Interventions to improve clinical trial recruitment with a focus on clinical staff from the recruiting site: a systematic review

Background Difficulties recruiting to clinical trials are well-documented. Strategies to engage staff from the clinical site where recruitment takes place may be helpful in increasing recruitment rates.Aim To systematically review the literature to evaluate the effectiveness of interventions that aim to increase recruitment to clinical trials, focused on clinical site staff who support recruitment.Methods A systematic search for randomised studies within a trial (SWATs) that aimed to improve recruitment to a randomised host trial in the field of health or social care aimed at clinical site staff was conducted. Studies were excluded if they aimed to increase retention, were targeted at participants, or the SWAT or host trial were non-randomised. Database and hand searches were conducted up to 25th July 2024. The primary outcome was the rate of recruitment. The Cochrane RoB2 tool was used to assess the risk of bias of included studies.Results A total of seven studies were retrieved; all had a high risk or some concerns of bias. Studies evaluated heterogenous interventions and were synthesised narratively. A digital training package for trainee principal investigators was the only intervention to demonstrate a statistically significant effect.Conclusion Due to the small number of studies retrieved and the heterogeneity between them, it was not possible to make any conclusions of effectiveness of any strategy at helping clinical site staff to recruit optimally. To prevent research waste, future SWATs need to focus on replications of recruitment interventions in populations and settings of need, rather than further single-study replications.Registration PROSPERO CRD42022346585.