Using a Delphi survey to gain an international consensus on the challenges of conducting trials with adults with intellectual disabilities.

This is the first international survey exploring the experiences of researchers conducting randomised controlled trials with adults with intellectual disabilities. Many of the barriers and challenges reported can be overcome with creativity and some additional resources. Other challenges, including attitudes towards conducting trials with disabled populations, maybe harder to overcome. These findings have implications for conducting trials with other populations with cognitive or communication difficulties. Implications for disability researchers, funding bodies and ethical review panels are discussed.