Abstract
Introduction: Parkinson's disease (PD) is an age-related neurological condition characterized by bradykinesia, tremor, and postural instability. Weight loss within the first year of diagnosis is associated with poor prognosis. Studies suggest that if older adults lose skeletal muscle, their risk of falls and related injuries increases. Therefore, measures of body composition (e.g. muscle, fat) are important in PD, where the risk of falls is high. Established body composition analysis equipment is bulky and only used in research settings. We tested the reliability of a portable SECA mBCA 525 device that has not been validated in PD. Method: We recruited 19 participants from Movement Disorder Clinics, with 11 household controls. Participants consented to body composition analysis using a SECA mBCA 525 device. It passes a mild electrical current between adhesive electrodes on the hands and feet to determine tissue impedance. Proprietary algorithms then use the impedance and manually collected data (weight, height, waist circumference and reported activity level) to estimate fat, lean, and water mass (kilograms). We performed this process at two visits a month apart to determine test-retest reliability. Results: We collected data from 24 participants: 10/11 control and 14/19 PD participants. All five PD participants with SECA data collection 'failures' had rest tremor. However, tremor amplitude was the same as the whole group average (mean 1.6, standard deviation 1.9 vs mean 1.6, standard deviation 1.2 for the whole group). There were no significant differences between estimates of lean- and fat mass between trials 1 and 2 (Bland-Altman plot and linear regression, p>0.05). Conclusions: The SECA mBCA 525 portable bio-impedance analysis device had good test-retest reliability for assessing lean- and fat mass in subjects with and without PD. However, data collection 'failures', which may be due to limb tremor, limit its usefulness in studies of people with PD