Restless Legs Syndrome Morbidity: Sleep and Quality of Life

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Chapter 37 Restless Legs Syndrome Morbidity: Sleep and Quality of Life

Aside from the increased risk of death for patients with both restless legs syndrome (RLS) and end-stage renal disease (see Chapter 25), RLS has no known impact on mortality. But the symptoms associated with the disorder adversely affect several key aspects of daily life. We often assume that we already know the impact of these symptoms on functioning and therefore focus mostly on describing and evaluating the symptoms rather than looking at their impact on the patient’s life. Indeed, this approach has been taken for RLS, and even as late as 2003 there had been very few published studies on the morbidity of RLS. This turns out to be particularly regrettable for RLS. For the morbidity may provide an important, if not the primary, justification for treatment of the disorder. The rationale for treatment then lies not merely with reducing the symptoms but also with reducing the impact they have on the patient’s life.

Two broad areas of RLS morbidity have been identified: sleep disturbance and impact on quality of life (QoL). The sleep disturbance has been characterized for RLS, but only a few studies have addressed the impact this has on the patient. Similarly, only limited attention has been paid to the QoL of the RLS patient. To study this morbidity of RLS, we need to more directly evaluate the health-related QoL. Results from such studies of sleep and QoL could both justify treatment and provide some general guidelines regarding severity levels appropriate for treatment and areas of focus for treatments. Moreover, the nature of the impact of RLS on sleep and QoL may provide information about the clinical features of RLS. We may assume that we know the clinical significance of the disorders we treat, but the nature of their impact may be surprising. A broad-based evaluation of sleep-related and health-related QoL may reveal overlooked clinical features of RLS and may even suggest endophenotypic differences within the general RLS population. Thus, focusing on the impact of RLS serves to evaluate both the expression of the disorder and its significance.

Morbidity From Sleep Disturbance of Restless Legs Syndrome

RLS classification as a sleep-related disorder1 emphasizes the sleep disturbance characterizing the disorder. By definition, rest provokes RLS symptoms and it can be seen as a disorder of that quiet drowsy state of waking (the predormitum) that precedes sleep but may occur at other times during the day. RLS will therefore generally disrupt sleep, and indeed, the population-based surveys indicate more than 75% of those with at least moderate RLS symptoms complain of significant sleep disturbance caused by their RLS.2 It appears that some who have very mild RLS do not have any sleep complaint. In such cases, the patient appears to fall asleep fast enough to avoid developing significant symptoms while lying in bed; the longer periods of sitting in the evening, however, cause considerable distress. Most RLS patients, though, complain of interrupted sleep, insufficient hours of sleep, and difficulty falling and staying asleep. Curiously, only a minority complain of daytime sleepiness.2 Figure 37-1 shows the range of RLS effects on sleep onset and sleep awakenings for those with moderate to severe RLS symptoms. These have been confirmed by polysomnographic studies of RLS patients3 and by reports from clinical trial populations showing decreased total sleep times, decreased sleep adequacy, and increased sleep disturbance, which are largely improved by treatment with the dopamine agonist ropinirole.4,5 Sleep efficiency for the more severely affected RLS patient drops below 60% with less than 5 hours a sleep a night for most nights,6 producing what is probably the most extreme chronic sleep loss of any sleep-related disorder; yet, there have been few studies evaluating the effect of this sleep loss.


FIGURE 37-1. Restless legs syndrome (RLS)-related sleep complaints of those with moderate to severe RLS symptoms in a large primary care population survey. (A) Reported RLS-related sleep-onset times. (B) Reported RLS-related number of awakenings on usual nights.

From Hening W, Walters AS, Allen RP, 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 Med 2004;5:237-246.

Profound daytime sleepiness should develop with this level of sleep loss, but surprisingly RLS patients generally do not report falling asleep in the daytime at inappropriate times (e.g., sitting in a car at a red light, talking on the telephone). Thus, the question arises—Aside from the discomfort from not sleeping, do RLS patients have any adverse effects from the sleep loss? That is, do RLS patients show changes in mood, cognition, attention, or pain perception generally associated with significant sleep loss? Unfortunately, to date, this has hardly been studied at all. Saletu and colleagues7 found no excessive sleepiness or vigilance decrement for untreated RLS patients compared with control subjects. Pearson and colleagues,8 however, did find that untreated RLS patients had decreased cognitive performance in the morning on verbal fluency and trail making tests consistent with the prefrontal cognitive effects shown for one night’s of total sleep deprivation.9 Aside from these studies, we know very little about the effects of the sleep disturbance in RLS. It looks as if it produces an awake, but possibly fatigued, individual with some disturbance of prefrontal cognitive functioning, a type of dysfunction also shown with attention deficit disorder.10

Quality of Life Measures Used in Restless Legs Syndrome

Three basic types of QoL measurements have been developed: general QoL assessments, disease-specific QoL measures, and judgments or recording of critical life-activities or events. The general QoL assessments usually focus on providing a broad-based assessment of health-related impacts on QoL. Several instruments have been developed to provide this type of QoL assessment, including the Nottingham Health Profile, the Sickness Impact Profile, and the 36-item Short-form Health Survey (SF-36). The most commonly used and best standardized is the Medical Outcomes Study11 SF-36,12,13 which has been shown to have very good psychometric properties when used in a patient population.14 The SF-36 also comes in two shortened forms: the SF-1215 and the SF-8.16 The SF-36 provides scores in eight dimensions and a summary score for four dimensions covering physical health (physical functioning, role physical, pain, and general health) and four covering mental health (role emotional, vitality, social functioning, and mental health).

The generic QoL allow quantitative comparisons with a normative population and between differing disorders. Thus, they provide a rationale for treatment and a possible metric for measuring its success. Unfortunately, the strength of the broad-based approach of these instruments also represents their major weakness. Many factors affect these scales so that when looking for treatment effects the change from treatment is obscured by changes or lack of other factors affecting QoL. Moreover, some of the QoL issues may be more specific to a particular disorder and as such need to be more directly addressed than occurs in a generic QoL. A disease-specific QoL can incorporate both dimensions of particular significance for a particular disorder and those that are expected to modulate with treatment of the disorder. Another targeted approach, the use of measures of life events or choices can focus on evaluating select and relevant behaviors or judgments about behaviors. This approach includes records such as work attendance or an inventory of patient judgments or choices about life events. They produce an interesting range of alternate QoL measures but have yet to become established as a standard approach.

RLS has now been evaluated using both the generic and disease-specific QoL. Both of these approaches focus on the adverse impact of health problems on daily functioning over the most recent 4 weeks. The generic QoL involve some generic health issues such as “bodily pain.” The RLS patient’s responses depend largely on how he or she relates the symptoms to these generic type descriptors. The disease-specific QoL instruments are not dependent on such a relation. Both measures focus on deficits and have a ceiling effect that could make it difficult to see enhancements to life that might occur with treatments, but the QoL model in this work focuses on evaluating the degree of disease related impairment and the improvements toward normal and not enrichment of daily life.