Assessing control of postural stability in community-living older adults using performance-based limits of stability

<p>Abstract</p> <p>Background</p> <p>Balance disability measurements routinely used to identify fall risks in frail populations have limited value in the early detection of postural stability deficits in community-living older adults. The objectives of the study were to 1) measure performance-based limits of stability (LOS) in community-living older adults and compare them to theoretical LOS computed from data proposed by the Balance Master^®system, 2) explore the feasibility of a new measurement approach based on the assessment of postural stability during weight-shifting tasks at performance-based LOS, 3) quantify intra-session performance variability during multiple trials using the performance-based LOS paradigm.</p> <p>Methods</p> <p>Twenty-four healthy community-living older adults (10 men, 14 women) aged between 62 to 85 (mean age ± sd, 71.5 ± 6 yrs) participated in the study. Subjects' performance-based LOS were established by asking them to transfer their body weight as far as possible in three directions (forward, right and left) without changing their base of support. LOS were computed as the maximal excursion of the COP in each direction among three trials. Participants then performed two experimental tasks that consisted in controlling, with the assistance of visual feedback, their centre of pressure (COP) within two predefined targets set at 100% of their performance-based LOS. For each tasks 8 trials were performed. Ground reaction forces and torques during performance-based LOS evaluation and experimental tasks were recorded with a force plate. Sway area and medio-lateral mean COP displacement speed variables were extracted from force plate recordings.</p> <p>Results</p> <p>Significant differences between theoretical LOS computed from maximum leaning angles derived from anthropometric characteristics and performance-based LOS were observed. Results showed that a motor learning effect was present as the participants optimized their weight-shifting strategy through the first three trials of each task using the visual biofeedback provided on their COP. Reliable measures of control of postural stability at performance-based LOS can be obtained after two additional trials after the learning phase (0.69 > ICC > 1.0).</p> <p>Conclusion</p> <p>Establishing performance-based LOS instead of relying on estimations of theoretical LOS offers a more individualized and realistic insight on the true LOS of an individual. Performance-based LOS can be used as targets during weight-shifting postural tasks with real time visual feedback of the COP displacement to assess postural stability of community-living older adults. In order to obtain reliable results, a learning phase allowing subjects to learn how to control their COP displacement is needed.</p

Reliability and validity of a new dexterity questionnaire (DextQ-24) in parkinson's disease

BACKGROUND: Patients with Parkinson's disease exhibit disturbed dexterity. Validated self-reported outcomes for dexterity in Parkinson's disease are lacking. The aim of this study was to investigate the reliability, content and construct validity of a new Dexterity Questionnaire 24. METHODS: One hundred and three patients with Parkinson's disease completed the Dexterity Questionnaire 24 (score range 24-96), at baseline and four weeks later. The internal consistency was determined. Test-retest reliability was assessed in a subgroup (N = 44). Standard error of measurements and the minimal detectable change were defined. The construct validity was examined in the whole group (N = 103). Floor and ceiling effects were investigated. RESULTS: The internal consistency of the Dexterity Questionnaire 24 was high (α = 0.91). High test-retest reliability was found (Intra Class Correlation Coefficient = 0.91, Confidence interval: 0.84-0.95). Standard error of measurement was 2.9 and minimal detectable change was 8 points. (i.e., 11%). Good structural, convergent and divergent validity of the Dexterity questionnaire 24 was found (r = 0.73 with Activities of Daily Living-subscale of the Parkinson's Disease Questionnaire-39, and r = 0.66, and r = 0.50, p-values all < 0.0001, respectively with the subscales II and III of the Movement Disorders Society-Unified Parkinson Disease Rating Scale). Low not significant correlations were found between the Dexterity Questionnaire 24 and the subscales stigma and social support (r = 0.20, and r = 0.14 respectively). No floor or ceiling effects were found for the total Dexterity Questionnaire 24. CONCLUSION: The Dexterity Questionnaire 24 is valid and reliable for evaluating dexterity in patients with Parkinson's disease