Patient recruitment and experiences in a randomised trial of supervised exercise training for individuals with abdominal aortic aneurysm

We sought to describe patient recruitment and experiences in a randomised controlled trial of a 12-week (thrice weekly) supervised exercise program for patients with small abdominal aortic aneurysm (AAA). Potential patients were identified via AAA surveillance lists and vascular clinics and invited to participate in the study. Upon completion of baseline assessments, patients were randomly allocated 1:1 to exercise or usual care. Patients completing the exercise arm were invited to attend a focus group session to explore experiences of diagnosis, management of condition, trial recruitment, and expectations and experiences of the exercise program. Between January 2010 and September 2011, 545 patients were identified. The response rate to postal invitation was 81.7% (445/545), with 108 patients responding as “interested.” Only 28 of these patients were eligible and recruited (46.7% of recruitment target), yielding an overall recruitment rate of 5.1%. However, the estimated recruitment rate among eligible patients was 23.7%. Twenty-five patients (89.3%) completed the study, and compliance to the exercise program was 94%. Participants attending the focus group session indicated that the exercise program was manageable, beneficial, and enjoyable. The feasibility of supervised exercise training in individuals with small AAA remains unclear. Our study revealed a poorer than expected recruitment rate, but good compliance to, and feedback for, the exercise intervention. We present potential explanations for these findings and suggestions for future trials involving similar populations. Abdominal aortic aneurysm (AAA) is a frequently lethal age-related disease affecting 5% to 7.5% of men and 1.5% to 3% of women aged >65 years.1 Mechanical intervention (open surgical or endovascular repair) is currently the only treatment shown to be effective in preventing AAA rupture and aneurysm-related death; it is reserved for AAA >5.5 cm in diameter for men and >5.0 cm in women.2 Unfortunately, there are currently few treatment options available for inhibiting AAA expansion in individuals with small AAA (3.0 to 4.9 cm)2 and 3; most patients simply enter a surveillance program to monitor the progression of their aneurysm. Recently, there has been a growing interest in the role of exercise training in reducing AAA progression and increasing fitness for surgery in individuals with small AAA4, 5 and 6; however, no previous studies have provided detailed information about the effectiveness of recruitment strategies. Recruitment is considered a difficult aspect of the study process,7 and it has implications for the statistical power that can be demonstrated by trials and their subsequent value. Beside limited information on recruitment, it is also unclear how individuals with AAA evaluate supervised exercise training. Understanding patient perspectives of primary and adjunctive treatments is necessary to optimize patient care. We recently completed a pilot study of supervised exercise training in patients with small AAA.4 Recruitment to this study was difficult, with uptake of <50% of our original target. The purpose of this paper was to provide a detailed report of our recruitment strategies and results with a view to informing future trials, and to highlight the findings of a focus group session that allowed participants to reflect on and share their experiences.