Understanding why older people participate in clinical trials: the experience of the Scottish PROSPER participants

Background: over the next 20 years it is anticipated that there will be a significant increase in those aged 75 and over, and a consequent increase in cardiovascular disease, cancer and chronic illness. As this shift takes effect, there will be an increased need for treatment strategies that are of known benefit to this age group and a consequent rise in demand for clinical trials that are conducted specifically with the older population. Because factors that motivate older individuals to participate in clinical trials may differ from those that influence younger adults, it is important to evaluate the strategies used to encourage recruitment and retention and to determine how appropriate these are. Aim: evaluation of the reasons why subjects agree to participate in a controlled clinical trial of vascular disease prevention and the strategies used to improve compliance and protocol adherence. Setting: Scotland. Subjects: 2,520 Prospective Study of Pravastatin in the Elderly at Risk participants, aged 70–82 with either pre-existing vascular disease or at least one major vascular risk factor (hypertension, cigarette smoking, or diabetes mellitus). Design of study: two-stage iterative survey. Stage I was exploratory. Results: curiosity, or an interest in finding out more about the study, ‘a desire to support research’, and anticipated personal benefits, such as health screening, were the most important motivators for generating initial interest in the trial. Ongoing health monitoring was the most important recruitment and retention motivator (P = 0.001). Conclusions: curiosity, self interest and altruism may act as motivators at different points in the study time-line. However, fostering positive relationships between staff and recruits, and keeping recruits informed about the progress of the study are likely to maximise the retention of older subjects to long-term trials.