A discrete choice experiment to quantify the influence of trial features on the decision to participate in cystic fibrosis trials.

Background: Patient-centred trial design optimises recruitment and retention, reduces trial failure rates and increases the diversity of trial cohorts. This allows safe and effective treatments to reach clinic more quickly. To achieve this, patients' views must be incorporated into trial design.

Methods: A discrete choice experiment was used to quantify preferences of pwCF for trials features; medicine type, trial location, stipend, washout, drug access on trial completion and trial design. Respondents were presented pairs of hypothetical trial scenarios with different level combinations assigned through experimental design. Respondents were asked to pick their preferred option or decline both. The cross-sectional data were explored using a Random Parameters Logit model.

Results: We received 207 eligible responses between Oct2020-Jan2021. The strongest influence on the decision to participate was trial location; pwCF favour participation at their usual clinical centre. Greater travel distances made respondents less willing to participate. Post-trial drug access ranked second. pwCF would rather participate in modulator trials than trials of other drugs. In general, pwCF did not favour a washout period, but were more prepared to washout non-modulators than modulators. Stipend provision was not ranked highly, but higher stipends increased intention to participate. Trial design (placebo vs open-label) had minimal influence on the decision to participate. There are complex interactions between placebos and washouts.

Conclusions: We used quantitative methods to systematically elicit preferences of pwCF for clinical trials' features. We explore the relevance of our findings to trial design and delivery in the current CF trials landscape.