Background: Recruitment to trials can be difficult. Despite careful planning and research outlining ways to improve recruitment, many trials do not achieve their target on time and require extensions of funding or time.
Methods: We describe a trial in which an internal pilot with embedded qualitative research was used to improve recruitment processes and inform recruitment projections for the main trial. At the end of the pilot, it was clear the sample size would not be met on time. Three steps were taken to optimise recruitment:
adjustments were made to the recruitment process using information from qualitative work done in the pilot and advice from a patient and public involvement group; work was undertaken to add more recruiting sites using site feasibility assessments; a projection equation was used to estimate recruitment at each site and overall trial recruitment.
Results: Qualitative work during the pilot phase allowed us to develop strategies to optimise recruitment during the main trial, which were incorporated into patient information, Standardised Operating Procedures and training sessions with recruiters. From our experience of feasibility assessments, we have developed a checklist of recommended considerations for feasibility assessments. For recruitment projections, we developed a 4-step projection equation to estimate the total number of cases to predict recruitment using a conversion rate of the number randomised divided by the number screened.
Conclusions: This work provides recommendations for feasibility assessments and an easy-to-use projection tool, which can be applied to other trials to help ensure a trial can reach the required sample size.
Trial registration: ISRCTN, ISRCTN92545361. Registered 6 September 2016, http://www.isrctn.com/ISRCTN92545361