Objective physical activity assessment in patients with moderate to very severe CHF or COPD: a validation study

Physical inactivity in healthy subjects increases the risk of developing a
number of chronic diseases, such as chronic heart failure (CHF) and chronic
obstructive pulmonary disease (COPD). Indeed, physical inactivity is one of the
lifestyle-related health determinants. Therefore, guidelines recommend that a
minimum of 30 minutes of daily physical activity of moderate intensity is
necessary to maintain physical fitness, and those not meeting this standard are
considered insufficiently active.

Decreased weight bearing activity in daily life is likely to play a key role in
the development and progression of skeletal muscle weakness and a poor exercise
performance in patients with CHF or COPD. Indeed, a *downward disease spiral*
has been hypothesized, in which advancing dyspnoea leads to a sedentary
lifestyle and de-conditioning of the lower-limb muscles, and thus further daily
physical inactivity. Moreover, exercise-based cardiopulmonary rehabilitation
programs have been shown to effectively improve quality of life, lower-limb
muscle function and exercise capacity in patients with CHF or COPD which cannot
be attributed to changes in left ventricular ejection fraction (LVEF) or forced
expiratory volume in the first second (FEV1), respectively.

Daily physical activity is clearly a different domain of outcome assessment
from the traditional measures of cardiopulmonary function and exercise
performance in patients with CHF or COPD. Indeed, an increased exercise
capacity does not necessarily result in a more active lifestyle. Therefore,
objective assessment of daily physical activity levels seems clinically
relevant and provides greater insight into the lives of patients with CHF or
COPD.

Questionnaires show limited validity and reliability to objectively assess
physical activity level, while wearable motion sensors gain in popularity as a
method to objectify daily life activity. Therefore, the aim of this study is to
validate a new activity monitor in both healthy subjects and in patients with
moderate to very severe CHF or COPD.

Validate a new activity monitor in both healthy subjects and in patients with
moderate to very severe CHF or COPD.

The new activity monitor that will be used in this study is the Data
Acquisition and Analysis unit for Fall and Balance (DAAFB) system developed by
Maastricht Instruments bv in Maastricht, the Netherlands. The DAAFB contains a
triaxial piezoresistive accelerometer and weighs 102 gram and has a range of ±
4g with a resolution of 0.02g. The measured signal will be stored on a 2 GB
micro SD cart at a sample rate of 102 Hz. Matlab(c) software and algorithms
will be used to calculate movement intensity and time spend in different
postures and movement-related activity.

To validate the DAAFB, two studies are designed. Study A evaluates the accuracy
of the activity monitor in healthy subjects using a standardized protocol.
Study B evaluates the accuracy of the activity monitor in patients with
clinically stable CHF or COPD during one hour of unconstrained activity
assessment. In both studies the results of two placements of the DAAFB will be
compared: on the frontal part of the thigh just above the knee (DAAFBleg) and
on the lower back at the height of the second lumbar vertebra, nearby the
body*s centre of mass (DAAFBtrunk). The DAAFB*s will be attached using elastic
belts.

Study A: A group of five healthy subjects will be recruited at the Maastricht
University Medical Centre (MUMC+). Subjects will be informed verbally and via
an information letter (see document E1). After that subjects will have at least
one day for reflection before they decide if they want to participate. In the
afternoon the same day the subjects undergo a standardized protocol: standing
upright (120 s), sitting upright (120 s), lying flat (120 s), walking at a
self-selected speed (120 s), and cycling at a self-selected speed (120 s).
Between different activities and/or postures, subjects have 30 seconds
transition time. In addition, we will investigate if the DAAFBtrunk and
DAAFBleg can accurately reflect subject*s movement intensity. For this purpose,
subjects will be asked to walk on a treadmill at five different walking speeds
(1.5, 2.5, 3.5, 4.5, 5.5 and 6.5 km/h). Other variables that will be taken into
account are date of birth, gender, weight and length. The total duration will
be one hour.

Study B: Five patients with CHF and five patients with COPD will be recruited
at Ciro, a centre of expertise for chronic organ failure in Horn, the
Netherlands. All assessments will be integrated in the clinical routine.
Subjects will be informed verbally and via an information letter (see document
E1). Patients will be asked to wear the DAAFBtrunk and the DAAFBleg
simultaneously for one hour and are instructed to continue their normal daily
routine. After one hour, patients will be asked to estimate their time spent on
non-weight bearing postures (e.g., sitting or lying), weight bearing postures
(e.g., standing) and dynamic activity (e.g., walking). Video recordings will be
used as the criterion standard. Patients will be videotaped while they wear the
DAAFB*s. After the recordings, the tapes will be analyzed by one examiner, who
will be blinded to the values obtained by the DAAFB*s and patients* estimation.
Video recordings will be compared to the output of the DAAFBtrunk, DAAFBleg and
patients* estimation. Date of birth, gender, length and weight, will be
obtained from their medical recordings. The total duration will be 1.5 hours.

Not applicable