The ethics of TwiCs, the second International Symposium


The Ethics of Trials within Cohorts (TwiCs) Designs: International Symposium took place in London on 7-8 Nov 2016 and included participants from UK, Canada, USA, and the Netherlands. TwiCs, formally called cmRCT (cohort multiple RCT) design, are beginning to be widely used around the world and the meeting discussed some of the current trials, issues that have arisen during the consent and randomisation process and shared experiences. The MHRA and HRA were also represented and are both supportive of this new design and are open to discussion for new studies. More than 20 studies have been set up since the design was first described in 2010 addressing questions in a variety of research fields including cancer, mental health, care of the elderly and rare diseases.

TwiCs are usually set up as a cohort, either disease specific or population-based receiving usual/standard care, with simple data collected at baseline and regular time points throughout follow-up. Participants from an eligible subgroup are then selected to be offered a new intervention and their outcome data is compared to those not selected from the same eligible subgroup (these thus acting as controls). There is usually a two-stage informed consent process with participants initially consenting to be part of the cohort, to the use of their data for the cohort and other studies and also for the research team to approach them about future interventions for which they are eligible. Only participants who are offered and consent to the new intervention receive the intervention. The initial cohort and the individual trials within the cohort will all have their own protocols, ethical approval and informed consent process. All participants will receive standard care unless they are invited and consent to receiving the interventions on offer. This therefore is closer to mimicking clinical practice, where patients are only consented to the interventions they receive. Data collection is simplified and all data is collected at regular intervals for all cohort participants, regardless of whether they are in an intervention group or not. The non-selected eligible participants from the cohort are used as controls for the new intervention. Multiple trials can be carried out in the same cohort.
There is ongoing research into the informed consent process and what level of consent is required for TwiCs, as well as into methodology underlying the design and analysis.

OCTRU is expecting to set up their first TwiC in 2017.

More information, a list of useful references and a list of some of the current TwiCs, are available from the website:

Professor David Torgerson, from York Trials Unit will be in Oxford giving a talk on this topic on the Friday 2nd Dec 2016 between 13:00-14:00 at the Botnar Research Centre - all are welcome to attend.