title: Measuring the lifespace of people with Parkinson's disease using smartphones: proof of principle.
abstract: BACKGROUND
  Lifespace is a multidimensional construct that describes the geographic area in which a person lives and conducts their activities, and reflects mobility, health, and well-being. Traditionally, it has been measured by asking older people to self-report the length and frequency of trips taken and assistance required. Global Positioning System (GPS) sensors on smartphones have been used to measure Lifespace of older people, but not with people with Parkinson's disease (PD).
  
  
  OBJECTIVE
  The objective of this study was to investigate whether GPS data collected via smartphones could be used to indicate the Lifespace of people with PD.
  
  
  METHODS
  The dataset was supplied via the Michael J Fox Foundation Data Challenge and included 9 people with PD and 7 approximately matched controls. Participants carried smartphones with GPS sensors over two months. Data analysis compared the PD group and the control group. The impact of symptom severity on Lifespace was also investigated.
  
  
  RESULTS
  Visualization methods for comparing Lifespace were developed including scatterplots and heatmaps. Lifespace metrics for comparison included average daily distance, percentage of time spent at home, and number of trips into the community. There were no significant differences between the PD and the control groups on Lifespace metrics. Visual representations of Lifespace were organized based on the self-reported severity of symptoms, suggesting a trend of decreasing Lifespace with increasing PD symptoms.
  
  
  CONCLUSIONS
  Lifespace measured by GPS-enabled smartphones may be a useful concept to measure the progression of PD and the impact of various therapies and rehabilitation programs. Directions for future use of GPS-based Lifespace are provided.
authors.affiliation: UQ Centre for Clinical Research, Asia-Pacific Centre for Neuromodulation, The University of Queensland, Herston, QLD, Australia. j.liddle@uq.edu.au.
authors.forename: Jacki
authors.initials: J
authors.lastname: Liddle
authors.forename: David
authors.initials: D
authors.lastname: Ireland
authors.forename: Simon J
authors.initials: SJ
authors.lastname: McBride
authors.forename: Sandra G
authors.initials: SG
authors.lastname: Brauer
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Hall
authors.forename: Hang
authors.initials: H
authors.lastname: Ding
authors.forename: Mohan
authors.initials: M
authors.lastname: Karunanithi
authors.forename: Paul W
authors.initials: PW
authors.lastname: Hodges
authors.forename: Deborah
authors.initials: D
authors.lastname: Theodoros
authors.forename: Peter A
authors.initials: PA
authors.lastname: Silburn
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Chenery
keywords: Parkinson's disease; community; mHealth; telemedicine
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