[Therapy research in times of patient preference]

The Declaration of Helsinki bears the consequence that in the future reference-controlled clinical trials will increasingly replace placebo-controlled trials. This has enormous implications on research in complementary and alternative medicine: strong preferences for or against the compared therapies will prevent patients to consent to randomisation. In these circumstances a number of alternative designs have been proposed, based on the combination of preference and randomisation, but some of them suffer from severe methodological problems. Others are internally valid but unfeasible in practice and difficult to interpret. Thus, in case of strong patient preferences, we suggest to conduct non-randomised trials but to give special interest to advanced statistical methods (e.g. structural equation models) which must replace simple two-group comparisons.