74.
Validation of physical activity by means of an activity monitor during
simulated free living in patients with osteoarthritis of the hip.
Andreas Hermann, Mathias Ried-Larsen, Andreas Kryger Jensen, Lars Bo
Andersen, Søren Overgaard, Anders Holsgaard-Larsen
Institute of Clinical Research University of Southern Denmark; Institute for
Sport Sciences and Clinical Biomechanics , University of Southern Denmark;
Department of biostatistics Institute of Public Health , University of Southern
Denmark; Institute for Sport Sciences and Clinical Biomechanics , University
of Southern Denmark; Orthopedic Research Unit, Department of Orthopedics
and Traumatology , Odense University Hospital; Orthopedic Research Unit,
Department of Orthopedics and Traumatology , Odense University Hospital
Background:
The use of activity monitors (AM) as a surrogate measure for
physical activity has been applied in several clinical studies. However few
studies have validated the AM against the gold standard, indirect calorimetry
(
IC)
Purpose / Aim of Study:
To validate physical activity by means of AM
compared with IC during a simulated free living scenario in patients with
osteoarthritis (OA) of the hip pre or post total hip arthroplasty (THA)
Materials and Methods:
20
patients diagnosed with hip OA (10 pre- 10 post
THA). 40% female, Age: 63.3 ± 9.0, BMI: 23.7 ± 3.7. All patients completed a
2
hour scenario of simulated free living containing 8 different physical activity
types. Energy expenditure (EE) (Kcal/min) was estimated by a AM (Sense
Wear pro3 Armband (Body media Inc, Pittsburgh, PA, USA ) (SWA)) and
validated against indirect calorimetry by means of a portable unit (Cosmed
K4b²,Rome,Italy). Analysis of bias and variance was carried out using
functional ANOVA
Findings / Results:
SWA overestimated EE during all activities by 72 % (1.54
Kcal/min, 95%CI [1.27; 1.80]). Split by activity significant differences in bias
was observed. Overestimation of EE was observed during several activities:
Chair rest 88% (0.65 Kcal/min, 95%CI [0.46; 0.81]), normal gait speed 93%
(2.78
Kcal/min, 95%CI [2.29; 3.32]) and in household activities dominated by
upper body movements (gardening) 170% (4.37 Kcal/min, 95%CI [3.77;
5.06]).
Underestimation of EE by -25% (-1.06 Kcal/min, 95%CI [-1.81;-0.27])
was recorded during stair climb
Conclusions:
The tested AM generally overestimated the EE during most
common activities of low to medium intensity in the observed patient group.
However, the size and direction of the bias was dependent on the activity mode
which indicates limitations in the validity of the SWA among patients with hip
OA
