NESTED CONSENT DESIGN FOR CLINICAL-TRIALS

Background: Since random treatment allocation is hardly understood by the majority of patients, a new 'nested consent design' for clinical t rials is proposed. Proposed design: The design consists of a two-step enrollment of study subjects. The first step is the enrollment of part icipants into a follow-up study, where consent to be subjects involved in the follow-up is obtained. The second step is the enrollment of ra ndomly sampled eligible participants into a new treatment group. After the explanation of (1) treatment mode, (2) additional burdens associa ted with the proposed treatment and (3) expected effects and possible adverse events, written informed consent is obtained. Those who reject participation and those who are not allocated into the new treatment are treated by standard care. Endpoints are set to be the same for all follow-up study participants whether allocated into the new treatment or not, and follow-up is carried out in the same manner. Analyses are performed between those allocated to the new treatment and those non- allocated on an intent-to-treat basis. Example: Although not a clinica l trial, this design was applied in a smoking cessation program at Aic hi Cancer Center Hospital for fi rst-visit patients who answered in a question naire survey that they were smokers. Out of 1330 necessary pa rticipants, 324 were enrolled in the follow-up study during the first three months of enrollment. Conclusions: The design was found to be fe asible for prevention trials, and possibly for clinical trials to comp are a new treatment with a standard treatment. There seems to be no et hical difference between this design and the one-arm study design.