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Clinical bottom line

The prevalence of RLS in end-stage renal disease is of the order of 20-40%.

Reference

GL Gigli et al. Restless legs syndrome in end-stage renal disease. Sleep Medicine 2004 5: 309-315.

Study

All patients undergoing haemodialysis in a region of Italy were given a questionnaire about restless legs symptoms, including current diagnostic criteria. Part was completed by the patient, while a second part completed by the physician included questions about medical history and treatment. Data from 601 consecutive questionnaires are given.

Results

The average age of patients was 64 years, and 82% were over 45 years. Positive responses to all four diagnostic questions were given by 22% of patients.

Patients with RLS tended to have been on dialysis longer, and be less likely to be using phosphorus binders and antihypertensive medicines. They also had significantly more sleep problems and daytime somnolence than dialysis patients without RLS.

Review of RLS prevalence in end-stage renal disease

Also contained in the paper, but without a systematic search, was information on other studies examining RLS prevalence in end-stage renal disease. Most of these used current diagnostic criteria, and reported prevalence ranging from 7% to 83%. Most large studies reported prevalence in the range of 20-40%.

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Clinical bottom line

The prevalence of RLS in patients on maintenance haemodialysis is 14%. Patients with RLS had significantly poorer sleep and quality of life.

Reference

I Musci et al. Restless legs syndrome, insomnia and quality of life in patients on maintenance dialysis. Nephrology Dialysis Transplantation 2005 20: 571-577.

Study

This was a population based study on patients on maintenance haemodialysis and on dialysis awaiting transplant in Budapest. All patients were asked to complete a battery of tests relating to restless legs, sleep, and quality of life. Demographic information was also collected.

Results

The final study population was 333 individuals, with an average age of 54 years. About half were men, and 22% had diabetes. The median time on dialysis was 34 months.

The prevalence of RLS was 14% (45/333). There was no difference between those with and without RLS in duration of haemodialysis, age or sex, diabetes, or serum albumin, ferritin, or phosphorus. Prevalence increased from about 8% in those with no comorbid conditions to about 22% in those with five or more comorbid conditions.

Patients with RLS had much worse sleep than those without RLS, both in distribution of sleep scores, and in specific symptoms like sleep initiation or daytime tiredness. Quality of life measures also tended to be worse in patients on haemodialysis with RLS.

Comment

The prevalence of RLS in patients on maintenance haemodialysis is 14%. Patients with RLS had significantly poorer sleep and quality of life.

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All people with RLS should have their ferritin levels tested; ferritin levels should be at least 50 mcg for those with RLS. Oral iron supplements, taken under a doctor’s care, can increase ferritin levels. For some people, increasing ferritin will eliminate or reduce RLS symptoms. A ferritin level of 50 mcg is not sufficient for some sufferers and increasing the level to 80 mcg may greatly reduce symptoms. However, at least 40% of people will not notice any improvement. Treatment with IV iron is being tested at the US Mayo Clinic and John Hopkins Hospital. It is dangerous to take iron supplements without first having ferritin levels tested, as many people with RLS do not have low ferritin and taking iron when it is not called for can cause hemochromatosis, a very dangerous condition.

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• Restless leg syndrome is a condition marked by unpleasant leg sensations at bedtime.
• Restless leg syndrome frequency leads to insomnia.
• The cause of restless leg syndrome is unknown in most patients, but many conditions have been associated with it.
• Treatment of restless leg syndrome is directed toward any underlying illness, if known.
• Medications are available for restless leg syndrome.

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RLS after renal transplant

Clinical bottom line

RLS prevalence after renal transplant is high (24%) in patients with glomerular filtration rate below 15 mL/min.

Reference

MZ Molnar et al. Restless legs syndrome in patients after renal transplantation. American Journal of Kidney Diseases 2004 45: 388-396.

Study

This was a population-based study of all patients at a single transplant unit in Budapest who had received a cadaveric transplant. They were asked to participate in a study of sleep disorders and health-related quality of life. Demographic details were collected, and questionnaires completed on symptoms like insomnia and sleep, restless legs, and quality of life.

Results

Of 1,067 transplant patients, 816 agreed to participate and completely filled the questionnaires.

The prevalence of RLS was 4.8%. There was no difference between patients with and without RLS with regard to age sex, BMI, education, or any other demographic variable. Patients with RLS tended to have more self-reported co-morbidity (3 versus 2 conditions).

RLS prevalence was significantly higher in transplant patients with poor renal function, whose glomerular filtration rate (GFR) was below 15 mL/min. There was no significant difference in RLS with Hb values.

Comment

RLS prevalence after renal transplant is high (24%) in patients with glomerular filtration rate below 15 mL/min.

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RLS in primary care

Clinical bottom line

About 1 in 30-50 adults has RLS symptoms sufficiently severe to be worthy of treatment. Of these, only a quarter have been diagnosed, and fewer treated.

Reference

W Hening et al. Impact, diagnosis and treatment of restless legs syndrome (RLS) in a primary care population: The REST (RLS epidemiology, symptoms, and treatment) primary care study. Sleep Medicine 2004 5: 237-246.

Study

The study was conducted in the USA, France, Germany, Spain and Uk. Primary care practices in all countries (182) had 23,052 patients. Primary care physicians participating were not told that it was a study of RLS.

In the study, patients who visited for any reason over a two week enrolment period were asked to complete a screening questionnaire. A presumptive diagnosis of RLS required a positive response to four diagnostic criteria. Those with a presumptive diagnosis and whop reported RLS at least once a week were asked to complete a more detailed questionnaire, including information on demographics, lifestyle, symptoms, and diagnostic and treatment history. Doctors also filled a separate questionnaire for these patients.

Results

The prevalence of any degree of RLS was 11%, and for symptoms occurring at least once a week was 10%, twice a week 5%, and 2.4% in those with a significant negative impact on quality of life (defined as sufferers and likely to require treatment). The variation between countries was large, with 1.9% of sufferers in Spain to 5.8% in the USA and 5.6% in the UK.

Sufferers had an average age of 57 years, with two-thirds women, with a mean duration of symptoms of 10-12 years. About two-thirds of sufferers had consulted a GP about their symptoms in the previous 12 months, with about a quarter receiving a diagnosis of RLS. Most had other conditions, and back pain, depression, hypertension, insomnia, anxiety, arthritis, obesity and cardiovascular conditions were common, whether defined by patient or doctor.

Symptoms most frequently reported are shown in Table 1, with sleep-related symptoms, uncomfortable feelings in legs, and pain the most common symptoms.

Table 1: Commonly reported symptoms by RLS sufferers

RLS sufferers reported considerable difficulty in getting off to sleep. Only 30% were asleep within 30 minutes, with 34% taking more than an hour, and 15% more than two hours. Almost two-thirds of sufferers were woken during the night by their restless legs three times or more.

The study also describes the number of different consultations with specialists the sufferers had had, and any medications prescribed for it. Patients in France saw a specialist most often (70% of them), whilst those from the UK saw a specialist least often (fewer than 50%). There was no simple or consistent pattern to prescribing, but those with a diagnosis of RLS were more likely to be prescribed L-dopa.

Comment

This is a large study, well conducted. The estimate of 10% of adults having RLS symptoms at least once a week is possibly a bit high because it sampled people visiting their primary care physician, though it is in general agreement with other estimates. Perhaps as few as 1 in 30-50 has symptoms sufficiently severe to be worthy of treatment. Of these, only a quarter have been diagnosed, and fewer treated.

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Oxycodone for RLS

Clinical bottom line

A single small trial provides insufficient evidence to draw any conclusions.

Reference

AS Walters et al. Successful treatment of the idiopathic restless legs syndrome in a randomized double blind trial of oxycodone versus placebo. Sleep 1993 16: 327-332.

Clinical trial

This trial was randomised and double blind, and studies 11 patients. The crossover design tested oxycodone titrated to a maximum of 25 mg daily against placebo over two weeks per treatment. Outcomes were subjective assessments of motor restlessness, leg sensations, and drowsiness. Sleep studies were also carried out as the main purpose of the trial.

Results

The mean age of patients was 55 years (range 41-74). Subjective outcomes were all statistically improved on oxycodone. Periodic limb movements while sleeping, sleep arousals, and sleep efficacy were all improved on oxycodone. Adverse events were few and mild, but included constipation and lethargy at higher doses of oxycodone.

Comment

There is insufficient evidence to conclusively comment on efficacy or safety of oxycodone for RLS.

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Clinical bottom line

The prevalence of RLS in children attending a sleep disorders programme was 5.9% (definite 4.2%; probable 1.7%).

Reference

S Kotagal, MH Silber. Childhood-onset restless legs syndrome. Annals of Neurology 2004 56: 803-807.

Study

The setting was 538 patients aged 18 or under attending a sleep disorders programme over four years at the Mayo clinic. Current diagnostic criteria for RLS in children were used.

Results

Out of 538 children, 23 fulfilled criteria for definite RLS, and nine criteria for probable RLS. Sleep onset or insomnia problems were the most common presenting complaint, in 9/9 in the probable and 19/23 of definite diagnoses of RLS.

The 32 children with definite or probable RLS according to the new diagnostic criteria contrasted with 62 with RLS before the criteria were applied.

Comment

RLS can occur in children, but was uncommon even in children attending a sleep disorders clinic.

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An urge to move, usually due to uncomfortable sensations that occur primarily in the legs.”The sensations are unusual and unlike other common sensations, and those with RLS have a hard time describing them. People use words such as: uncomfortable, antsy, electrical, creeping, painful, itching, pins and needles, pulling, creepy-crawly, ants inside the legs, and many others. The sensation and the urge can occur in any body part; the most cited location is legs, followed by arms. Some people have little or no sensation, yet still have a strong urge to move.

• “Motor restlessness, expressed as activity, that relieves the urge to move.”

Movement will usually bring immediate relief, however, often only temporary and partial. Walking is most common; however, doing stretches, yoga, biking, or other physical activity may relieve the symptoms. Constant and fast up-and-down movement of the leg, coined “sewing machine legs” by at least one RLS sufferer, is often done to keep the sensations at bay without having to walk. Sometimes a specific type of movement will help a person more than another.

• “Worsening of symptoms by relaxation.”

Any type of inactivity involving sitting or lying – reading a book, a plane ride, watching TV or a movie, taking a nap - can trigger the sensations and urge to move. This depends on several factors: the severity of the person’s RLS, the degree of restfulness, the duration of the inactivity, etc.

• “Variability over the course of the day-night cycle, with symptoms worse in the evening and early in the night.”

While some only experience RLS at bedtime and others experience it throughout the day and night, most sufferers experience the worst symptoms in the evening and the least in the morning.

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