Clinical efficacy of ferric carboxymaltose treatment in patients with restless legs syndrome

ObjectiveThere have been three randomized, placebo-controlled, double-blind studies of intravenous iron in restless legs syndrome (RLS), with differing outcomes. The one positive study used ferric carboxymaltose (FCM) at a total dose of 1000 mg. The purpose of this study was to replicate and extend the findings from the prior FCM study.MethodsNon-anemic, idiopathic RLS patients were enrolled in a randomized, double-blinded, placebo-controlled study and received either 1000 mg FCM or placebo as a single infusion (phase I). Subjects were off any RLS medications for at least two weeks prior to baseline assessment. The primary outcome variable was change from baseline at week 6 on the International Restless Legs Syndrome Severity (IRLSS) scale and a subject-completed, visual analog scale (VAS) of severity. Phase II of the study involved long-term (30 weeks) follow-up after completion of the six-week efficacy phase.ResultsAt week 6 postinfusion, FCM compared to placebo recipients showed significantly greater change from baseline for both primary outcome measures (IRLSS scale, −11.9 ± 8.04 vs −7.88 ± 5.89, p = 0.03; VAS, −40.6 ± 22.7 vs −21.3 ± 20.0, p = 0.001). None of the secondary outcome variables showed a significant difference at week 6. After six weeks of treatment, the FCM group had 19 (59.4%) responders, of which 12 had IRLSS scores <10 (“remitters”). Twelve (37.5%) of the 32 subjects treated with iron in phase I remained free of further RLS medications at 30 weeks. There were no serious adverse events observed in this study.ConclusionTwo studies now support the value of FCM treatment both in the short term (six weeks) and long term (30 weeks) for improving RLS symptoms.     

Clinical efficacy and safety of intravenous ferric carboxymaltose treatment of pediatric restless legs syndrome and periodic limb movement disorder

BackgroundIron supplementation is the most commonly considered treatment option for children with restless legs syndrome (RLS) or periodic limb movement disorder (PLMD); however, there is a scarcity of evidence on the effectiveness of intravenous preparations. In this study, we evaluated the effectiveness and tolerability of intravenous ferric carboxymaltose (IV FCM) on clinical symptoms and iron indices in children with RLS or PLMD.MethodsThis was a single-center retrospective data analysis. Children with a diagnosis of RLS or PLMD, who underwent a single infusion of IV FCM, were included. Clinical Global Impression (CGI) Scale scores, serum ferritin, and serum iron profile at baseline and after eight weeks post infusion were obtained. Adverse effects were assessed.ResultsThirty-nine children received IV FCM, 29 with RLS and 10 with PLMD. Pre-infusion CGI-Severity revealed moderate illness, with post-infusion CGI-Improvement between “very much improved” and “much improved”. Ferritin increased from 14.6 μg/L ± 7.01 to 112.4 μg/L ± 65.86 (p < 0.00001), together with improvements in iron, total iron binding capacity, and transferrin levels from baseline to post-treatment. When compared to children with RLS, those with PLMD had a similar improvement in clinical symptoms and laboratory parameters. Seven subjects (14.3%) experienced one or two adverse events; all were mild.ConclusionsChildren with RLS and PLMD responded to IV iron supplementation with improvement in both clinical severity and laboratory parameters. Treatment was well tolerated. Although larger, randomized-controlled trials are needed, IV FCM appears to be a promising alternative to oral iron supplementation for the treatment of pediatric RLS or PLMD.     

Patient characteristics predicting responses to intravenous ferric carboxymaltose treatment of restless legs syndrome

BackgroundSignificant benefit of intravenous ferric carboxymaltose (FCM) treatment for restless legs syndrome (RLS) has been well-established. However, no clinical indicators predicting treatment response of RLS have been established. This study aimed to determine factors predicting outcome of clinical FCM treatment of RLS patients.MethodsData were retrospectively reviewed from all patients who received FCM treatment for RLS from April 2016 to April 2019. These data included: detailed history, international RLS scale score (IRLS), questionnaires, comorbidity, and previous RLS medication use. Morning fasting serum iron, ferritin, and total iron-binding capacity were measured before and at four weeks after treatment. RLS patients with possible secondary RLS were identified by reviewing the medical histories. This included patients with iron deficiency anemia, lumbosacral radiculopathy, and gastrectomy. Primary RLS included those with no indication of secondary medical factors contributing to RLS. Treatment response was assessed using the IRLS and clinical ratings at four weeks after FCM administration. Patients with a greater than 40% decrease in IRLS were classified as responders.ResultsThe study comprised 164 patients with IRLS and clinical ratings obtained before and at four weeks after intravenous (IV) iron. Treatment responses differed considerably between diagnostic groups of RLS. Percentage responding was: 64.7% (66 of 102) for patients with primary RLS, 90.9% (10 of 11) with gastrectomy, 91.3% (21 of 23) with iron deficiency anemia and 39.3% (11 of 28) with lumbosacral radiculopathy. When responders were compared to non-responders in primary RLS patients, responders had significantly lower serum iron (80.5 ± 26.7 vs. 95.8 ± 30.5 μg/dL, p = 0.022) and percentage transferrin saturation (%TSAT) (25.4 ± 9.6 vs. 30.5 ± 10.5%, p = 0.026) in females, but not males. Logistic regression controlling for major subject variables showed that %TSAT significantly predicted response. (odds ratio [OR]: 0.955, confidence interval: 0.913–0.998, p = 0.040).ConclusionIntravenous FCM in moderate to severe RLS patients is beneficial as a first-line or add-on treatment, particularly for patients with compromised peripheral iron state. Overall, lower %TSAT predicted better chance of responding to the IV iron treatment especially for females.     

Randomized,placebo-controlled trial of ferric carboxymaltose in restless legs syndrome patients with iron deficiency anemia

ObjectiveIntravenous ferric carboxymaltose (FCM) has been shown to be efficacious in treating restless legs syndrome (RLS) symptoms in non-anemic patients. The aim of this study was to evaluate the effectiveness of FCM in treating RLS symptoms in patients who also had an iron deficiency anemia (IDA).MethodsThis is a randomized, double-blinded, placebo-controlled study. Subjects with RLS and IDA were enrolled. Subjects received an infusion of either 1500 mg FCM or placebo in Phase I. The primary outcomes were a change-from-baseline at week six on the International Restless Legs Syndrome Study Group scale (IRLS). Phase II of the study involved long-term (52 weeks) follow-up, for those who responded to treatment in the prior phase, with the potential for further treatment if symptoms returned.ResultsWe enrolled 29 RLS patients with IDA (15 FCM and 14 placebo). At week six post-infusion, FCM compared to placebo group showed significant improvement from baseline in IRLS score (−13.47 ± 7.38 vs. 1.36 ± 3.59). Among secondary outcome variables, quality of sleep showed significant improvement from baseline in the FCM group. 61% of subjects remained off RLS medications at the Phase II, week-52 endpoint. There were no serious adverse events observed in the study.ConclusionThe study showed significant efficacy and safety of FCM 1500 mg treatment both in the short term (6 weeks) and long term (52 weeks) in RLS patients with IDA.     

Intravenous iron sucrose for restless legs syndrome in pregnant women with low serum ferritin

We report on two pregnant women who either had de novo restless legs syndrome (RLS) or had marked enhancement of preexisting RLS symptoms during pregnancy. Both patients had ferritin values <50 μg/L at baseline. The patients had relevant sleep disorders and daytime symptoms caused by RLS. The women were treated in an open paradigm with intravenous iron sucrose. A few weeks after therapy, both patients experienced a significant reduction or even remission of RLS symptoms. Their quality of life and sleep substantially improved and no treatment-related adverse effects were observed. According to our initial experience, intravenous iron sucrose administration appears to be an effective therapy in RLS patients with low ferritin values during pregnancy.     

Long-term efficacy and safety of gabapentin enacarbil in Japanese restless legs syndrome patients

Several short- and long-term studies conducted in Europe/North America have demonstrated good efficacy and tolerability of 600-1800 mg gabapentin enacarbil (GEn). However, no studies have evaluated the efficacy of long-term treatment with GEn in Asian patients. Therefore, the objective of this study was to evaluate the efficacy and safety of long-term treatment with GEn in Japanese patients with restless legs syndrome (RLS) in a multicenter open-label study. RLS patients aged 20-80 years were allocated to receive oral GEn 1200 mg/day for a treatment period of 52 weeks. International Restless Legs Syndrome Scale (IRLS) score, investigator- and patient-rated Clinical Global Impression (CGI) scores, Pittsburgh Sleep Quality Index (PSQI) total scores and subscores, and short form (SF)-36 subscores were assessed, and adverse events (AEs) were monitored. In 181 patients (mean age, 54.9±12.2 years; BMI, 23.0±2.6 kg/m2) IRLS score decreased from 24.4±0.4 at baseline to 6.3±0.6 at week 52, with a reduction of -18.0±0.6. The IRLS responder rate was 80.3% at week 52. ICGI and PCGI responder rates were 87.1% and 87.1%, respectively. PSQI and SF-36 also showed significant improvements. AEs were reported in 96.2% of patients but remained mild-to-moderate in nearly all the cases. Serious AEs occurred in 1.6%. Dizziness and somnolence were noted in 46.2% and 41.2% of patients, respectively, and mostly occurred during the first 4 weeks. No episodes of augmentation were reported. In conclusion, long-term treatment with GEn improved RLS symptoms as well as investigator- and patient-reported outcomes in Japanese patients with moderate-to-severe RLS, with an acceptable safety profile. Randomized, double-blind, placebo/active-controlled trials are desirable to confirm these preliminary results.     

Risk factors and prevalence rate of restless legs syndrome among pregnant women in Taiwan

BackgroundThe goal of this study was to assess the prevalence and clinical correlates of restless legs syndrome (RLS) among pregnant Taiwanese women.MethodsWe enrolled 461 pregnant women (18–45 years) admitted at Mackay Memorial Hospital for delivery from September 2010 to May 2011. The face-to-face questionnaire used to gather data included assessment of RLS diagnostic criteria, and questions related to RLS.ResultsThe overall prevalence rate of RLS among the study participants was 10.4%; 2.8% were categorized as having chronic RLS. Participants without RLS reported higher folate and iron supplement consumption than those with RLS. Multivariate analysis revealed significant associations of RLS with anemia and peptic ulcer disease. Participants with transient RLS during pregnancy reported more regular coffee consumption before pregnancy, and better sleep latency, duration, and efficiency, than those with chronic RLS. Overall, 81.2% of RLS sufferers reported sleep disturbances.ConclusionsOur study revealed highly prevalent but poorly recognized RLS among Taiwanese pregnant women. The identification of predictors such as medical comorbidities, and protectors such as folate and iron supplements, is warranted for obstetric RLS. In most cases, symptoms began during the second or third trimester and resolved within a week after delivery. Restricted coffee consumption before pregnancy is encouraged, but further evidence is needed to support this recommendation.     

Ferric carboxymaltose in patients with restless legs syndrome and nonanemic iron deficiency: A randomized trial

Background : Compromised iron status is important in restless legs syndrome pathophysiology. We compared the efficacy and tolerability of ferric carboxymaltose (single intravenous dose) versus placebo for restless legs syndrome treatment in iron‐deficient nonanemic patients. Methods : Patients with moderate to severe restless legs syndrome and serum ferritin < 75 μg/L (or serum ferritin 75‐300 μg/L and transferrin saturation < 20%) were randomized to ferric carboxymaltose (1000 mg iron) or placebo. Mean change difference between ferric carboxymaltose and placebo in International Restless Legs Syndrome Severity Scale score from baseline to week 4 was the primary end point; week 12 was a secondary end point. Results : Ferric carboxymaltose treatment (n = 59) led to nonsignificant improvement over placebo (n = 51) in International Restless Legs Syndrome Severity Scale score at week 4 (difference [95% confidence interval], ‐2.5 [‐5.93 to 1.02], P = 0.163), reaching significance by week 12 (‐4.66 [‐8.59 to ‐0.73], P = 0.021). Conclusions : In patients who responded to treatment, ferric carboxymaltose may require more time to stabilize restless legs syndrome than previously assumed. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.     

Efficacy and safety of pramipexole in restless legs syndrome

OBJECTIVE: To evaluate the efficacy and safety of pramipexole in patients with moderate to severe restless legs syndrome (RLS) METHODS: The authors conducted a 12-week, double-blind, randomized, placebo-controlled trial of fixed doses of pramipexole (0.25, 0.50, and 0.75 mg/day). Patients (N = 344) were up-titrated to their randomized dose over 3 weeks. The primary efficacy endpoints were patient ratings of symptom severity on the International RLS Study Group Rating Scale (IRLS) and clinician ratings of improvement on the Clinical Global Impressions-Improvement (CGI-I) scale. Secondary efficacy endpoints included visual analogue ratings of sleep and quality of life (QOL) RESULTS: By both primary measures, pramipexole was superior to placebo. For IRLS, the adjusted mean (SE) change from baseline to week 12 was -9.3 (1.0) for placebo, -12.8 (1.0) for 0.25 mg/day, -13.8 (1.0) for 0.50 mg/day, and -14.0 (1.0) for 0.75 mg/day (all p < 0.01). Similarly, pramipexole increased the percentage of patients with a CGI-I rating of "very much improved" or "much improved" at the end of the trial (51.2% for placebo and 74.7%, 67.9%, and 72.9% for pramipexole; all p < 0.05). Pramipexole significantly improved ratings of symptom severity, day and night, and also ratings of sleep satisfaction and QOL. Pramipexole was well tolerated: The most frequent adverse events with higher occurrence in the pramipexole group were nausea (19.0% vs 4.7%) and somnolence (10.1% vs 4.7%) CONCLUSION: As rated by patients and by clinicians, pramipexole was efficacious and safe in reducing the symptoms of restless legs syndrome.     

The treatment of restless legs syndrome with intravenous iron dextran

BACKGROUND AND PURPOSE: To evaluate the safety and efficacy of a single 1000 mg iron infusion in treating Restless Legs Syndrome (RLS). PATIENTS AND METHODS: A single 1000 mg intravenous (IV) [Am J Med Sci 31 (1999) 213] infusion of iron dextran was evaluated in an open-label study. Primary outcomes of efficacy were symptom severity assessed by global rating scale and periodic leg movements in sleep (PLMS) at 2 weeks post-infusion. Secondary outcomes included total sleep time (TST), hours/day of RLS symptoms, and changes in magnetic resonance imaging (MRI)-determined iron concentrations in the substantia nigra. Primary safety measures were reported adverse events and monthly serum ferritin levels. RESULTS: IV iron therapy significantly improved the mean global RLS symptom severity, TST, hours with RLS symptoms and PLMS, but on an individual basis failed to produce any response in 3 of the 10 subjects who were fully treated. Brian iron concentrations at 2 weeks post-infusion as determined by MRI were increased in the substantia nigra and prefrontal cortex. Serum ferritin levels showed a greater than predicted rapid linear decrease. Side effects were mild, except in one subject who developed an acute allergic reaction. CONCLUSIONS: The results in this study provide valuable information for future studies, but the efficacy and safety of IV iron treatment for RLS remain to be established in double-blind studies. The serum ferritin results suggest that greater than expected iron loss occurs after IV iron loading.     

Efficacy and safety of dopamine agonists in restless legs syndrome

ObjectiveRestless legs syndrome (RLS) is a common neurological disorder causing considerable impairment to daily living. This article is an overview of a comprehensive Cochrane meta-analysis on the efficacy and safety of dopamine agonists (DAs), the first-line treatment of RLS.MethodsCENTRAL, MEDLINE, EMBASE, PsycINFO, and CINAHL databases were searched for double-blind randomized controlled trials (RCTs) of DAs vs placebo.ResultsThirty-five placebo-controlled RCTs (total number of patients = 6954) were eligible. The likelihood of bias was considered to be low. The mean treatment duration of the RCTs was 10.3 (standard deviation 7.3) weeks, with treatment durations up to seven months. Overall, DAs showed a moderate improvement in the International RLS Severity Scale score (mean difference ?5.7 points [95% confidence interval, CI, ?6.7 to ?4.7; P < 0.00001]) and the Clinical Global Impression-Improvement response (risk ratio 1.44 [95% CI 1.34–1.54; P < 0.00001]) compared with placebo. Periodic limb movements decreased by ?22.38/h (95% CI ?27.8 to ?16.9; P < 0.00001) for DAs compared with placebo. Sleep quality and disease-specific quality of life increased slightly to moderately. Safety data confirmed the established safety characteristics of DAs. Augmentation, a specific side-effect of dopaminergic treatment of RLS, was not assessed adequately.ConclusionsThis meta-analysis showed that DAs have moderate efficacy in the treatment of RLS. Actively controlled and long-term studies are still lacking. Large-scale comparative studies are needed to identify the most efficient treatments for this chronic disorder.     

Transdermal lisuride: short-term efficacy and tolerability study in patients with severe restless legs syndrome

BACKGROUND AND PURPOSE: Restless legs syndrome (RLS) patients suffer from symptoms not only at bedtime but also with variable circadian patterns. Transdermal application forms of dopamine agonists are expected to lead to a stable plasma concentration of the active drug which could ease treatment for RLS patients with daytime symptoms and avoid side effects of oral dopaminergic therapies. PATIENTS AND METHODS: In this controlled pilot study, 10 patients (six females, four males, mean age 58 years) with severe and long-lasting idiopathic RLS were treated during an initial open-label phase for 2 weeks either with one (n=3 patients) or, if required, two patches of lisuride every other day (dose per patch: 3mg lisuride, nominal effective release rate 7.0 microg lisuride/h). Patients were then randomized to double-blind treatment with lisuride (n=5) or placebo (n=4) for 1 week. RESULTS: Severity of RLS clearly improved during open-label and double-blind treatment with lisuride but became worse under placebo according to the International Restless Legs Syndrome Study Group Rating Scale (IRLS), RLS-6, and Clinical Global Impressions (CGIs) scales, and actigraphy assessments (periodic leg movement index) in the 1-week double-blind period. CONCLUSION: The explorative findings of this small controlled study suggest that lisuride patches might be an efficacious treatment for RLS patients without clinically relevant tolerability problems.     

Investigating the response to intravenous iron in restless legs syndrome: an observational study

ObjectiveTo investigate the effect of intravenous (IV) iron (500 mg ferric carboxymaltose [FCM] as a single dose) on restless legs syndrome (RLS) severity on a day-to-day basis.MethodsTwenty patients with RLS and absolute or functional iron deficiency or low normal serum ferritin (<45 μg/l) were included. Change of RLS severity was evaluated using the International RLS severity scale (IRLS) and the RLS-severity diary (RLS-SD) which evaluates symptom severity over a 6-h period on an 11-point numerical Likert scale, four times a day.ResultsTwelve patients reported that IV FCM improved RLS (“responders”). IRLS score decreased from 30.1 (±5.9) to 23.07 (±9.5) (p = 0.001) in the whole group and from 28.3 (±6.1) to 18.3 (±8.0) (p = 0.002) in the responder group three weeks after IV FCM treatment. A clinically relevant effect of IV iron on RLS severity could be seen as early as day eight. The responder group differed from the non-responder group in tendency by being younger (p = 0.064), having a lower serum ferritin level at baseline (p = 0.097), and presenting a lower number of comorbid conditions.ConclusionsFCM led to a considerable improvement in RLS in the responder group within about one week. These findings are clinically relevant, especially for patients with severe RLS symptoms and iron deficiency, since a change or uptitration of RLS-specific medication can be avoided or postponed in these patients due to the rapid response to IV FCM treatment.     

Family history study of the restless legs syndrome

Background: Although there is a relatively high rate of occurrence of sporadic cases of restless legs syndrome (RLS), the systematic study of family history of RLS in populations of RLS patients has been very limited. The objective of the present study was to determine the risk of RLS for first- and second-degree relatives of a population of primary RLS patients not selected for the number of affected relatives in their families and to obtain an estimate of the degree of genetic involvement in RLS.Methods: Consecutively consenting patients from two different sites who met the criteria for RLS completed a worksheet that asked them to indicate their current age, the date of their earliest RLS symptoms, and the names and RLS status of all of their first- and second-degree relatives. Controls with no clinical history of RLS also completed the worksheet.Results: First- and second-degree relatives of patients with RLS had a significantly greater risk of RLS than the first- (P<0.001) and second-degree relatives (P<0.003) of controls. The risk of RLS was found to be greater for first-degree relatives of early-onset, rather than late-onset, RLS probands (P<0.001).Conclusions: This study provides a complete systematic examination of the risk of RLS among relatives of RLS probands and controls using the same assessment methodology. Although the results are consistent with a genetic etiology for RLS, they do not support the presence of one simple, Mendelian-inherited major gene in most RLS families.     

普拉克索治疗原发性不宁腿综合征的疗效和安全陛观察

目的 观察普拉克索对我国原发性不宁腿综合征(RLS)患者的治疗效果以及可能发生的不良反应. 方法 选择自2009年5月至11月在哈尔滨医科大学第二附属医院神经内科就诊的10例中到重度原发性RLS患者,给予普拉克索0.125～0.75mg/d,每日睡前2～3h顿服,持续治疗6周.利用国际RLS研究小组的RLS严重程度量表(mLS)、临床总体印象改善量表(CGI-I)、患者总体印象量表(PGI)和Epworth嗜睡量表(ESS)对患者治疗前后的RLS症状严重程度和嗜睡程度进行评估.并对结果进行统计学分析,同时记录不良反应.结果 (1)治疗后患者的IRLS评分较治疗前平均降低73.7%,比较差异有统计学意义(P<0.05),9例患者IRLS评分降低在50%以上;(2)治疗结束时,8例患者PGI评估选择很好或非常好,9例患者CGI-I评估为明显改善或非常明显改善;(3)患者ESS评分在治疗后较治疗前平均降低3.80±1.75,比较差异有统计学意义(P<0.05);(4)1例患者在治疗末期加量至0.5mg/d时出现轻度恶心,胃区不适,治疗结束停药2 d后症状自行消失;(5)1例患者首次用药后双下肢感觉异常和睡眠障碍即有明显改善.结论 为期6周的临床实验表明,在每日口服剂量为0.125～0.75 mg时,普拉克索对于我国原发性RLS的治疗是安全有效的.     

A 52-week open-label study of the long-term safety of ropinirole in patients with restless legs syndrome

OBJECTIVE: To assess the long-term safety and efficacy of ropinirole in the treatment of patients with restless legs syndrome (RLS) over 52 weeks. METHODS: A 52-week, multicentre, open-label continuation study involving 310 patients, conducted in 11 countries. Eligible patients from four parent studies were invited to participate. At parent study entry, all patients had a score of > or =15 on the International Restless Legs Scale (IRLS). In this continuation study, all participants received ropinirole, 0.25-4.0 mg once daily, for 52 weeks. The primary study objective was to evaluate the safety of ropinirole. Efficacy was assessed by change in IRLS score, as well as by global improvements (clinical global impression [CGI] scale) and improvements in measures of sleep, work productivity, and quality of life. RESULTS: Overall, 251 (81.0%) patients completed the study. The mean ropinirole dose at study end was 1.90 mg/day. A total of 282 patients (91.3%) reported > or = 1 adverse event. For the majority of patients, the reported adverse events were mild or moderate in intensity. The most common adverse event was nausea. Adverse events led to discontinuation in 8.7% of patients. At week 52, IRLS scores improved by an average of 12.0 points from baseline, and 82.8% of patients were 'much improved' or 'very much improved' on the CGI-improvement scale. Ropinirole treatment was also associated with improvements in measures of sleep and quality of life. CONCLUSIONS: Ropinirole was well tolerated and therapeutic efficacy was maintained over 52 weeks in patients with RLS.     

An item response analysis of the international restless legs syndrome study group rating scale for restless legs syndrome

BACKGROUND AND PURPOSE: Restless legs syndrome (RLS) is a common central nervous system disorder; however, there is currently a lack of well-validated and easily-administered measures of RLS severity available. The International Restless Legs Syndrome Study Group has recently developed a 10-item scale to meet this need. The International Restless Legs Severity Scale (IRLS) has been shown to have a high degree of reliability, validity, and internal consistency. In order to further demonstrate the validity of the IRLS, the present study examined the relationship between scores on individual IRLS items and overall RLS severity. PATIENTS AND METHODS: The 10-item IRLS was administered to 196 RLS patients. Option characteristic curves (the probability of scoring different options for a given item as a function of overall IRLS score) were generated in order to illustrate the scoring patterns for each item across the range of total RLS severity. Item characteristic curves (the expected score on an item as a function of overall IRLS score) were also generated to illustrate the relationship between scores on the individual items and total RLS severity. RESULTS: The IRLS items demonstrated excellent item response properties, with option and item characteristic curves closely approximating those of an ideal item. Item 3 (relief of arm or leg discomfort from moving around) was the most problematic item in that a 'floor' effect was evident; however, the item response characteristics for this item were still acceptable. CONCLUSIONS: Each IRLS item showed a good relationship between responses on that item and overall RLS severity, providing further evidence for the validity of the IRLS as a measure of RLS severity in RLS patients.