An Epidemiologic Study Of Restless Legs Syndrome Among Adults And The Sleep Characteristics Of Restless Legs Syndrome

Part I An Epidemiologic Study of Restless Legs Syndrome among Chinese adults in a rural communityObjectives:The primary objective of this study was to investigate the prevalence and risk factors of restless legs syndrome (RLS) in an adult Chinese population living in a rural community. We also aimed to determine the predictive diagnostic value of the 4-item screening questionnaire for RLS in this population.Methods:A total of 2941 adults >18 years old in 2 rural community of Shanghai were sampled by random cluster sampling. This study was designed as a 2-phase survey. In phase 1 we performed a face-to-face interview of eligible individuals living in a rural community in Shanghai using a 4-item screening questionnaire. In phase 2, sleep specialists performed a phone interview of the individuals who screened positive to diagnosis RLS.Results:Forty-one RLS cases were confirmed among 2941 eligible individuals 18 years of age or older in the study community. The prevalence of RLS was 1.4%(95% confidence interval (CI)=1.0-1.9%), with a significantly higher rate observed in females (1.9%[95%CI=1.3-2.7%]) than that in males (0.9% [95%CI=0.5-1.5%], p=0.019). The prevalence rate increased significantly with age, from 0.2%(95% CI=0.08-0.6%) in those 18-39 years old to 4.1%(95% CI=2.1-7.9%) in those ≥70 years old (p<0.001). Only 21.9% RLS patients had been diagnosed by a physician. The multivariate logistic regression analysis indicated that gastritis (OR=2.96; 95% CI:1.27-6.90; P=0.012), anemia (OR=6.93; 95% CI:2.78-17.30; P<0.001), and hypertension (OR=4.10; 95% CI:1.88-8.92; P<0.001) were risk factors for RLS. For the female population, gastritis (OR= 3.28; 95% CI:1.05-10.24; P=0.041) and anemia (OR=10.86; 95% CI:3.87-30.48; P<0.001) were risk factors of RLS, and for the male population, only hypertension (OR=7.18; 95% CI:1.74-29.58; P=0.006) was the risk factor of RLS. The sensitivity and specificity of the 4-item screening questionnaire used in this study were 63.4% and 97.5%, respectively. Its positive predictive value was 83.9%, and its negative predictive value was 92.8%.Conclusion:The prevalence of RLS is 1.4% among Chinese adults living in rural Shanghai, which was similar to most Asian population, but lower than Western countries. The prevalence of RLS increased significantly with advancing age. Different genders had different risk factors. Among the female population, gastritis and anemia were risk factors of RLS, while for the male population, only hypertension was a risk factor of RLS. The positive predictive value and negative predictive value of the 4-item screening questionnaire used in this study were 83.9%, and 92.8%, respectively. Further population-based studies using the 4-item screening questionnaire should be aware its false positive rate and false negative rate. The rate of right diagnosis in our nation is low. Therefore, there is a need to increase the awareness regarding RLS among both medical professionals and the general population.Part II Subjective sleep and awakening quality and polysomnographic studies in restless legs syndrome (RLS) patients as compared with normal controlsObjectives:To investigate the objective and subjective sleep and awakening quality in restless legs syndrome (RLS), and test the correlation between RLS severity (IRLS scores) and sleep laboratory measurements.Methods:30 RLS patients free of psychotropic drugs were studied as compared with age-and sex-matched normal controls, utilizing clinical evaluations by the BECK Depression Inventory (BDI) and BECK Anxiety Inventory (BAI), Chalder Fatigue Scale-14 (FS-14), RLS-Quality of life(RLSQoL), the Pittsburgh Sleep Quality Index (PSQI), and the Epworth Sleepiness Scale to investigate the subjective sleep and awakening quality. Objective sleep and awakening quality were evaluated utilizing PSG in the sleep laboratory.Results:Scores of the PSQI, BDI, and FS-14 were found increased in RLS patient groups; RLS severity(IRLS) correlated significantly with PSQI, FS-14 and RLSQoL. RLS patients exhibited shorter total sleep time, lower sleep efficiency, higher arousal index. During the sleep period time, percentage of wake and sleep stage 1 were increased in RLS patients. The PLMS index were markedly increased in the RLS group. IRLS correlated significantly with PLMS index. There was no correlation between IRLS and any other sleep variable during PSG.Conclusions:RLS negatively affects objective and subjective sleep and awakening quality. There was a correlation between IRLS and subjective sleep quality and objective parameters of motor dysfunction such as PLMS-index.Part Ⅲ Time distribution of periodic periodic leg movements (PLM) during sleep in patients with restless legs syndromeObjective:To analyze the night distribution of periodic periodic leg movements (PLM) during sleep in patients with restless legs syndrome (RLS) and compare the results with those obtained in subjects with PLMD, RBD and narcolepsy.Methods:We recruited 20 patients with RLS,20 with RBD,20 with PLMD, and 12 with narcolepsy/cataplexy. The hourly distribution and sleep cycle distribution of their periodic leg movements (PLM) during sleep were analyzed.Results:The hourly distribution and sleep cycle distribution of the number of PLM per hour of sleep were both bell shaped in RLS, whereas patients with RBD and PLMD showed a progressive decrease throughout the night and patients with narcolepsy was relatively evenly distributed across the night with slightly greater activity in the middle of the night.Conclusion:The periodic periodic leg movements (PLM) during sleep in patients with restless legs syndrome had a special night distribution, which improving the diagnostic specificity of RLS.Part IV The utilization of Suggested Immobilization Tests in restless legs syndromeObjectives:To evaluate the characteristics of leg movements and leg discomfort experienced by patients with the restless legs syndrome (RLS) during wakefulness using the standard suggested immobilization test (SIT) and modified SIT.Methods:Thirty patients with RLS and thirty control subjects were selected in this research. Two immobilization tests have been described to assess leg restlessness in these patients. In the first standard SIT, the control subjects and 15 patients sits in bed with his or her legs outstretched while electromyograms are recorded from right and left anterior tibialis muscles scheduled at 21:00-21:30 and lasted 1 hour; In the modified SIT, the other 15 patients scheduled when the symptoms at their maximum severity with the use of symptom diaries. In the current study, the standard SIT were compared in patients with RLS and normal control subjects matched for age and sex; and the standard SIT and modified SIT were compared in these RLS patients. We also used the two SITs to evaluate the effects of immobility on leg discomfort and leg movements experienced by these patients with RLS and control subjects. Results:More leg movements were seen in patients than in controls during standard SIT. Patients with RLS showed a higher leg discomfort score and a greater PLM index than control subjects. Compared with standard SIT, Patients with modified SIT had a similar IRLS、leg discomfort score and PLM index, but a higher sensitivity for leg discomfort. Immobility significantly worsens leg discomfort in patients with both RLS groups but not in controls. However, immobility significantly worsens PLMW index in patients with both RLS groups and controls. We also found IRLS correlated significantly with PLMW index、MDS using modified SIT but not standard SIT.Conclusion:These results validate the use of the modified SIT as a diagnostic and research tool for RLS and confirm the contention of the International RLS study group that RLS symptoms worsen at rest and the time of administration of the SIT could significantly influence leg discomfort score.Conclusions1. The prevalence of RLS is 1.4% among Chinese adults living in rural Shanghai. The RLS prevalence in females was twice as high as that in males. The prevalence rate increased significantly with age. Only 21.9% RLS patients had been diagnosed by a physician.2. The multivariate logistic regression analysis indicated that gastritis, anemia, and hypertension were risk factors for RLS. For the female population, gastritisand anemia were risk factors of RLS, and for the male population, only hypertension was the risk factor of RLS.3. The sensitivity of the screening questionnaire used in this study was low, the diagnosis based only on the screening questionnaire suggested by the IRLSSG may underestimate the prevalence of RLS.4. Scores of the PSQI, BDI, and FS-14 were found increased in RLS patient groups; RLS severity(IRLS) correlated significantly with PSQI, FS-14 and RLSQoL.5. RLS patients exhibited shorter total sleep time, lower sleep efficiency, higher arousal index. During the sleep period time, percentage of wake and sleep stage 1 were increased in RLS patients. The PLMS index were markedly increased in the RLS group. IRLS correlated significantly with PLMS index.6. The periodic periodic leg movements (PLM) during sleep in patients with restless legs syndrome had a special night distribution, which improving the diagnostic specificity of RLS.7. Modified SIT is a sensitive diagnostic and research tool for RLS, the time of administration of the SIT could significantly influence leg discomfort score.