title: Comparison of Commercial Wrist-Based and Smartphone Accelerometers, Actigraphy, and PSG in a Clinical Cohort of Children and Adolescents.
abstract: OBJECTIVE
  To compare two commercial sleep devices, an accelerometer worn as a wristband (UP by Jawbone) and a smartphone application (MotionX 24/7), against polysomnography (PSG) and actigraphy (Actiwatch2) in a clinical pediatric sample.
  
  
  METHODS
  Children and adolescents (n = 78, 65% male, mean age 8.4 ± 4.0 y) with suspected sleep disordered breathing (SDB), simultaneously wore an actiwatch, a commercial wrist-based device and had a smartphone with a sleep application activated placed near their right shoulder, during their diagnostic PSG. Outcome variables were sleep onset latency (SOL), total sleep time (TST), wake after sleep onset (WASO), and sleep efficiency (SE). Paired comparisons were made between PSG, actigraphy, UP, and MotionX 24/7. Epoch-by-epoch comparisons determined sensitivity, specificity, and accuracy between PSG, actigraphy, and UP. Bland-Altman plots determined level of agreement. Differences in bias between SDB severity and developmental age were assessed.
  
  
  RESULTS
  No differences in mean TST, WASO, or SE between PSG and actigraphy or PSG and UP were found. Actigraphy overestimated SOL (21 min). MotionX 24/7 underestimated SOL (12 min) and WASO (63 min), and overestimated TST (106 min) and SE (17%). UP showed good sensitivity (0.92) and accuracy (0.86) but poor specificity (0.66) when compared to PSG. Bland-Altman plots showed similar levels of bias in both actigraphy and UP. Bias did not differ by SDB severity, however was affected by age.
  
  
  CONCLUSIONS
  When compared to PSG, UP was analogous to Actiwatch2 and may have some clinical utility in children with sleep disordered breathing. MotionX 24/7 did not accurately reflect sleep or wake and should be used with caution.
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research and Department of Paediatrics, Monash University, Melbourne, Australia.|School of Psychological Sciences, Monash University, Melbourne, Australia.
authors.forename: Elicia
authors.initials: E
authors.lastname: Toon
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research and Department of Paediatrics, Monash University, Melbourne, Australia.|Melbourne Children's Sleep Centre, Monash Children's Hospital, Melbourne, Australia.
authors.forename: Margot J
authors.initials: MJ
authors.lastname: Davey
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research and Department of Paediatrics, Monash University, Melbourne, Australia.
authors.forename: Samantha L
authors.initials: SL
authors.lastname: Hollis
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research and Department of Paediatrics, Monash University, Melbourne, Australia.|Melbourne Children's Sleep Centre, Monash Children's Hospital, Melbourne, Australia.
authors.forename: Gillian M
authors.initials: GM
authors.lastname: Nixon
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research and Department of Paediatrics, Monash University, Melbourne, Australia.
authors.forename: Rosemary S C
authors.initials: RS
authors.lastname: Horne
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research and Department of Paediatrics, Monash University, Melbourne, Australia.
authors.forename: Sarah N
authors.initials: SN
authors.lastname: Biggs
mesh_terms: D061725:Accelerometry / Q000295:instrumentation* / Q000379:methods* / Q000706:statistics & numerical data; D056044:Actigraphy / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography / Q000379:methods* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012891:Sleep Apnea Syndromes / Q000175:diagnosis*; D000068997:Smartphone; D014953:Wrist
keywords: accelerometer; actigraphy; pediatrics; polysomnography