title: Periodic limb movement during sleep is associated with nocturnal hypertension in children.
abstract: BACKGROUND
  Increasing evidence suggests that blood pressure (BP) is significantly influenced by sleep problems in children, but the association between periodic limb movement during sleep (PLMS) and BP is still unclear. This study aims to compare ambulatory blood pressure (ABP) in children with and without PLMS.
  
  
  RESULTS
  A cross-sectional study involving 314 children (mean (SD) age of 10.4 (1.7) years, boys 62.4%). Participants underwent an overnight polysomnographic study and ABP monitoring. Subjects were hypertensive if mean SBP or DBP > 95th percentile and prehypertensive if mean SBP or DBP > 90th percentile of reference. Children with PLMS (n = 17) were at significantly higher risk for nocturnal systolic (adjusted OR (95%CI) = 6.25 [1.87-20.88]) and diastolic (OR (95%CI) = 4.83 [1.66-14.07]) hypertension. However, mean nocturnal BP did not differ between children with and without PLMS. There was a trend for higher daytime BP in patients with PLMS than those children without PLMS (P = 0.084 for systolic BP z score; P = 0.051 for diastolic BP z score; P = 0.067 for systolic prehypertension). There were significant associations between log transformed PLM index and daytime systolic and mean BP z scores (P = 0.03 and 0.033 respectively) as well as that between log transformed PLM related arousal index (PLMSArI) and nocturnal diastolic and mean BP (P = 0.008 and 0.038 respectively).
  
  
  CONCLUSIONS
  PLMS was independently associated with a wide range of BP elevations, especially nocturnal indices. Future studies should examine the underlying pathophysiologic mechanisms and effects of PLMS treatment on BP.
authors.affiliation: Department of Psychiatry, The Chinese University of Hong Kong, Shatin Hospital, Shatin, Hong Kong SAR, China. ykwing@cuhk.edu.hk
authors.forename: Yun Kwok
authors.initials: YK
authors.lastname: Wing
authors.forename: Jihui
authors.initials: J
authors.lastname: Zhang
authors.forename: Crover Kwok Wah
authors.initials: CK
authors.lastname: Ho
authors.forename: Chun-Ting
authors.initials: CT
authors.lastname: Au
authors.forename: Albert Martin
authors.initials: AM
authors.lastname: Li
mesh_terms: D001794:Blood Pressure; D002648:Child; D002940:Circadian Rhythm; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D008297:Male; D018670:Monitoring, Ambulatory / Q000379:methods / Q000706:statistics & numerical data; D020189:Nocturnal Myoclonus Syndrome / Q000453:epidemiology*; D016017:Odds Ratio; D017286:Polysomnography / Q000379:methods / Q000706:statistics & numerical data