLS symptoms at least once/week and 10.1% indicated symptoms ≥ 3×/week. Excluding respondents with diabetes, kidney disease, or anemia reduced these rates only slightly. Those with RLS were more likely to be older, female, lower income, unemployed, disabled, non-Hispanic white, and less likely to be college educated than those without RLS. Mood and sleep impairment were significantly elevated in those with RLS; after adjustment for demographic and lifestyle characteristics, health history, and other factors, those with RLS remained significantly more likely to indicate a history of depression (adjusted odds ratio [OR] = 1.9; 95% confidence interval [CI] = 1.4, 2.6) and anxiety (OR = 1.6, CI 1.1, 2.2), to report sleep impairment both 4 (OR = 2.4, CI 1.6, 3.7) and 7 days/week (OR = 1.8, CI 1.3, 2.4), and a mean sleep duration < 5 h/night (OR = 1.7, CI 1.2, 2.3). These associations increased in both strength and magnitude with increasing symptom frequency (p's for trend ≤ 0.01).

Conclusions:

Findings of this preliminary anonymous survey study suggest that RLS prevalence is high in this Appalachian primary care population and that RLS is associated with significant burden in terms of both mood and sleep impairment.

Citation:

Innes KE; Flack KL; Selfe TK; Kandati S; Agarwal P. Restless legs syndrome in an Appalachian primary care population: prevalence, demographic and lifestyle correlates, and burden. J Clin Sleep Med 2013;9(10):1065-1075.


RLS is a burdensome sleep disorder affecting an estimated average of 15% to 20% of the US general adult population.1,2 Recognition of RLS as an important clinical condition is growing, in part aided by standardized diagnostic criteria developed by international expert consensus in 19953 and revised in 2002.4 RLS is characterized by a compelling urge to move the legs that is usually accompanied by uncomfortable, often painful sensations in the legs, begins or worsens during periods of inactivity, is worse during the evening and nighttime hours, and is partially or totally relieved by movement.4 RLS can have profound negative effects on daily functioning and quality of life (QOL), as well as health care costs and productivity, comparable to those reported in other serious disorders such as Parkinson disease, diabetes, and stroke.59 Primary contributing factors to the significant reductions in QOL with RLS are sleep and mood disturbances. RLS is associated with significant sleep impairment,8,10,11 the most common presenting complaint of patients seeking medical care for RLS.12,13 Likewise, mood disturbance appears common in those affected by RLS,10,14 and can both result from and contribute to sleep deficits.15 RLS has also been linked to increased risk for cardiovascular disease (CVD) and stroke, and has been associated with diabetes and other related chronic conditions.2 However, the etiology of RLS remains poorly understood,1618 and there is still no cure for RLS.

BRIEF SUMMARY

Current Knowledge/Study Rationale: Restless legs syndrome (RLS) is a common and distressing sensorimotor disorder of unknown etiology. While the epidemiology of RLS has been examined in several North American and European studies, research on RLS and RLS burden in poor, rural populations, including those residing in Appalachia, remains sparse.

Study Impact: Findings of this survey study suggest that RLS prevalence is high in this Appalachian primary care population and that RLS is associated with significant burden in terms of both mood and sleep impairment, and may help explain the elevated rates of depression and sleep deficits reported in WV residents. Larger prospective studies are needed to investigate potential causal relationships and to enhance our still incomplete understanding regarding both the etiology and sequelae of RLS in this and other populations.

Prevalence estimates of RLS have varied widely (from 4% to 29%) depending on the study population characteristics, study location, and RLS definition and ascertainment1; even among the five studies in US primary care populations, prevalence estimates have ranged from 13.3%12 to 29.3%.19 Findings have likewise been inconsistent regarding the association of RLS to specific socioeconomic (SES)1,6,2023 and lifestyle characteristics.1,6,2022,24 Moreover, few studies have investigated RLS and RLS burden in poor, rural populations, including those residing in Appalachia. Situated entirely within the Appalachian region, West Virginia is characterized by a rural and socioeconomically disadvantaged population with a health status of citizens among the worst in the country. West Virginia residents rank among the poorest and least educated in the US, and suffer among the highest rates of many chronic health conditions linked to RLS, including arthritis, obesity, and diabetes.2,2527 Recent CDC analyses of 2006 and 2008 data from the Behavioral Risk Factor Surveillance System (BRFSS) also indicate that West Virginia residents suffer the highest prevalence of both depression28 and insufficient rest or sleep29 in the nation. While RLS prevalence in WV adults is likely high and may help explain the elevated rates of both sleep disturbance and depressive disorders in the state, the prevalence and correlates of RLS in WV residents remain unknown. In this anonymous survey study, we investigated RLS prevalence in a sample of WV primary care patients, and examined the association of RLS to demographic factors, lifestyle characteristics, sleep quality, and mood disorders in this population.

METHODS

Study Population and Survey Administration

Participants for this study were ambulatory, community-dwelling, English-speaking adults ≥ 18 years of age visiting 1 of 4 Morgantown area primary care clinics affiliated with the West Virginia University (WVU) Health Sciences Center, and residing in the Morgantown area. Following a brief description of the study, surveys were offered to each patient in the clinic waiting area; eligible participants interested in participating in the study were asked to place the completed survey in an onsite, clearly labeled drop box. Research staff provided assistance to those who wished to participate but were unable to read due to illiteracy or visual impairment. The survey was presented to potential participants as a study regarding sleep patterns in all Morgantown area adults, including both those who slept well and those who did not. Surveys were distributed during 3- to 4-hour time blocks (between the hours of 8 AM and 5:30 PM, Monday-Friday), over the course of 12 weeks; survey administration times and days of the week were rotated systematically in each clinic to ensure similar coverage across clinics and to reduce the probability of selection bias based on timing of survey administration. The survey instrument included 41 self-report items and required 5-10 minutes to complete. Survey responses were anonymous, and no personally identifying information was collected. Data gathered included detailed information on: sleep duration and quality during the past 7 days; demographic characteristics; lifestyle; current height and weight; history of physician diagnosed chronic health conditions, including depression and anxiety; current medications for these conditions; and, in women, reproductive history. This anonymous survey study was approved by the West Virginia University Institutional Review Board.

As illustrated in Figure 1, a total of 2,392 patients were approached regarding participation in the study. Of these, 305 were ineligible to participate (due to age under 18, residence out of the catchment area, inability to understand English, or other factors). Of the remaining 2,087 adults contacted, 1,538 patients indicated interest in participating and accepted the survey. Of these 1,538 surveys distributed, 1,424 completed surveys were collected from the drop boxes, yielding an overall survey response rate of 68%. Representation was approximately equal among the 4 clinics (N = 352, 353, 355, and 364), although response rates varied slightly from 66% to 77%. Women were more likely to respond than men (76.7% vs. 65.4%, respectively, p = 0.0004). Pregnant women (N = 65) were excluded from the analytic sample, leaving a total of 1,359 eligible adults. Exclusion of those with any missing data on RLS symptoms (N = 27, 2.0%) and on demographics, lifestyle characteristics, sleep profiles, and other covariates of interest (N = 115, 8.1%), yielded a final analytic sample of 1,217 primary care patients. Those with missing data were more likely to be older (52.2 ± 0.5 vs. 47.2 ± 2.0 years, p = 0.005) and retired (33% vs. 18%, p = 0.02), and were less likely to be college graduates (18% vs. 34%, p = 0.001), be physically active (38 vs. 52%, p = 0.02), and report an annual income over $25,000 (50% vs. 72%, p < 0.001) than those without missing data. Relative to those included in the analysis, participants with incomplete data did not differ in other demographic or lifestyle characteristics, or in sleep patterns, health profiles, or other factors (p > 0.2).

Study flow diagram

jcsm.9.10.1065a.jpg

jcsm.9.10.1065a.jpg
Figure 1

Study flow diagram

(more ...)

Measurement of Outcomes, Indices of Burden, and Major Covariates

Ascertainment of RLS

The primary outcome of interest, RLS was assessed via responses to 7 survey questions adapted from a previously validated, 7-item self-report diagnostic questionnaire30 and designed to capture the 4 International Restless Legs Syndrome Study Group's (IRLSSG) diagnostic criteria (Figure 2),4 exclude common RLS mimics (leg cramps and positional discomfort), and determine presence of accompanying unpleasant sensations. After a small pilot survey suggesting that certain items in the original validated RLS questionnaire might be confusing to some participants, we adapted the wording of some questions to render them simpler and easier for our target population to understand. To ensure we were indeed capturing the same symptom cluster as the original questionnaire items, we surveyed a sample of 118 non-pregnant adults visiting the 4 target clinics using the original 7 questionnaire items30). This survey produced broadly comparable results in terms of prevalence, correlates, and associated burden as did our revised survey, yielding an overall prevalence rate of 18.1%, with 16.7% of participants reporting symptoms ≥ once/month, and 11.1% reporting symptoms ≥ 3×/ week. However, as suggested by the confusion expressed by some participants in our pilot survey, the rate of missing data was much higher for the RLS items using the original vs. our revised questionnaire (15.3% vs. 1.9%).

Diagnostic criteria for restless legs syndrome

jcsm.9.10.1065b.jpg

jcsm.9.10.1065b.jpg
Figure 2

Diagnostic criteria for restless legs syndrome

(more ...)

The adapted questionnaire included the following questions: (1) “Do you ever have an urge to move your legs that is difficult to resist?” If YES: (2) Will simply changing leg position by itself once without continuing to move usually relieve these feelings?” (3) “Is this urge to move usually accompanied by unpleasant sensations in the legs?” (4) “Are the unpleasant sensations due to leg cramping?” (5) “Does the urge to move or unpleasant sensations begin or worsen during periods of rest or inactivity such as lying or sitting?” (6) “Is the urge to move or the unpleasant sensations partially or totally relieved by movement, such as walking or stretching?”; and (7) “Does the urge to move or the unpleasant sensations only occur or get worse in the evening or night?” RLS symptom frequency was ascertained via an 8th question: “How often do you experience these symptoms?” (Circle one: less than once/month, 1-3 days/month, 1-2 days/week, and 3 or more days/ week). RLS was defined as an affirmative response to all 4 RLS diagnostic questions (#1, 5-7, above) and a negative response to questions 2 and 4. Since the presence of unpleasant sensations is not an essential diagnostic criterion for RLS, but rather an often associated characteristic,4 the prevalence and correlates of RLS with unpleasant sensations were assessed in separate analyses. Participants were also asked, in a separate section of the questionnaire, if they had received a physician diagnosis of RLS and/ or were taking medications for RLS.

Demographic and Lifestyle Characteristics

Demographic characteristics were assessed via self-report survey questions, and included age, gender, race/ ethnicity, education (< 12 years, high school graduate, some college, ≥ 4 years post high school [college graduate]), employment status (employed, unemployed/out of work, homemaker, retired, student, disabled), marital status (single, married or cohabiting, widowed, divorced), annual household income (< $25,000, $25,000-50,000, $50-75,000, > $75,000). Lifestyle factors assessed included caffeine consumption (2 items), smoking history and current status (5 items), and engagement in physical activity (2 items).

Sleep and Mood Disturbance

Five survey items assessed number of days (0-7) during the past week that the participant experienced specific sleep problems (early awakening, difficulty falling asleep, difficulty staying asleep, daytime fatigue/somnolence, and insufficient rest). An additional, open-ended question was used to ascertain sleep duration (in hours and minutes) during the past week. The items were adapted from a series of questions regarding sleep quality and duration introduced to the National Health and Nutrition Examination Survey (NHANES) in the 2005-6 cycle.31 Participants were considered to have a history of a specific mood disorder, including depression and anxiety, if they reported receiving a physician diagnosis of the condition and/or indicated they were currently taking prescription medications for this disorder in response to specific structured queries.

Other Health-Related Factors

BMI was calculated as (weight in kg/height in m2). Obesity was defined as BMI ≥ 30. History of a specific chronic health disorder (anemia, hypertension, high cholesterol, heart disease, stroke, kidney disease, diabetes, osteoarthritis, rheumatoid arthritis, and other conditions) was defined as reported physician diagnosis of, and/or currently taking prescription medications for, this disorder.

Analysis

All data were analyzed using SPPS v. 20. Prevalence estimates for RLS were adjusted for age and sex using WV 2010 census data32 and calculated both overall and by symptom frequency (any frequency, at least once/week, and ≥ 3×/week). Potential differences between participants with and without missing data were evaluated using the Student t-test or Mann-Whitney U Test for continuous or ordinal variables, and χ2 test for categorical variables. We used multiple logistic regression to determine the independent associations of RLS to demographic and lifestyle factors, depression, anxiety, and sleep disturbances, and to assess the influence of potential confounders and effect modifiers; linear trends were assessed using polynomial contrasts. Unless stated otherwise, multivariable models were adjusted for demographic factors and lifestyle characteristics, as well as BMI and comorbid conditions, including anemia, kidney disease, heart conditions, hypertension, and diabetes. All p-values presented are 2-sided.

Sleep duration was assessed as both a dichotomous (< 5 h vs. ≥ 5 h/night) and a continuous variable. Similarly, we analyzed sleep quality as both a dichotomous variable (reported sleep problems 4 and 7 days/week) and a continuous variable (total and mean score of the 5 sleep quality questions). Component questions were analyzed both individually and as a composite score. Scale reliability testing of completed questionnaires indicated adequate internal consistency of the grouped 5 items (Cronbach α = 0.85). To determine the utility of the 5-item scale, we also ran a Principal Components factor analysis, using an eigenvalue cutoff value of 1.5 and factor loading of 0.65. All items loaded strongly on one domain (loading values 0.77-0.83, eigenvalue = 3.2) and explained 63% of the total variance, with the Kaiser–Meyer–Olkin (KMO) measure of sampling adequacy (0.81) and Bartlett test values (p < 0.0001) further supporting use of the composite scale.

RESULTS

Table 1 gives the crude and age- and sex-adjusted prevalence rates for RLS for the entire population, the analytic sample, and a population subset that excludes participants with specific conditions linked to RLS. Of the 1,217 respondents included in this analysis, 19.6% (17.9% adjusted for age and sex) met the 4 IRLSSG diagnostic criteria and/or reported a physician diagnosis of RLS and did not report symptoms due to leg cramps or positional discomfort; of the 238 respondents with RLS, 93% (18.2% of total respondents) indicated symptoms at least once/month (Table 1). Over 70% of those meeting criteria for RLS (14.5% of total respondents) reported symptoms at least once/week, and > 50% (10.1% of total respondents) indicated symptoms ≥ 3×/week. Restricting RLS cases to those whose symptoms were accompanied by unpleasant sensations slightly reduced prevalence estimates (16.8% for any frequency symptoms, 15.6% for symptoms ≥ once/month, 12.4% for symptoms ≥ once/week, 9.0% for symptoms ≥ 3×/ week). Excluding respondents with diabetes, kidney disease, or anemia attenuated the overall prevalence rates only slightly (RLS prevalence rates = 18.1% for any frequency symptoms (17.5% adjusted for age and sex), 16.9% for symptoms ≥ once/ month (17.0% adjusted), 13.2% for symptoms ≥ once/week (13.2% adjusted), and 8.4% for symptoms ≥ 3×/week (8.9% adjusted) (Table 1). Likewise, excluding those on medications for depression or anxiety resulted in only a modest reduction in overall prevalence estimates (17.7% for any frequency symptoms, 16.3% for symptoms ≥ once/month, 12.6% for symptoms ≥ once/week, and 8.6% for symptoms ≥ 3×/week [data not shown]). Thirteen respondents reported a diagnosis of RLS but did not meet current RLS symptom criteria.

Restless legs syndrome (RLS) prevalence* in an adult West Virginia primary care population

jcsm.9.10-1065.t01.jpg

table icon
Table 1

Restless legs syndrome (RLS) prevalence* in an adult West Virginia primary care population

(more ...)

Of the 238 participants in our analytic sample meeting all criteria for RLS, only 66 (28%) had received a physician diagnosis, of whom 31 (13% of those meeting criteria for RLS) were on RLS medications. Interestingly, of the 66 respondents who were diagnosed with RLS, those currently on RLS medications were over 3× more likely than those who were not on medication to report symptoms ≥ 3×/week (OR adjusted for age and sex = 3.1, CI 1.0, 9.7).

Study population characteristics by RLS status are given in Table 2. Participants were predominantly female (64%), non-Hispanic white (92%), over 40 years of age (65%), and married or cohabiting (68%). Fewer than 35% had completed at least 4 years of college, and approximately 50% reported an annual household income of under $50,000. Almost 40% of participants were obese, and > 60% reported at least one comorbid health condition, with 24% reporting ≥ 3 comorbid disorders.

Demographic and lifestyle characteristics of non-pregnant adults ≥ 18 years of age attending 4 primary care clinics, stratified by RLS (N = 1,217)

jcsm.9.10-1065.t02.jpg

table icon
Table 2

Demographic and lifestyle characteristics of non-pregnant adults ≥ 18 years of age attending 4 primary care clinics, stratified by RLS (N = 1,217)

(more ...)

Association of RLS to Demographic, Lifestyle, and Health Characteristics

Participants with RLS were significantly more likely to be older, non-Hispanic white, female, and unemployed or disabled and less likely to be college-educated or to report a family income over $75,000 after adjustment for other demographic, lifestyle, and health-related factors (Table 2). RLS was also significantly and positively related to obesity (OR = 1.5, 95% CI 1.1, 2.0) and to comorbidity, with likelihood of RLS increasing with increasing number of comorbid conditions. Those with RLS also appeared less likely to be from minority populations (OR = 0.6, CI 0.3, 1.0). While RLS was significantly related to sedentary lifestyle and current smoking in the unadjusted analysis (OR for exercise < 1 h/ week = 1.4, CI 1.0, 1.9; OR for current smoking = 1.5, CI 1.0,2.1), adjustment for other factors attenuated these associations (OR's = 1.2 [0.8, 1.6] and 1.3[0.9,1.9], respectively). RLS did not appear related to marital status or to caffeine consumption in this population. Restriction of RLS cases to those reporting symptoms ≥ 1-2×/week slightly strengthened the protective association between RLS and minority status (adjusted OR = 0.30, CI 0.1, 0.8) and college education (adjusted OR = 0.4, 0.2, 0.7), but did not alter the association of other demographic or lifestyle factors to RLS.

Association of RLS to Mood and Sleep Disturbance

RLS was associated with significantly increased sleep and mood disturbance in this population (Table 3). Those with RLS were approximately twice as likely to report a history of depression (OR adjusted for demographic characteristics = 1.9, CI 1.4, 2.6) or anxiety disorders (adjusted OR = 1.6 [1.1, 2.2]) and to be taking medications for these conditions (adjusted ORs = 1.5 [CI 1.1, 2.2] and 1.6 [CI 1.1, 2.3, respectively). Similarly, those meeting criteria for RLS were over twice as likely to report symptoms of sleep disturbance ≥ 4 days/week after adjustment for demographic and other factors, including difficulty falling asleep (OR = 2.1, CI 1.6, 2.9), difficulty staying asleep (OR = 2.3, CI 1.8, 3.2), awakening too early (OR = 2.3, CI 1.7, 3.0), feeling sleepy or tired during the day (OR = 2.4, CI 1.7, 3.5), or receiving insufficient rest (OR = 2.5, CI 1.8, 3.4) (Table 3). Likewise, those with RLS were approximately twice as likely to suffer daily sleep disturbance symptoms (adjusted ORs = 1.7 to 1.9) as those not meeting criteria for RLS (Table 3). Reported sleep duration was strongly and inversely associated with RLS (OR per 30-min increment = 0.8, CI 0.7, 0.9), with participants meeting RLS criteria 70% more likely to report sleeping < 5 h/night (OR = 1.7, CI 1.2, 2.3). Again, of the 66 participants who had received an RLS diagnosis, those who were on RLS medications appeared over twice as likely to indicate a history of depression or anxiety (OR adjusted for age and sex = 2.3, CI = 0.9, 6.0), and were approximately 3× as likely to be currently taking medications for these conditions (adjusted OR = 3.2, CI 1.1, 8.9), and to report insufficient rest daily (adjusted OR = 2.6, CI 1.0, 7.3) relative to those not on RLS medication.

Association of RLS to sleep and mood disturbance in non-pregnant adults ≥ 18 years of age attending 4 WVU primary care clinics

jcsm.9.10-1065.t03.jpg

table icon
Table 3

Association of RLS to sleep and mood disturbance in non-pregnant adults ≥ 18 years of age attending 4 WVU primary care clinics

(more ...)

As illustrated in Table 4, the associations of RLS to sleep and mood disturbance increased progressively in both strength and magnitude with rising symptom frequency. For example, compared to those without RLS, the relative odds of reporting a diagnosis of depression showed a significant, progressive increase from 1.5 (CI 0.85, 2.6) in those reporting symptoms less than once per week to 2.5 (CI 1.7, 3.7) in those with symptoms ≥ 3×/week (p's for trend ≤ 0.0001). Similarly, the likelihood of diagnosed anxiety disorder increased progressively with increasing RLS symptom frequency (OR's for symptoms < 1×/ week, 1-2×/week, and ≥ 3×/week = 1.1 (0.7, 1.9), 2.0 (1.1, 3.6), 2.2 (1.3, 3.1), respectively; p for trend = 0.002) (Table 4). Associations of RLS to current treatment for anxiety and depression showed a similar, strong progressive increase in strength and magnitude with increasing symptom frequency (Table 4).

Association of RLS to sleep and mood disturbance by frequency of RLS symptoms (N = 1,217 adults ≥ 18 years of age attending 1 of 4 WV primary care clinics)

jcsm.9.10-1065.t04.jpg

table icon
Table 4

Association of RLS to sleep and mood disturbance by frequency of RLS symptoms (N = 1,217 adults ≥ 18 years of age attending 1 of 4 WV primary care clinics)

(more ...)

Likewise, the elevated likelihood of sleep disturbance ≥ 4 days a week in those with RLS rose from a modest, nonsignificant 20% in those with symptoms less than once per week (OR = 1.2, CI 0.7, 2.2) to almost 5-fold in those with frequent symptoms (4.6, CI 2.3, 9.3) (p for trend = 0.00007). The relation of RLS to daily sleep disturbance and to reduced sleep duration showed a similar pattern, as did the association of RLS to both composite and individual sleep disturbance scores. Additional adjustment for BMI and comorbidity did not appreciably alter these associations, nor did excluding those with conditions previously linked to RLS, including diabetes, kidney disease, and anemia. Likewise, restricting RLS cases to those with unpleasant leg sensations slightly strengthened, but did not otherwise materially change the associations with sleep impairment (ORs = 2.5 [1.6, 3.8] and 1.9 [1.4, 2.6] for sleep disturbance at least 4 and 7 days/week, respectively), or with depression and anxiety (ORs = 2.2 [1.6, 3.1] and 1.9 [1.3, 2.6], respectively). Similarly, expanding RLS cases to include the 13 respondents who were diagnosed with RLS but did not meet all questionnaire criteria did not appreciably change any of the associations observed.

DISCUSSION

To our knowledge, this is the first study of RLS to target an Appalachian primary care population. In brief, findings of this survey suggest that prevalence of RLS is high among Morgan-town area primary care patients; 19.6% (17.9% adjusted for age and sex) met criteria for RLS, with 14.5% reporting symptoms at least once/week and 10.1% indicating symptoms at least 3×/ week. Excluding respondents with diabetes, kidney disease, or anemia reduced these rates only slightly. Fewer than one-third of those meeting RLS criteria had received a physician diagnosis of RLS, and only 13% were on any RLS treatment. Interestingly, of respondents with RLS who reported receiving a physician diagnosis, those who were on medications were more likely to report symptoms at least 3 days/week, as well as depression, anxiety, and daily sleep disturbance, suggesting that treatment may not have been effective for many of these individuals.

RLS in this population was associated with significant burden. Those meeting criteria for RLS were 50% to 90% more likely to report a history of depression or anxiety disorders and to be taking medications for these conditions; likewise, participants with RLS were over twice as likely to report symptoms of sleep disturbance. These associations increased in both strength and magnitude with increasing symptom frequency, with those reporting symptoms at least 3×/week indicating the highest prevalence of depression, anxiety, and sleep disturbance, and the shortest average sleep duration.

While the cross-sectional nature of this survey study precludes determination of temporal relationships, the high RLS prevalence observed may help explain the elevated rates of both sleep disturbance and depressive disorders documented in West Virginia residents.28,29 The observed relationship of RLS with mood and sleep disorders may also be bidirectional. Poor sleep or mood may precipitate or exacerbate RLS via, for example, adverse effects on autonomic regulation, HPA axis function, neuroendocrine profiles, motor excitability, and pain processing.2

Direct comparisons of RLS prevalence across studies remain challenging due to broadly differing diagnostic criteria for RLS, differing definitions of clinically significant RLS, and wide variation in targeted populations.1,2 Nonetheless, prevalence of RLS observed in this Appalachian population was higher than that reported in prior studies of US and Western European primary care populations that used similarly stringent criteria and/or clinical confirmation to define RLS.1,12,3335

Documented prevalence of RLS in primary care settings has typically averaged higher than that reported in population cohorts or random samples from the general population, possibly reflecting overall poorer health in primary care patients.1 Primary care patients may also be more likely to seek medical care for conditions related to RLS.1,39 The definition of clinically significant RLS has varied across studies, from no symptom frequency or severity requirement36 to symptoms at least twice/week with at least moderate distress.33,40 In this study, RLS symptoms 1-2×/week were associated with significantly elevated disturbance of both sleep and mood, suggesting that RLS may be associated with substantial burden even in those with relatively low frequency of symptoms. While research assessing the potential dose-response associations of RLS severity to sleep quality and affective disorders is sparse, several previous studies have documented elevated sleep and mood disturbance in those with RLS.1,2,41,42

Consistent with most, but not all previous studies,2 we found RLS prevalence to be elevated in women and older adults, appearing to peak in the sixth decade. Relatively few studies have specifically examined the association of RLS to socioeconomic indices, including education, income, and employment, and even fewer have assessed the relation of RLS to race/ ethnicity or marital status.1,43 In this investigation, participants with RLS were less likely to be college educated and more likely to be lower income, in agreement with some,20,21,23 but not other studies21,44,45 in the general population. Likewise, in agreement with a state-wide survey study of 1,803 Kentucky residents,21 but in contrast to findings from a second large European study,22 we found no association between RLS and marital status. Those who were unemployed or disabled were also significantly more likely to meet RLS criteria in this population of WV primary care patients. Three studies have examined the link of RLS to unemployment,22,23,43 two suggesting elevated RLS prevalence22,43 and a third, increased risk for incident RLS23 in unemployed adults; to our knowledge, the association of disability has not been investigated in previous studies. Our findings of reduced RLS prevalence in minority participants are in agreement with data from a previous study in two large US adult cohorts,46 although no differences between blacks and non-Hispanic whites were reported in another study of 1,028 Baltimore adults.47

While caffeine consumption is often cited as an exacerbating or precipitating factor for RLS,48 evidence to date is sparse, with no studies to date documenting a significant positive association.22,44,49 Consistent with findings of recent population-based studies,44,49 we likewise found no association between RLS and caffeine consumption. In contrast to some2022,24,43,50 but not other previous studies,44,49,51,52 RLS was not significantly related to smoking in this population after adjustment for other factors, although univariate analysis suggested a positive association. Consistent with findings from several previous investigations,2,17,53,54 RLS was strongly and positively associated with comorbidity in this study. Likewise, the strong, positive link between RLS and obesity observed in this study is in agreement with most, although not all previous studies.2,46,50,55

Strengths and Limitations

Strengths of this survey study include the relatively large number of primary care patients in our clinic-based sample, and the high study participation rates in an Appalachian region. We used established international criteria to define RLS4 and questions based on a previously validated diagnostic questionnaire,30 assessed symptom frequency, and asked specific questions regarding the presence of potential mimics to reduce risk of misclassification.56 Information on symptom frequency allowed evaluation of potential dose-response associations. In addition, participants provided comprehensive self-report information on numerous potential correlates and confounders, including demographics, lifestyle characteristics, mood and sleep patterns, and health-related factors. The survey was presented as a study to examine typical sleep patterns and correlates in Morgantown area residents, with no mention of sleep deficits, mood disorders, or RLS; thus participation bias associated with either RLS or associated impairment in sleep and mood, while possible, is unlikely.

Limitations of this pilot survey are also several. Participants were restricted to primary care patients from a predominantly rural, Appalachian community, and findings may thus not be generalizable to other populations. We lacked data on certain lifestyle characteristics, including alcohol consumption, which has been associated with RLS in at least two prior investigations.21,22 Although we did have information on diagnosed anemia, we lacked data on blood levels of ferritin, hemoglobin levels, or other analytes potentially related to RLS. In addition, while we collected general information on medication use for health chronic conditions, including depression and anxiety, we did not collect information on specific medications (e.g., tricyclic antidepressants or selective serotonin uptake inhibitors) or on medication use for other serious mental health conditions (e.g., schizophrenia or psychosis) which could potentially exacerbate RLS.56 However, the evidence regarding the association of psychotropic medication to RLS remains inconsistent. For example, while some investigators report SSRIs can precipitate RLS,57 other studies have documented no association58 or a reduction in RLS symptoms.59 Moreover, excluding those on medication for depression or anxiety (which would be expected to capture most psychotropics thought to be linked to RLS56) did not appreciably alter prevalence estimates in this population, and excluding those on medication for any chronic condition yielded only modest reductions in RLS prevalence, suggesting that medications are unlikely to account for the high rates of RLS observed in this population.

Exclusion of participants with missing data on covariates may have introduced selection bias. Unmeasured confounding might also help explain our findings, although our ability to control for a large number of both known and potential factors previously linked to RLS renders this possibility less probable. Thirteen respondents reported a diagnosis of RLS, but did not meet current symptom criteria. While some of these participants may have been misdiagnosed with RLS, others may have experienced RLS, for example, only during pregnancy or in association with since corrected anemia. One of the 13 also reported taking RLS medications, which may have led to symptom relief. Although based on questions adapted from a validated questionnaire30 and incorporating questions designed to exclude common mimics, RLS determination was reliant on self-report, and some degree of diagnostic error is thus possible. However, affirmative response to all four essential criteria, coupled with the absence of discomfort due to leg cramps or positional discomfort renders misdiagnosis less likely.56,60 In addition, excluding from our analysis participants with specific chronic conditions linked to RLS did not appreciably alter our findings regarding either the prevalence or correlates of RLS, suggesting that these comorbid conditions are unlikely to explain the high prevalence of RLS, or the strong dose-response associations of RLS to mood and sleep impairment noted in this population. Ascertainment of medical diagnoses was based on self-report, potentially introducing bias. While our target population comprised WVU primary care patients, who are more likely to seek and receive medical care, and thus to be better informed about their health and medical conditions than a general WV population, misclassification remains possible. A validation study of a broader Appalachian population in the Ohio valley using medical records showed adequate concordance (74%) and excellent specificity (over 95%) for self-reported diabetes, and very high concordance (> 99%) for self-reported cancers (unpublished data). Nonetheless, self-report of chronic illness has been shown to be vulnerable to misclassification and especially to reduced sensitivity,6163 possibly biasing estimates of association towards the null. In addition, given that depression and other mental health disorders remain significantly underdiagnosed in US primary care and other populations,6466 depression and anxiety disorders were likely under-ascertained in this study, possibly attenuating our observed associations of these conditions to RLS.

As in most other epidemiological studies of RLS, our data are cross-sectional, precluding determination of causality. Clearly, prospective studies are needed to evaluate potential risk and causal factors underlying the development and progression of RLS, as well as the specific effects of RLS on health and well-being.

CONCLUSIONS

Findings of this preliminary anonymous survey study suggest that RLS prevalence is high in this Appalachian primary care population even when those with associated comorbidities were excluded. RLS also showed a strong, dose-response association to mood and sleep impairment, and may help explain the elevated rates of both depression and sleep deficits reported in WV residents. However, larger prospective studies are needed to investigate potential causal relationships and to enhance our still incomplete understanding regarding both the etiology and sequelae of RLS in this and other populations.

DISCLOSURE STATEMENT

This was not an industry supported study. The authors have indicated no financial conflicts of interest. This work was performed at West Virginia University, and was supported by the National Center for Complementary and Alternative Medicine [Grant Number 1-K01-AT004108 to Dr. Innes and West Virginia University (Faculty Incentive Award). The contents are solely the responsibility of the authors and do not represent the official views of West Virginia University or the National Institutes of Health.

ACKNOWLEDGMENTS

The authors thank Veronte Stubbs for her assistance in data collection.

REFERENCES

1 

Innes KE, Selfe TK, Agarwal P, authors. Prevalence of restless legs syndrome in North American and Western European populations: a systematic review. Sleep Med. 2011;12:623–34. [PubMed]

2 

Innes KE, Selfe TK, Agarwal P, authors. Restless legs syndrome and conditions associated with metabolic dysregulation, sympathoadrenal dysfunction, and cardiovascular disease risk: a systematic review. Sleep Med Rev. 2012;16:309–39. [PubMed]

3 

Walters AS, author. Toward a better definition of the restless legs syndrome. Mov Disord. 1995;10:634–42. [PubMed]

4 

Allen RP, Picchietti D, Hening WA, et al., authors. 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. Sleep Med. 2003;4:101–19. [PubMed]

5 

Reinhold T, Müller-Riemenschneider F, Willich SN, Brüggenjürgen B, authors. Economic and human costs of restless legs syndrome. Pharmacoeconomics. 2009;27:267–79. [PubMed]

6 

Happe S, Reese JP, Stiasny-Kolster K, et al., authors. Assessing health-related quality of life in patients with restless legs syndrome. Sleep Med. 2009;10:295–305. [PubMed]

7 

Earley CJ, Silber MH, authors. Restless legs syndrome: understanding its consequences and the need for better treatment. Sleep Med. 2010;11:807–15. [PubMed]

8 

Reese JP, Stiasny-Kolster K, Oertel WH, Dodel RC, authors. Health-related quality of life and economic burden in patients with restless legs syndrome. Expert Rev Pharmacoecon Outcomes Res. 2007;7:503–21. [PubMed]

9 

Abetz L, Allen R, Follet A, et al., authors. Evaluating the quality of life of patients with restless legs syndrome. Clin Ther. 2004;26:925–35. [PubMed]

10 

Hening WA, Allen RP, Chaudhuri KR, et al., authors. Clinical significance of RLS. Mov Disord. 2007;22 Suppl 18:S395–400. [PubMed]

11 

Garcia-Borreguero D, author. Time to REST: epidemiology and burden. Eur J Neurol. 2006;13 Suppl 3:15–20. [PubMed]

12 

Hening W, Walters AS, Allen RP, Montplaisir J, Myers A, Ferini-Strambi L, authors. Impact, diagnosis and treatment of restless legs syndrome (RLS) in a primary care population: the REST (RLS epidemiology, symptoms, and treatment) primary care study.[see comment]. Sleep Med. 2004;5:237–46. [PubMed]

13 

Hornyak M, Kopasz M, Berger M, Riemann D, Voderholzer U, authors. Impact of sleep-related complaints on depressive symptoms in patients with restless legs syndrome. J Clin Psychiatry. 2005;66:1139–45. [PubMed]

14 

Hornyak M, author. Depressive disorders in restless legs syndrome: epidemiology, pathophysiology and management. CNS Drugs. 2010;24:89–98. [PubMed]

15 

Sateia MJ, author. Update on sleep and psychiatric disorders. Chest. 2009;135:1370–9. [PubMed]

16 

Winkelman JW, author. Considering the causes of RLS. Eur J Neurol. 2006;3:8–14.

17 

Walters AS, Rye DB, authors. Review of the relationship of restless legs syndrome and periodic limb movements in sleep to hypertension, heart disease, and stroke. Sleep. 2009;32:589–97. [PubMed Central][PubMed]

18 

Smith JE, Tolson JM, authors. Recognition, diagnosis, and treatment of restless legs syndrome. J Am Acad Nurs Pract. 2008;20:396–401.

19 

Kushida CA, Nichols DA, Simon RD, et al., authors. Symptom-based prevalence of sleep disorders in an adult primary care population. Sleep Breath. 2000;4:9–14. [PubMed]

20 

Berger K, Luedemann J, Trenkwalder C, John U, Kessler C, authors. Sex and the risk of restless legs syndrome in the general population. Arch Intern Med. 2004;164:196–202. [PubMed]

21 

Phillips B, Young T, Finn L, Asher K, Hening WA, Purvis C, authors. Epidemiology of restless legs symptoms in adults.[see comment]. Arch Intern Med. 2000;160:2137–41. [PubMed]

22 

Ohayon MM, Roth T, authors. Prevalence of restless legs syndrome and periodic limb movement disorder in the general population. J Psychosom Res. 2002;53:547–54. [PubMed]

23 

Szentkiralyi A, Fendrich K, Hoffmann W, Happe S, Berger K, authors. Socio-economic risk factors for incident restless legs syndrome in the general population. J Sleep Res. 2012;21:561–8. [PubMed]

24 

Sevim S, Dogu O, Kaleagasi H, Aral M, Metin O, Camdeviren H, authors. Correlation of anxiety and depression symptoms in patients with restless legs syndrome: a population based survey. J Neurol Neurosurg Psychiatry. 2004;75:226–30. [PubMed Central][PubMed]

25 

Thoenen E, author. The burden of arthritis in West Virginia. Charleston: West Virginia Bureau for Public Health. February, 2006.

26 

Centers for Disease Control and Prevention. National Diabetes Surveillance System. 2011. Accessed August 15 2011.

27 

Sherry B, Blanck H, Galuska D, Pan L, Dietz W, Balluz L, authors. Vital Signs: state-specific obesity prevalence among adults --- United States, 2009. MMWR Morb Mortal Wkly Rep. 2010;59:1–5. [PubMed]

28 

Gonzalez O, Berry JT, McKnight-Eily LR, et al., authors. Current depression among adults-United States, 2006 and 2008 (Reprinted from MMWR, vol 59, pg 1229-1235, 2010). JAMA. 2010;304:2233–5.

29 

McKnight-Eily LR, Liu Y, Perry GS, et al., authors. Perceived insufficient rest or sleep among adults-United States, 2008 (Reprinted from MMWR, vol 58, pg 1175-1179, 2009). JAMA. 2009;302:2532.

30 

Allen RP, Burchell BJ, MacDonald B, Hening WA, Earley CJ, authors. Validation of the self-completed Cambridge-Hopkins questionnaire (CH-RLSq) for ascertainment of restless legs syndrome (RLS) in a population survey. Sleep Med. 2009;10:1097–100. [PubMed]

31 

Centers for Disease Control and Prevention. National Health and Nutrition Examination Survey: 2005-2006 data documentation, codebook, and frequencies. 2008. Accessed March 29 2013. http://www.cdc.gov/nchs/nhanes/nhanes2005-2006/SLQ_D.htm.

32 

U.S. Census Bureau. State and County QuickFacts 2011. http://quickfacts.census.gov/qfd/states/54000.html.

33 

Allen RP, Stillman P, Myers AJ, authors. Physician-diagnosed restless legs syndrome in a large sample of primary medical care patients in western Europe: Prevalence and characteristics. Sleep Med. 2010;11:31–7. [PubMed]

34 

Möller C, Wetter TC, Köster J, Stiasny-Kolster K, authors. Differential diagnosis of unpleasant sensations in the legs: Prevalence of restless legs syndrome in a primary care population. Sleep Med. 2010;11:161–6. [PubMed]

35 

O'Keeffe ST, Egan D, Myers A, Redmond S, authors. The frequency and impact of restless legs syndrome in primary care. Ir Med J. 2007;100:539–42. [PubMed]

36 

Nichols DA, Allen RP, Grauke JH, et al., authors. Restless legs syndrome symptoms in primary care: a prevalence study. Arch Intern Med. 2003;163:2323–9. [PubMed]

37 

Alattar M, Harrington JJ, Mitchell CM, Sloane P, authors. Sleep problems in primary care: A North Carolina family practice research network (NC-FP-RN) study. J Am Board Fam Med. 2007;20:365–74. [PubMed]

38 

Schwegler K, Klaghofer R, Nirrko AC, Mathis J, Hersberger KE, Bloch KE, authors. Sleep and wakefulness disturbances in Swiss pharmacy customers. Swiss Med Wkly. 2006;136:149–54. [PubMed]

39 

Ohayon MM, O'Hara R, Vitiello MV, authors. Epidemiology of restless legs syndrome: a synthesis of the literature. Sleep Med Rev. 2012;16:283–95. [PubMed Central][PubMed]

40 

Allen RP, Walters AS, Montplaisir J, et al., authors. Restless legs syndrome prevalence and impact: REST general population study. Arch Intern Med. 2005;165:1286–92. [PubMed]

41 

Winkelmann J, Prager M, Lieb R, et al., authors. “Anxietas tibiarum”. Depression and anxiety disorders in patients with restless legs syndrome. J Neurol. 2005;252:67–71. [PubMed]

42 

Lee HB, Hening WA, Allen RP, et al., authors. Restless legs syndrome is associated with DSM-IV major depressive disorder and panic disorder in the community. J Neuropsychiatry Clin Neurosci. 2008;20:101–5. [PubMed]

43 

Phillips B, Hening W, Britz P, Mannino D, authors. Prevalence and correlates of restless legs syndrome: results from the 2005 National Sleep Foundation Poll. Chest. 2006;129:76–80. [PubMed]

44 

Hadjigeorgiou GM, Stefanidis I, Dardiotis E, et al., authors. Low RLS prevalence and awareness in central Greece: an epidemiological survey. Eur J Neurol. 2007;14:1275–80. [PubMed]

45 

Bjorvatn B, Leissner L, Ulfberg J, et al., authors. Prevalence, severity and risk factors of restless legs syndrome in the general adult population in two Scandinavian countries. Sleep Med. 2005;6:307–12. [PubMed]

46 

Gao X, Schwarzschild MA, Wang H, Ascherio A, authors. Obesity and restless legs syndrome in men and women. Neurology. 2009;72:1255–61. [PubMed Central][PubMed]

47 

Lee HB, Hening WA, Allen RP, Earley CJ, Eaton WW, Lyketsos CG, authors. Race and restless legs syndrome symptoms in an adult community sample in east Baltimore. Sleep Med. 2006;7:642–5. [PubMed]

48 

Ryan M, Slevin JT, authors. Restless legs syndrome. Am J Health Syst Pharm. 2006;63:1599–612. [PubMed]

49 

Winkelman JW, Shahar E, Sharief I, Gottlieb DJ, authors. Association of restless legs syndrome and cardiovascular disease in the Sleep Heart Health Study. Neurology. 2008;70:35–42. [PubMed]

50 

Benediktsdottir B, Janson C, Lindberg E, et al., authors. Prevalence of restless legs syndrome among adults in Iceland and Sweden: Lung function, comorbidity, ferritin, biomarkers and quality of life. Sleep Med. 2010;11:1043–8. [PubMed]

51 

Takaki J, Nishi T, Nangaku M, et al., authors. Clinical and psychological aspects of restless legs syndrome in uremic patients on hemodialysis. Am J Kidney Dis. 2003;41:833–9. [PubMed]

52 

Gamaldo CE, Benbrook AR, Allen RP, Scott JA, Henning WA, Earley CJ, authors. Childhood and adult factors associated with restless legs syndrome (RLS) diagnosis. Sleep Med. 2007;8:716–22. [PubMed]

53 

Kim KW, Yoon I-Y, Chung S, et al., authors. Prevalence, comorbidities and risk factors of restless legs syndrome in the Korean elderly population - results from the Korean Longitudinal Study on Health and Aging. J Sleep Res. 2010;19(1 Pt 1):87–92. [PubMed]

54 

Ulfberg J, Bjorvatn B, Leissner L, et al., authors. Comorbidity in restless legs syndrome among a sample of Swedish adults. Sleep Med. 2007;8:768–72. [PubMed]

55 

Buda BL, Tóth GA, authors. Restless legs syndrome and obesity in Hungarian young adult men. Papers on Anthropology. 2008;17:38–48.

56 

Garcia-Borreguero D, Stillman P, Benes H, et al., authors. Algorithms for the diagnosis and treatment of restless legs syndrome in primary care. BMC Neurol. 2011;11:28. [PubMed Central][PubMed]

57 

Rottach KG, Schaner BM, Kirch MH, et al., authors. Restless legs syndrome as side effect of second generation antidepressants. J Psychiatr Res. 2008;43:70–5. [PubMed]

58 

Brown LK, Dedrick DL, Doggett JW, Guido PS, authors. Antidepressant medication use and restless legs syndrome in patients presenting with insomnia. Sleep Med. 2005;6:443–50. [PubMed]

59 

Dimmitt SB, Riley GJ, authors. Selective serotonin receptor uptake inhibitors can reduce restless legs symptoms. Arch Intern Med. 2000;160:712. [PubMed]

60 

Benes H, Walters AS, Allen RP, Hening WA, Kohnen R, authors. Definition of restless legs syndrome, how to diagnose it, and how to differentiate it from RLS mimics. Mov Disord. 2007;22 Suppl 18:S401–8. [PubMed]

61 

Goebeler S, Jylha M, Hervonen A, authors. Self-reported medical history and self-rated health at age 90. Agreement with medical records. Aging Clin Exp Res. 2007;19:213–9. [PubMed]

62 

Goldman N, Lin IF, Weinstein M, Lin YH, authors. Evaluating the quality of self-reports of hypertension and diabetes. J Clin Epidemiol. 2003;56:148–54. [PubMed]

63 

Molenaar EA, Van Ameijden EJ, Grobbee DE, Numans ME, authors. Comparison of routine care self-reported and biometrical data on hypertension and diabetes: results of the Utrecht Health Project. Eur J Public Health. 2007;17:199–205. [PubMed]

64 

Robinson WD, Geske JA, Prest LA, Barnacle R, authors. Depression treatment in primary care. J Am Board Fam Pract. 2005;18:79–86. [PubMed]

65 

US Preventive Services Task Force. US Preventive Services Task Force now finds sufficient evidence to recommend screening adults for depression. Press release. 2002. Accessed March 25 2013. http://www.ahrq.gov/news/press/pr2002/deprespr.htm.

66 

Noyes K, Liu HS, Lyness JM, Friedman B, authors. Medicare beneficiaries with depression: comparing diagnoses in claims data with the results of screening. Psychiatr Serv. 2011;62:1159–66. [PubMed]