[Bias of results in clinical research due to method of informed consent]

Research ethics committees increasingly demand that investigators use an opt-in method (prior informed consent) to recruit their potential participants. Recent research has shown that opt-in systems of recruitment increase the response bias and reduce response rates. People willing to participate seem to find it burdensome to opt in. In contrast to this, public concern about an opt-out approach is minimal and will probably be outweighed by the potential harm caused by biased results from opt-in approaches. Concerns about protecting the rights of the individual should not override the importance of recruiting patients in medical research.