High false-positive rate of questionnaire-based restless legs syndrome diagnosis in multiple sclerosis

Sleep Med. 2015 Jul;16(7):877-82. doi: 10.1016/j.sleep.2015.02.529. Epub 2015 Mar 6.

Abstract

Background/objectives: Restless legs syndrome (RLS) is diagnosed by self-reported symptoms. Multiple sclerosis (MS) patients have disease-related symptoms which could mimic RLS. This study assessed the: (1) false-positive rate for questionnaire-based RLS diagnosis in MS patients and (2) utility of periodic leg movements during wakefulness (PLMW) on overnight polysomnography (PSG) in identifying true-positive RLS patients.

Methods: Ambulatory MS patients without known sleep disorders were recruited. Subjects completed the International RLS Study Group (IRLSG) diagnostic questionnaire (IRLDQ) and underwent full overnight PSG. IRLDQ-positive patients underwent clinical evaluation to confirm the diagnosis and completed the RLS severity scale (IRLS).

Results: Seventy-one MS patients (mean age 46.8 ± 10.4 years) were evaluated. Thirty-eight had a positive IRLDQ. RLS diagnosis was confirmed in 22, yielding a false-positive rate of 42% [95% confidence interval (CI) 26-59%], predominantly attributable to paresthesiae (n = 7), and cramps and/or muscle spasms (n = 4). IRLS scores were not significantly different between subjects with confirmed and nonconfirmed RLS. The PLMW index was significantly higher in patients with confirmed RLS (55.4 ± 41.9 vs. 29.7 ± 18.8, p = 0.03). The sensitivity of a PLMW index >70/h for true-positive IRLDQ was 8/22 = 36%, 95% CI: 17.2-59.3, and the specificity was 16/16 = 100%, 95% CI: 79.4-100.

Conclusions: MS patients have a high false-positive rate of RLS diagnosis using a standardized questionnaire largely attributable to MS-related sensorimotor symptoms. While detailed clinical evaluation is essential for confirming RLS diagnosis, the PLMW index may provide useful adjunctive information.

Keywords: International Restless Legs Syndrome Study Group questionnaire; Multiple sclerosis; Periodic leg movements; Polysomnography; Restless legs syndrome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cross-Sectional Studies
  • Diagnosis, Differential
  • Disability Evaluation
  • False Positive Reactions
  • Female
  • Humans
  • Male
  • Middle Aged
  • Multiple Sclerosis / diagnosis*
  • Polysomnography
  • Psychometrics / statistics & numerical data
  • Restless Legs Syndrome / diagnosis*
  • Surveys and Questionnaires*