Daily life physical activity (PA) of patients with peripheral arterial disease (PAD) may be severely hampered by intermittent claudication (IC). From a therapeutic as well as research standpoint, it may be more relevant to determine improvement in PA as outcome measure in IC. Aim of this study was to validate daily activities using a novel type of tri-axial accelerometer (MoveMonitor) in IC patients.
IC patients were studied during a hospital visit. Standard activities (locomotion, lying, sitting, standing, shuffling, number of steps and "not worn" detection) were video recorded and compared with activities scored by the MoveMonitor. Inter-rater reliability (expressed in Intraclass Correlation Coefficients (ICC)), sensitivity, specificity and predictive values (PPV) were calculated for each activity.
Twenty-eight hours of video observation were analysed (n=21). Our video annotation method (gold standard) appeared accurate for most postures (ICC>0.97) except for shuffling (ICC=0.38). The MoveMonitor showed high sensitivities (>86%), specificities (>91%) and PPV (>88%) for locomotion, lying, sitting and the "not worn" detection. Moderate accuracy was found for standing (46%), while shuffling appeared not detectable (18%). A strong correlation was found between video recordings and the MoveMonitor regarding the "number of steps" calculations (ICC=0.90).
The MoveMonitor provides accurate information on a diverse set of postures, daily activities and number of steps in IC patients. However, the detection of low amplitude movements such as shuffling and "sitting to standing" transfers is a matter of concern. This tool is useful to assess the role of physical activity as a novel clinically relevant outcome parameter in IC.