Abdominal aortic aneurysm (AAA) affects 4% of men aged 65-79, a prevalence rising as our population ages. As most patients suffering rupture die immediately, elective AAA repair is critical and the National AAA Screening Programme (NAAASP) is being implemented across the UK to identify AAAs for elective repair. Manchester is the first major urban population to be screened. The UK had the highest mortality rates following elective open AAA repair in Europe (7% v 3.5%); the AAA Quality Improvement Programme's (AAAQIP) target is to reduce this to under 3.5% by 2013.
The benefits of exercise across a broad spectrum of medical conditions are now increasingly recognised; especially in the elderly. Exercise training may reduce mortality and complications in major surgery. Cardiopulmonary exercise testing (CPET) measures cardiopulmonary reserve and predicts outcome in major surgery. The Manchester CPET study group demonstrated that anaerobic threshold (AT) and peak oxygen consumption (VO2 peak) predict 30 and 90-day mortality in elective AAA repair.
The investigators propose a pilot randomised controlled trial (RCT) to determine whether a structured exercise programme improves fitness measured by CPET, and the optimal duration of training for AAA surgery. As over 90% of AAAs detected by screening are \< 5.5cm and enter surveillance, these patients offer a unique opportunity to explore the ideal duration of exercise training as surgery is not indicated for months or years.
100 participants on AAA surveillance will be recruited and randomised to either exercise training or standard preoperative care (50 in each arm) to answer the following research questions:
1. Can a supervised exercise programme improve performance in CPET measures that predict outcome in AAA surgery?
2. What is the optimal period of training needed to achieve a significant improvement in CPET scores?
3. How long is any exercise-induced improvement in fitness sustained?
4. The economic and health costs of a supervised exercise training programme
Exercise subjects will attend a 60 minute supervised exercise programme of moderate intensity (70% of heart rate reserve) x3/week at a local gym. All participants will undergo CPET assessment of cardiopulmonary fitness and complete a health-related quality of life (Medical Outcomes Study 36-Item Short-Form Health Survey) at baseline and 18 weeks. The exercise subjects will undergo further CPET studies at 6, 12 and 36 weeks to investigate the duration of training needed to optimise fitness and the length of time improvements in fitness persist. Other important health related outcomes include blood pressure and lipid profile and frequency of health service visits (e.g. General Practitioner appointments) will be recorded for all participants at baseline and 18 weeks to provide data on the effects of exercise on health care costs. Longitudinal regression models, with Normal and Poisson distributions as appropriate, will be used to assess differences between the groups with respect to CPET changes, other health-related outcomes and frequency of health service visits over the whole study period. This pilot study will also explore strategies to encourage participation and compliance with exercise which may also improve general health outcomes and save National Health Service (NHS) costs by reducing demand.
The overall aim is to collect the data needed to design a definitive multicentre trial on whether physical exercise reduces morbidity and/or mortality in AAA repair.
Those aged \>65 are the fastest growing segment of our population. This pilot study will contribute to public health policy drive on the impact of physical activity on functional capacity, quality of life and independence.
