title: Patient-focused endpoints in advanced cancer: criterion-based validation of accelerometer-based activity monitoring.
abstract: OBJECTIVE
  Objective assessment of daily physical activity (PA) by body-worn accelerometers offers potential as a novel endpoint in the clinical management of advanced cancer patients. This study aimed to assess criterion-based validity of an accelerometer-based activity monitoring system (AM-system), ActivPAL™, using two different methods.
  
  
  METHODS
  Advanced cancer in patients and outpatients (Karnofsky Performance Status (KPS) 40-100). ActivPAL™ measurements were validated against (i) observations and (ii) energy expenditure (EE) measured by 2-week doubly-labelled water (DLW) protocol.
  
  
  RESULTS
  Absolute errors for mean time spent in different body positions (<0.1%) and number of transfers (0%) were low. Step count error was significantly higher in patients with KPS 40-60 (non-self caring) compared to KPS 70-100 (self-caring) (33 vs. 24%, p = 0.006). Post-hoc mathematical analysis demonstrated that absolute errors for the mean energy expenditure of activity (EEA) (1.4%) and mean total EE (0.4%) were low, but agreement was also low.
  
  
  CONCLUSIONS
  AM-systems provide valid estimates of body positions and transfers, but not step count, especially in non-self caring patients. ActivPAL™ can derive estimates of EE but there is considerable variability in results, which is consistent, in part, with the inaccuracy in step count. Further studies are required to assess the validity of different endpoints derived from AM-systems in advanced cancer patients.
authors: Clinical and Surgical Sciences (Surgery), University of Edinburgh, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, United Kingdom.
authors: Richard J E
authors: RJ
authors: Skipworth
authors: Guro B
authors: GB
authors: Stene
authors: Max
authors: M
authors: Dahele
authors: Paul O
authors: PO
authors: Hendry
authors: Alexandra C
authors: AC
authors: Small
authors: David
authors: D
authors: Blum
authors: Stein
authors: S
authors: Kaasa
authors: Peter
authors: P
authors: Trottenberg
authors: Lukas
authors: L
authors: Radbruch
authors: Florian
authors: F
authors: Strasser
authors: Tom
authors: T
authors: Preston
authors: Kenneth C H
authors: KC
authors: Fearon
authors: Jorunn L
authors: JL
authors: Helbostad
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002153:Calorimetry, Indirect; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D009043:Motor Activity / Q000502:physiology*; D009369:Neoplasms / Q000378:metabolism / Q000503:physiopathology*; D010865:Pilot Projects; D015203:Reproducibility of Results; D014741:Video Recording