A qualitative investigation of reasoning behind decisions to decline participation in a research intervention: A study-within-a-trial.

The current study-within-a-trial explored individuals' decisions to decline participation in research trialling a chronic illness-focused therapy (i.e. multiple sclerosis). Four themes were identified from seven semi-structured interviews with participation decliners and were confirmed by the host trial's Patient & Public Involvement (PPI) panel: acknowledgement of the value of research; 'fit' of the study; misinterpretation of participant information; and 'ignorance is bliss' - discussed in light of theory and research. This study-within-a-trial extends research on trial recruitment and participation decline; while also suggesting that PPI can be utilised in both a practical and impactful manner.