Exploring qualitative methods reported in registered trials and their yields (EQUITY): systematic review

The reported use of qualitative methods in registered trials has increased over time and worldwide. They are reportedly more frequent in high-income countries and in trials of behavioural and other interventions. Trialists and other stakeholders need to recognise the benefits of using qualitative methods in surgical, device and drug trials, and trials conducted in poorer countries. Moreover, they should seriously consider using qualitative methods in these trials.