Authors：Che-Chang Yang (2010-09-22);
recommended: Yeh-Liang Hsu (2010-02-21)
Note: This article is the Chapter 1 of Che-Chang Yang’s doctoral thesis “Development
of a Home Telehealth System for Telemonitoring Physical Activity and Mobility
of the Elderly”.
1.1.1 Functional ability, mobility and ageing
elder population is rapidly growing. The World Health Organization (WHO) predicts
the global population proportion over 60 to reach 22% in 2050 [WHO Global
Health Observatory, 2009]. Taiwan
has also become an ageing society. The population proportion aged 65 and over
in Taiwan accounted for 7% in 1993, and this figure reached 10.6% in 2009
[Ministry of Interior, Taiwan, 2010]. With the continuing growth of elderly
population and a decline in birth rate, it is important to help people remain
independent and active. Maintaining autonomy and independence of the elderly is
the key goal in the “Active Ageing” policy led by the WHO. The “International
Plan of Action on Ageing” prompted by the United Nations (UN) has also adapted
independence as one of “United Nations Principles for Older Persons” to
encourage governments to incorporate the principles into their national
programs or policies [United Nations, 2002].
process of the elderly results in declined functional status and decreased
mobility, which affects their level of self-care and independence. Functional
status can be defined as the ability to perform activities necessary to ensure
well-being, and it can be assessed by examining the ability to carry out
various activities of daily living (ADLs). [Heikkinen, 1998]. Limitations in
basic ADLs and instrumental ADLs (IADLs) are strongly associated with less
mobility [Shimada et al., 2010]. Katz
et al. indentified 6 basic ADL items
associated with one’s living independence: bathing, dressing, toileting, transfer,
continence and feeding. The IADLs further describe the ability of performing
more complex ADLs in telephone use, shopping, food preparation, housekeeping,
laundry, transportation, handling medication and finances. The Katz ADL Scales
and IADL Scales have both been developed over the past decades to assess
independence [Katz et al., 1970;
1976; Lawton et al., 1969]. Currently
the Barthel Index (BI) and its modified version (MBI) have been widely accepted
as the basis of ADL/IADL assessment tool to evaluate the independence of
Mobility is a
crucial aspect regarding one’s living independence. It is sensitive to changes
in health and psychological status and is one of the most crucial factors
determining one’s functional capacity [Celler et al., 1994; Heikkinen, 1998]. Physical activity is regarded as
any bodily movement produced by skeletal muscles and results in energy
expenditure [Caspersen et al., 1985]. Limited physical activity (PA)and mobility are associated with a
deterioration of health and functional impairment in the elderly people [Folden
et al., 1990]. Impaired mobility due
to age-related loss of muscle strength also increases the risk of falls
[Buchner, 1997]. Among the 10 activity assessment items(feeding, bathing,
grooming, dressing, bowels, bladder, toilet use, transfers, mobility, and
stairs) in the Barthel Index, “transfers” and “mobility” score higher (15%
each) than other 8 items. The Modified Barthel Index also adopts the two items “ambulation”
and “bed/chair transfer” to assess mobility. The Elderly Mobility Scale (EMS)
has been developed to assess the functional performances in locomotion,
balance, gait and postural transitions, in which balance and gait are the two
most significant factors for mobility and fall risk [Smith, 1994; Daley et al., 2000]. Mobility can also be
related to the performance of PA which focuses primarily on its activity
intensity (or energy expenditure, EE). The Physical Activity Scale for the
Elderly (PASE) was also developed to assess the duration and intensity due to
physical activity [Washburn et al.,
1.1.2 Applicability of monitoring functional status and mobility using home
assessment methods have been developed and validated for assessing the functional
status and mobility of elderly people, technologies are expected to facilitate
and provide cost-effective and practical assessment alternatives. Researchers
have attempted to develop remote monitoring approach to health status of the
elderly at home. Celler et al. [1994,
1995] tried to identify changes of health status from simple activity measures
automatically and continuously collected by a number of sensors. A telemedicine
platform was also used to enable effective data transmission and collection, as
well as to prompt timely response and intervention. Such a concept and trial
initiated the possibility of monitoring mobility and functional status of the
elderly people at home with the use of available technologies.
(1) Sensor-based approaches to monitoring functional status and mobility
advances in sensors and telecommunication technologies, human activities can be
monitored by means of sensors. The rationale and advantages of utilizing such
sensor-based approaches are:
Quantitative and objective:
The activities are recorded by sensors. The functional status can be assessed
objectively according to the quantitative data, avoiding varied and
inconsistent assessment results due to subjective evaluation methods, such as
questionnaires and self-reports.
Continuous, long-term monitoring: For the elderly living in their home environment, the transition
from functionally healthy to functionally ill might not be easily perceived by
themselves or be observed by periodical care interventions. Sensor-based
monitoring approaches can provide continuous monitoring to assess functional
status on a long-term basis.
subjects are not aware of the monitoring facilities in use and hence the
systems do not interfere or even change their daily activities and life styles.
This minimizes the so-called “white coat effect” possibly brought by
traditional assessment methods.
Celler et al.  proposed the concept of
implementing sensor networks in a home environment to monitor functional status
of the elderly living alone. For measuring ADLs, passive infrared sensors
(PIRs) and switches are commonly used to detect the occupancy of human in space
(home) and location transfer. Electricity sensors can be used to detect the use
of home appliances [Franco et al.,
2008]. Motion sensors can also be used to measure human activities. Currently
accelerometry has been widely used in the study of physical activity and
mobility due to advances in sensor technology (MEMS accelerometers). Accelerometry
is preferred because acceleration is proportional to external force and hence
can reflect the intensity and frequency of human movement. Accelerometry data
can be used to derive information of velocity and displacement data by
integration accelerometry data with respect to time. Therefore, accelerometry
is capable of providing sufficient information for measuring physical activity
and a range of human activities. Accelerometers have been widely accepted as
useful and practical sensors for wearable devices to measure and assess
physical activity in either clinical/laboratory settings or a free-living
environment. Several accelerometry-based applications have also been identified
[Mathie et al., 2004].
(2) Integrating with home telehealth systems
Telehealth is a
broader concept than telemedicine. In the U. S. governmental report,
telehealth is defined as “the use of electronic information and
telecommunications technologies to support long-distance clinical health care,
patient and professional health-related education, public health and health
administration.” [U. S. Department of Health and Human Services, 2001]
Telehealth is a practical approach that connects individuals and healthcare
providers through telecommunication technology in a variety of application
modalities in locations other than hospitals or clinics [Mann, 2005].
Nations Principles for Older Persons” has addressed that elderly people should
be able to reside at home as long as possible, and consequently home has become
the centerpiece of healthcare delivery system today. Telehomecare, or the more
modern term “home telehealth”, is a relatively recent innovation. According to
the Canadian governmental report, telehomecare is defined as “the use of
information and communication technologies to enable effective delivery and
management of health services at a patient’s residence” [Office of Health and
Information Highway, 1998]. Home telehealth refers to the use, by a home care
provider, of modern telecommunication and information technology to link
patients to single or multiple out-of-home sources of care information,
education, or service over short or long distances [Koch, 2006]. Home
telehealth differs from telemedicine in the sense that people who transmit and
receive medical information are not necessarily medical doctors but the
patients themselves and their families, nurses, care-givers, home-helpers and
medical technical experts, etc [Tsuji, 2002]. A study suggested that home
telehealth services may enhance the users’ timely accessibility to necessary
healthcare, reduce preventable hospitalization and decrease direct and indirect
medical costs over time [Jia, et al.,
working on activity telemonitoring solutions for the elderly living at home.
Objective and quantitative data obtained by sensor-based monitoring techniques
can be used to assess functional health as well as to evaluate the levels of
necessary medical treatments or care services. Ní Scanaill et al.  reviewed several mobility telemonitoring
approaches, i.e., the “health smart homes” and wearable systems of different
technological complexity that connect home telehealth systems.
Gerontechnology Research Center (GRC, http://grc.yzu.edu.tw) of Yuan Ze
University has also been developing a range of home telehealth-based
applications. The concept of “Decentralized Home Telehealth System (DHTS)” has
been proposed, and what sets this system innovative from most others is its
focus on a highly decentralized monitoring modality and the portable nature of
the system [Hsu et al., 2007]. Figure
1 illustrates the information structure of the DHTS. The distributed data
server (DDS) is the core unit of DHTS and it has four main functions: receiving
data from remote sensors and devices, data logging (MMC stick), data processing
and Internet communication. The Internet accessibility of the DDS offers the
integratibility to telehealth application and Internet-enabled capabilities.
For data request, the DDS can be directly accessed from remote authorized
clients using the Internet browsers (e.g., the IE), Visual Basic (VB) or
JAVA-supported application programs. This proposed system also provides timely
alert reports that respond to emergent events, such as falls or irregular
activities. A centralized database can be optionally connected to DHTS if
additional applications are required.
Figure 1. The structure of the DHTS
Figure 2 shows
the DHTS application fields developed by GRC. Based on the DHTS architecture,
five application fields, including environmental monitoring [Cheng et al., 2006], vital sign healthcare,
sleep quality monitoring and evaluation [Cheng et al., 2008], telepresence interaction and healthcare robotics
[Tsai et al., 2007], and mobility
monitoring [Yang et al., 2009] have
Figure 2. The applications of the decentralized
home telehealth system developed by GRC
Purpose of this research
home activity monitoring techniques and field tests have been presented,
further research is still needed to develop a monitoring system integrating
accelerometry-based wearable motion detectors and home ADL sensors for the use
of monitoring and assessing functional status and mobility of the elderly
living at home. Therefore, it is expected that elderly people living alone in
their residences may benefit from a home telehealth system that offers simple,
low cost, and effective functional status and mobility monitoring and
The purpose of
this research is to develop an activity monitoring system for mobility and
functional ability telemonitoring for elderly people living at home. This
system is integrated with the DHTS for home use. Figure 3 illustrates the
framework of the proposed system. The wearable motion detector (WMD) and home
ADL sensors are used to monitor daily activities of the elderly at home. The
WMD is a waist-mounted device that uses a tri-axial accelerometer to measure
accelerations and tilt angles with respect to the three orthogonal directions
(vertical, antero-posterior, medio-lateral). The home ADL sensors are
distributed in several locations of interests in a home environment. Passive
infrared (PIR) sensors and CT (current transformer) are used to detect home
ADLs of the elderly. The activities collected from both the WMD and the home
ADL sensors are transmitted to the distributed data server (DDS) via wireless
sensor network (WSN) technology.
Figure 3. The system diagram of the proposed
Figure 4 further
describes the functional framework of the proposed system. Signal processing
algorithms are implemented in the WMD to enable real-time activity
classification, EE estimation, gait recognition and fall detection. Those identification
measures are transmitted to the home DDS. This system also incorporates ADL
events that are collected by the home ADL sensors. External application applet
or application program containing data analysis scheme can be applied to the
data stored in the database and hence facilitates the quantitative assessment
of mobility and functional status.
Figure 4. The functional framework of the proposed
dissertation is organized as follows. Chapter 2 reviews the accelerometry for
physical activity monitoring. Chapter 3 describes the instrument design of the
wearable motion detector and the distributed data server. The uses of the
wearable motion detector for mobility telemonitoring, including real-time
activity classification, EE estimation, gait recognition, and fall detection
are presented in Chapter 4 to 6. The design and use of home ADL sensors for ADL
telemonitoring is further presented in Chapter 7, while Chapter 8 discusses the
mobility assessment and concludes this research.
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