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Title: An exploratory study of mobility-related outcome measures and an exercise intervention in people with Huntington's Disease (HD)
Author: Khalil, Hanan
ISNI:       0000 0004 2733 5871
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2012
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Objective: There is emerging evidence that exercise may modify disease progression and improve function in a number of neurodegenerative diseases, but this has not been systematically studied in Huntington.s disease (HD). The purpose of this study was to evaluate feasibility, acceptability and benefits of an exercise programme in people with HD. Methods: Using a randomised controlled trial design, 25 participants with manifest HD were allocated to either intervention (home-based exercise; n=13) or control (usual care;n=12) groups. Participants were assessed at baseline and eight weeks later. Eleven participants from the exercise and 10 from the control group completed the intervention study. The primary outcome was gait variability (stride time coefficient of variation (CV)). Secondary outcomes included other measures of gait, disease-specific motor scale and measures of balance, muscle strength, mobility and community walking, functional performance in ADL and quality of life. These measures were included to reflect a range of physical impairments and activity limitations seen in people with HD. Analysis of covariance was used to compare follow-up scores across groups after adjustment for differences at baseline. Effect sizes were calculated for outcome measures based on differences in change scores between groups. Process interviews were conducted at the end of the study to determine acceptability of the intervention to participants. Cross sectional investigation of outcome measures was undertaken initially to investigate discriminant and concurrent validity as well as test re-test reliability and minimal detectable change (MDC95) along the broad spectrum of the disease. Baseline data from 25 participants with manifest HD (who went on to participate in the intervention), in addition to data from 17 individuals with pre-manifest HD and 25 healthy controls were analysed. This data was of use in interpreting the results from the interventional study. In particular, the MDC95 data helped in determining of whether any statistical significant changes due to the intervention are clinically meaningful. Results: Measures of gait variability, some measures of balance, community walking and measures of functional performance in ADL were able to distinguish between people with manifest HD and pre-manifest HD as well as between people with pre-manifest HD and healthy controls suggesting good discriminant validity. All these outcomes had also good concurrent validity with a disease specific motor score. The test re-tests reliability scores for the majority of the outcomes were high and the MDC95 scores were low, suggesting that the individual variability on these outcomes were low. Adherence rates to the exercise programme were high (78.8% of participants reported completion of at least 78% of the prescribed sessions). Participants in the intervention group demonstrated significant improvement in stride time CV (95% CI (-11.5, -0.6))based on complete case analysis. Significant differences between groups were also observed in the disease-specific motor scale and in measures of balance, mobility,community walking and functional performance in ADL, but not muscle strength and health-related quality of life. Effect sizes were large (>0.8) for the majority of the outcomes. The magnitude of the change as a result of the exercise intervention exceeded the calculated MDC95 values for some of the outcomes, which suggest that most of the observed changes are clinically meaningful. Qualitative feedback from the participants who completed the exercise programme suggested high levels of acceptability with positive impact on general health and mobility. Participants identified barriers and facilitators that affected performing the exercises at home and described management strategies that helped adherence to the exercise programme. Conclusions: This study was the first systematic trial to demonstrate that a short-term structured exercise programme is acceptable and can be safely delivered in a home environment; achieve good adherence; and positively affect body function and activity in people with HD. The sensitivity of the outcomes as determined in the cross-sectional study, to mobility deficits the in pre-manifest HD group is important. These outcomes has the potential to be used in future studies of exercise interventions in the premanifest stage which aim to target such deficits early in the disease life cycle, before they begin to impact on a person.s ability to participate in the community. Overall the data presented from this study provides a platform for further investigations to extend these findings about the role of exercise and physical activity in people with HD. Larger and more detailed studies are needed to replicate findings from this study in othercontexts and variations in dose.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry