Impact of informed consent content and length on recruitment of older adults into a community based primary prevention trial.

Aims: To compare recruitment, refusal and randomisation rates of older adults into a general practice-based clinical trial with two versions (varied format, content and language) of the Participant Information and Consent Form (PICF).

Methods: This prospective PICF study was conducted within the STAREE (STAtins in Reducing Events in the Elderly) clinical trial. Participants phone screened between October 2015 to February 2016 formed Group 1 and were mailed the extended PICF version and participants phone screened between October 2016 to February 2017 formed Group 2 and were mailed the shortened PICF version. Participants who attended a subsequent baseline screening visit were guided through a comprehensive informed consent process.

Results: During the screening phase of the trial, the likelihood of refusing trial participation was lower in Group 2 compared to Group 1 equating to an overall 23% reduction in risk (RR 0.77, P = 0.005, 95% CI 0.62-0.95). Group 2 had a 6.4% higher randomisation rate compared with Group 1 (65.3% versus 58.9% respectively) but this difference was not statistically significant. Factors associated with trial participation were male gender, age between 70 and 75 years and living alone (all p < .0.05).

Conclusions: Whilst avoiding lengthy and complex PICF documents may assist with initial trial engagement, it needs to be supplemented with other strategies to support ongoing trial interest to randomisation and beyond. Participants refused trial participation throughout the screening phase indicating that the PICF was only one factor among several affecting an individual's decision to participate in this clinical trial.