Making the case for completion bonuses in clinical trials.

Attrition is a serious problem in many clinical trials. The practice of offering completion bonuses-financial incentives offered to participants on the condition that they remain in a trial until they reach a prespecified study endpoint-is one means of addressing attrition. Despite their practical appeal, however, completion bonuses remain ethically controversial due to concern that they will coerce or unduly influence participants to not exercise their right to withdraw from a trial. Although this interaction with the right to withdraw does render completion bonuses conceptually distinct from other incentive payments offered to research participants, we argue here that completion bonuses are never coercive and, in the context of effective institutional review board oversight, are unlikely to be unduly influential. Nonetheless, because completion bonuses may in some cases still encourage unreasonable continued participation in a study, additional safeguards are appropriate. Rejecting completion bonuses entirely is, however, unnecessary and would problematically fail to address the significant ethical problems associated with participant attrition.