Some systematic reviews have identified capacity of preferences to impact on trial outcomes

[7] whereas others have not [8]. Zelen designs have also been developed for situations where seeking consent to be randomized may be problematic [9]. Systematic reviews provide evidence of the use of Zelen and patient preference designs in many areas [8] and [10], which might suggest that the underlying problems associated with disappointment, and their implications, are well understood. There have been valuable studies of public understanding of various aspects of randomization [11] and [12]. Qualitative studies have identified preferences to be potentially complex and dynamic, as well as being amenable to dedicated interventions [13]. How information about Rapamycin cost randomization is presented in seeking informed consent has received scrutiny [14] BMS-354825 and dedicated interventions have successfully enhanced informed consent and

recruitment to trials [15]. There are also qualitative studies investigating whether and how trial participants react to being randomized [16], though most such studies have been undertaken in clinical contexts where contextual effects may be pronounced, such as neo-natal intensive care units [17]. Cook and Campbell [3] have suggested possible responses to disappointment, ranging from control group participants trying harder by accessing interventions outside trials (termed

“compensatory rivalry”) to participants giving up as a result of disappointment (“resentful demoralization”). Without control of such reactions, trials may be vulnerable to performance bias (1). One leading trialist [18] has gone as far as to suggest that “the next substantive milestone in the history of efforts to create unbiased comparison groups may be erected when someone solves the interesting methodological conundrum presented by biases resulting from patient preferences”. Randomized controlled trials, like other research studies, involve interactions between participants and researchers. Patient preferences may have find more implications for the actual conduct of these studies, although trial design seeks to preclude this possibility, along with any impact on trial outcomes. This preliminary investigation explores how patient preferences may be associated with performance bias in one trial by examining reasons for participation and participant engagement with the research study. In so doing, it seeks to offer a participant-centered view of what it is like to become involved in a trial, in order to better appreciate the potential for biases that stem from research participation itself, which may not be well understood [19]. Case studies are investigations which pay particular attention to the contexts in which data are produced [20].