Sleep Medicine
Volume 10, Issue 9 , Pages 976-981, October 2009

The four diagnostic criteria for Restless Legs Syndrome are unable to exclude confounding conditions (“mimics”)

  • Wayne A. Hening

      Affiliations

    • UMDNJ-RW Johnson Medical Center, New Brunswick, NJ, USA
    • ,
  • Richard P. Allen

      Affiliations

    • Johns Hopkins University, Baltimore, MD, USA
    • Corresponding Author InformationCorresponding author. Address: Asthma and Allergy, Rm 1B75B, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA. Tel.: +1 410 550 2609; fax: +1 410 550 3364.
    • ,
  • Mystinna Washburn

      Affiliations

    • Johns Hopkins University, Baltimore, MD, USA
    • ,
  • Suzanne R. Lesage

      Affiliations

    • University of Maryland Medical Center, Baltimore, MD, USA
    • ,
  • Christopher J. Earley

      Affiliations

    • Johns Hopkins University, Baltimore, MD, USA

Received 2 March 2008; received in revised form 18 September 2008; accepted 22 September 2008.

Abstract 

Background

Epidemiological survey studies have suggested that a large fraction of the adult population, from five to more than 10%, have symptoms of Restless Legs Syndrome (RLS). Recently, however, it has become clear that the positive predictive value of many questionnaire screens for RLS may be fairly low and that many individuals who are identified by these screens have other conditions that can “mimic” the features of RLS by satisfying the four diagnostic criteria. We noted the presence of such confounders in a case-control family study and sought to develop methods to differentiate them from true RLS.

Methods

Family members from the case-control study were interviewed blindly by an RLS expert using the validated Hopkins telephone diagnostic interview (HTDI). Besides questions on the four key diagnostic features of RLS, the HTDI contains open-ended questions on symptom quality and relief strategies and other questions to probe the character of provocative situations and modes of relief. Based on the entire HDTI, a diagnosis of definite, probable or possible RLS or Not-RLS was made.

Results

Out of 1255 family members contacted, we diagnosed 1232: 402 (32.0%) had definite or probable RLS, 42 (3.3%) possible RLS, and 788 (62.8%) Not-RLS. Of the 788 family members who were determined not to have RLS, 126 could satisfy all four diagnostic criteria (16%). This finding indicates that the specificity of the four criteria was only 84%. Those with mimic conditions were found to have atypical presentations whose features could be used to assist in final diagnosis.

Conclusion

A variety of conditions, including cramps, positional discomfort, and local leg pathology can satisfy all four diagnostic criteria for RLS and thereby “mimic” RLS by satisfying the four diagnostic criteria. Definitive diagnosis of RLS, therefore, requires exclusion of these other conditions, which may be more common in the population than true RLS. Short of an extended clinical interview and workup, certain features of presentation help differentiate mimics from true RLS.

Keywords: Restless legs, Diagnosis, Differential diagnosis, Specificity, Positive predictive value, Validation, Family study

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PII: S1389-9457(08)00361-4

doi:10.1016/j.sleep.2008.09.015

Sleep Medicine
Volume 10, Issue 9 , Pages 976-981, October 2009

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