Decision to participate in cohort studies with biobanks:An empirical – ethical investigation

Introduction: Cohort studies with associated biobanks require participants’ sustained participation. To develop ethical and effective strategies for recruitment and retention, it is crucial to understand the factors involved in the decision to participate. Therefore, we aim to investigate participants’ decision to enrol in a cohort study with an associated biobank.

Methods: The present investigation includes: a systematic literature review, a qualitative semi-structured interview study, a cross-sectional survey and a secondary analysis of prospective data. Empirical studies were performed within two German cohort studies: the German National Cohort and the Potsdam Cohort of the European Investigation into Cancer and Nutrition.

Results: The literature review revealed that participants’ decision to enrol in biobank studies often equates to a cost-benefit analysis influenced by individual (e.g. attitudes) and contextual (e.g. family history of disease) elements. Perception of personal benefit in the form of health data and altruistic motivations appeared as the most commonly raised triggers for enrolment. Our qualitative investigation further characterized the decision to enrol as a complex interplay of factors belonging to different levels: individual (e.g. predispositions), institutional (e.g. reputation), study related (e.g. design), and societal (e.g. solidarity-driven). Different forms of trust appeared to pervade these various factors and crystalized as prerequisites for enrolment and sustained involvement in the study. Expectations of personal benefit in the form of health information were also found to be crucial in participants’ decisions to enrol. The personal benefit expected was sometimes exaggerated with respect to the information provided by the studies but did not indicate a misconception, rather a “diagnostic misestimation”. The survey data confirmed, to some extent, that the expectation of personal benefits was linked to the decision to enrol. It further highlighted the limited effectiveness of a recruitment frame precluding such direct benefit for participants. Our secondary data analysis unveiled associations between participants’ characteristics, i.e. low educational attainment, unhealthy lifestyle, and various forms of attrition over follow-up, i.e. non-response and withdrawal. Our data further showed that enrolment after reminding activities was associated with an increased chance of attrition during the follow-up period.

Discussion: Consideration of our two main findings, i.e. the crucial roles of trust and the expectation of personal benefit in the decision to enrol, unveils a certain tension between the principle of beneficence toward the participants and the duty to promote participants’ trust in research. Indeed, in the likely case that disproportioned expectations, i.e. diagnostic misestimations, are not met, they may eventually undermine participants’ trust in the research and the researchers. This tension at the ethical level is expected to have implications on the practical level regarding the participants’ long-term commitment to the study. To overcome this tension, we suggest reconsidering the public health nature of cohort studies with attached biobanks. Emphasizing research participation in a frame focused on the value of solidarity could indeed contribute to the promotion of adequate trust and the limitation of unrealistic expectations of benefit among participants.