Special Section in Sleep MedicineRestless legs syndrome/Willis–Ekbom disease diagnostic criteria: updated International Restless Legs Syndrome Study Group (IRLSSG) consensus criteria – history, rationale, description, and significance
Introduction
Restless legs syndrome (RLS), also known as Willis–Ekbom disease (WED), is a common neurological, sensorimotor disorder. In European and American populations, about 2–3% of adults suffer from clinically significant symptoms [1]. Clinically significant RLS/WED has a substantial negative impact on sleep, quality of life, and health [1], [2], [3]. Following a 2003 workshop at the National Institutes of Health (NIH), the International Restless Legs Syndrome Study Group (IRLSSG) developed updated diagnostic criteria that have enabled rapid development of research and treatments for RLS/WED over the past decade [4]. The accumulating research and clinical experience, however, have led to a broad-based consensus for a need to enhance the diagnostic criteria, primarily adding additional elements to improve specificity without changing the fundamental features of RLS/WED diagnosis. In 2012, the IRLSSG revised the 2003 NIH/IRLSSG criteria for RLS/WED [4], [5], which are presented here and on the IRLSSG web site (IRLSSG.org).
This 2012 revision of the 2003 NIH/IRLSSG criteria raises two fundamental questions: Why revise them now and how does the revision impact our field, especially for research? By presenting the history, rationale, and significance of the revised criteria, this article addresses these fundamental questions. Furthermore, this article describes in detail the five essential features of the 2012 revised diagnostic criteria and other supportive and associated features of RLS/WED that can aid clinicians and researchers alike in the overall diagnostic assessment. For special populations (i.e. children and cognitively impaired elderly), where the sensory features of RLS/WED may be hard to determine or are unreliable, specific suggestions are discussed. Finally, a consideration of the significance of the revised criteria introduces potential venues for improving our research methods in clinical studies and epidemiology.
It is important to underscore that the 2012 IRLSSG revised criteria represent the only diagnostic criteria developed by a consensus process involving a large international body of RLS/WED clinical and research experts. Through an interdisciplinary, international and evidence-based approach, the IRLSSG sought to avoid three problems. First, the strong interdisciplinary nature of RLS/WED experts reduces the possibility that the diagnostic criteria will be subtly distorted to fit within a framework developed for any one particular discipline. Second, the diversity and global nature of the IRLSSG reduces the risk of cultural bias that might limit the generalizability across racial and ethnic groups. Third, the evidence-based, conservative approach avoids arbitrary and negative impact on validity or significance of prior RLS/WED studies.
Section snippets
History of RLS/WED diagnostic criteria
Table 1 presents the new, updated IRLSSG diagnostic criteria for RLS/WED and Table 2 presents the historic development of these criteria.
Although RLS/WED was first described by Thomas Willis in 1685 [6], the formal diagnostic criteria start with the seminal monograph “Restless Legs” by Karl-Axel Ekbom in 1945 [7]. He offered the following diagnostic guidance in 1960:
“The following criteria should be borne in mind. The sensations appear only when the patient is at rest, most often in the evening
Rationale for revision of the 2003 NIH/IRLSSG criteria
The 2003 NIH/IRLSSG criteria contributed to several milestones in the field of RLS/WED research. First, the workshop’s recommendation for a simple three-item questionnaire based on the 2003 NIH/IRLSSG criteria led to epidemiological studies revealing that 7–10% of the general adult population in Europe and the USA have symptoms meeting the RLS/WED diagnostic criteria, and 2–3% of the total population (20–40% of all reporting RLS/WED symptoms) have significant suffering associated with their
Process for revising the diagnostic criteria
In recognition of the developing need to revise the diagnostic standards for RLS/WED, the IRLSSG and WED Foundation sponsored a one-day clinical standards workshop (chair: Richard Allen) on October 26th, 2008, at the Johns Hopkins Mount Washington Conference Center, Baltimore, MD, USA. Members of the IRLSSG were invited to update and revise the 2003 diagnostic criteria for RLS/WED. To address specific aspects of the 2003 criteria the attendees were assigned to three different workgroups based
IRLSSG consensus diagnostic criteria
RLS/WED, a neurological sensorimotor disease … is diagnosed by ascertaining symptom patterns that meet the following five essential criteria adding clinical specifiers where appropriate.
RLS/WED arises from dysfunction of the central nervous system that leads to both sensory and motor symptoms. No biological assay is available to make a diagnosis of RLS/WED. Clinical diagnosis of RLS/WED is based on clinician interaction with the patient and assessment by the clinician of the patient’s
Features supporting the diagnosis of RLS/WED
RLS/WED has both a motor sign and several common clinical patterns that can support a diagnosis, particularly when there is some lack of diagnostic certainty (Table 4).
Features to be considered for a comprehensive diagnostic assessment of RLS/WED
The clinical features presented in Table 5 are particularly important for completing a full diagnostic assessment of RLS/WED status. These features may also impact treatment options. Some are common to other conditions, but, as explained below, they all have particular significance for RLS/WED.
Pediatric diagnostic criteria
The 2003 NIH/IRLSSG criteria included separate criteria for children and defined definite, probable, and possible pediatric RLS/WED [4]. Based on new research, the pediatric RLS/WED diagnostic criteria have been simplified and integrated with the newly revised adult RLS/WED criteria. Table 1, footnote b of the new criteria emphasizes the importance of symptom description in the child’s own words for criterion 1, and footnote f indicates that the clinical course criteria do not apply for
Diagnosis for cognitively impaired seniors
The 2003 NIH/IRLSSG diagnostic criteria included separate consideration for the cognitively impaired elderly. Some ongoing studies have sought behavioral observations that might be used to identify RLS/WED in this population but none of these have yet published satisfactory results. Cognitive and communication problems distort the description of core RLS/WED symptoms. The situation is further complicated by the large increase in PLMS and PLMW at night with age [125] and the difficulty of even
Comparison to the diagnostic and statistical manual of mental disorders, fifth edition (DSM-5) and the international classification of sleep disorders, third edition (ICSD-3) diagnostic criteria for RLS/WED
Previously, RLS/WED was not listed in DSM-IV and was subsumed under the diagnostic category of Dyssomnia Not Otherwise Specified. However, in the recently released fifth edition of DSM, RLS/WED is elevated to a separate diagnostic entity based on the public health significance of the condition, scientific progress made by RLS/WED researchers, and on the necessity of defining a clinically significant condition that is commonly encountered in daily psychiatric practice [172]. There are several
Significance of the new diagnostic criteria and specifiers
The new diagnostic criteria address two important areas for RLS/WED clinicians and researchers: a more rigorous approach to RLS/WED case ascertainment to achieve improved validity and better characterization of clinical and research samples by specifying clinical course and clinical significance.
Ensuring attention to the differential diagnosis required by the new fifth criterion encourages development of standardized and validated methods for improved case ascertainment. This is particularly
Conclusions and future directions
The revised diagnostic criteria aim to contribute to the field by improving diagnostic validity and case ascertainment and by facilitating clear communication among RLS/WED clinicians and researchers. The current revision of diagnostic criteria was undertaken with respect and appreciation for the earlier work by the pioneers in the field of RLS/WED and aims to avoid arbitrary alteration of current clinical practice and research without available supporting empirical evidence. The newly revised
Funding sources
None.
Conflict of interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2014.03.025.
Acknowledgments
Contributors to these consensus diagnostic criteria included the following, who attended the IRLSSG clinical workshop in 2008 or who contributed after that via meetings, telephone conversations, or online discussion.
Charles H. Adler, Mayo Clinic, Scottsdale, AZ; Richard P. Allen, Johns Hopkins University, Baltimore, MD, USA; Flávio Aloe, Universidade de São Paulo (USP), São Paulo, Brazil; Cornelius Bachmann, Georg August University, Goettingen, Germany; Philip Becker, Sleep Medicine Associates
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