Physical activity, physical function and arterial stiffness of people undergoing maintenance haemodialysis for stage 5 chronic kidney disease
Prescott, S. (2015) Physical activity, physical function and arterial stiffness of people undergoing maintenance haemodialysis for stage 5 chronic kidney disease, no. 377.
This thesis addresses current issues regarding assessment of physical activity (PA) and physical function (PF) status of haemodialysis (HD) patients, specifically: What is the recommended wear time to provide a reliable accelerometer estimate of habitual PA and sedentary behaviour? Can similar outcomes from different accelerometers be used interchangeably? Do subjectively and objectively estimated PA outcomes agree closely enough to be pooled? Which PF assessments are potentially most ‘useful’? This thesis also explores potential risk factors of arterial stiffness, a strong predictor of mortality in this population. A PA reliability study involving 70 maintenance HD patients (55.9 ± 15.7 years) over a seven-day monitoring period indicated one dialysis day and two non-diaysis days with a minimum of eight hours wear per day would provide reliable estimates of PA and sedentary behaviour regardless of accelerometer employed, and allowed 90% sample retention. Concordance studies indicated broad agreement for similar outcomes obtained via ActivPAL and Actigraph GT3X accelerometers but they were not interchangeable. ActivPAL is recommended for monitoring steps taken and time seated, Actigraph activity count output for total/overall PA. Questionnaire and accelerometer estimated PA outcomes may not be used interchangeably or pooled. More of the shared variance of physical performance was explained by clinical, demographic and habitual PA factors than for self-reported functional status thus recommending the former. Age, blood pressure and HD vintage were determinants of arterial stiffness, however PA and cardiorespiratory fitness did not appear to be risk factors in this sample. This thesis makes clear recommendations regarding implementation of PA and PF assessment methods, and illustrates their application on sample retention, as well as characterising and potentially identifying individuals at risk of poor outcomes. Emergence of HD vintage as a risk factor for arterial stiffness underscores the need for further research into adjunctive lifestyle interventions to manage health threats in this population.