title: Restless legs syndrome status as a predictor for lower physical function.
abstract: OBJECTIVE
  To examine the potential long-term impact of restless legs syndrome (RLS) and other common sleep complaints on subsequent physical function (PF), we conducted a longitudinal analysis of 12,556 men in the Health Professionals Follow-up Study.
  
  
  METHODS
  We used a set of questions recommended by the International RLS Study Group to assess RLS in 2002. We asked questions regarding other sleep complaints--insomnia, sleep fragmentation, and excessive daytime sleepiness--in 2004. We used the Physical Function (PF-10) survey of the Short Form-36 Health Survey to characterize PF in 1996 and 2008. We examined the 2008 PF-10 scores across categories of baseline RLS (2002), adjusted for age, 1996 PF-10 score, and other potential confounders.
  
  
  RESULTS
  The participants with RLS at baseline had significantly lower PF-10 score 6 years later than those without RLS (mean difference = -2.32, p = 0.01), after adjusting for potential confounders. The magnitude of difference in PF-10 score for RLS symptoms ≥ 15 times/month vs no RLS was more than that of a 5-year increase of age or moderate amount of smoking. Having daily daytime sleepiness and sleep duration ≥ 9 hours/day were associated with lower mean PF value than not having these symptoms (p < 0.05 for both).
  
  
  CONCLUSIONS
  RLS and other sleep complaints are associated with lower PF. Our findings need to be replicated by more longitudinal studies including women and populations of other social and cultural backgrounds. It is important to understand whether RLS is an independent risk factor or a marker for other unknown risk factors for disability.
authors.affiliation: From The Channing Division of Network Medicine (C.Z., Y.L., X.G.) and Division of Sleep Medicine (C.Z., A.M.), Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; the Department of Epidemiology and Community Health (Y.N.), Virginia Commonwealth University, Richmond; the Department of Nutrition (X.G.), Harvard School of Public Health, Boston, MA; and School of Public Health (XG), Peking Union Medical College, Beijing, China.
authors.forename: Chunbai
authors.initials: C
authors.lastname: Zhang
authors.forename: Yanping
authors.initials: Y
authors.lastname: Li
authors.forename: Atul
authors.initials: A
authors.lastname: Malhotra
authors.forename: Yi
authors.initials: Y
authors.lastname: Ning
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
mesh_terms: D000328:Adult; D000368:Aged; D005500:Follow-Up Studies; D006306:Health Surveys / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012148:Restless Legs Syndrome / Q000150:complications / Q000503:physiopathology*; D012307:Risk Factors; D012890:Sleep; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications / Q000503:physiopathology*; D011795:Surveys and Questionnaires