Strategies to improve recruitment to randomised controlled trials

Poster
2010 Keystone
Cook J1, Treweek S2, Pitkethly M3, Kjeldstrøm M4, Taskila T5, Johansen M6, Sullivan F3, Wilson S5, Jackson C7, Jones R2, mitchell E2
1Health Services Research Unit, University of Aberdeen, Aberdeen, UK
2Division of Clinical & Population Sciences and Education, University of Dundee, Dundee, UK
3Centre for Primary Care and Population Research, University of Dundee, Dundee, UK
4Rigshospitalet, Nordic Cochrane Centre, Copenhagen, Denmark
5Department of Primary Care and General Practice, University of Birmingham, Birmingham, UK
6Nasjonalt kunnskapssenter for helsetjenesten, Norwegian Knowledge Centre for the Health Services, Oslo, Norway
7Community Health Sciences, University of Dundee, Dundee, UK
Background: Recruiting participants to trials can be extremely difficult. Identifying strategies that improve trial recruitment would benefit both trialists and health research. Objectives: To quantify the effects of strategies to improve recruitment of participants to randomised controlled trials. Methods: We searched the Cochrane Methodology Review Group Specialised Register (CMR), MEDLINE, EMBASE, ERIC, Science Citation Index Expanded, Social Sciences Citation Index, National Research Register, C2-SPECTR and PubMed. Randomised and quasi-randomised controlled trials of methods to increase recruitment to randomised controlled trials were included. Results: We identified 27 eligible trials with more than 26,604 participants. There were 24 studies involving interventions aimed directly at trial participants, while three evaluated interventions aimed at those recruiting participants. Some interventions were effective in increasing recruitment: telephone reminders to non-respondents (RR 2.66 95% CI 1.37 to 5.18), use of opt-out, rather than opt-in, procedures for contacting potential trial participants (RR 1.39 95% CI 1.06 to 1.84) and open designs where participants know which treatment they are receiving in the trial (1.25 95% CI 1.18 to 1.34). However, some of these strategies have disadvantages, which may limit their widespread use. For example, opt-out procedures are controversial and open designs are by definition unblinded. The effect of many other recruitment strategies is unclear; for example the use of video to provide trial information to potential participants. Many studies looked at recruitment to hypothetical trials; the applicability of such to real trials is unclear. Conclusions: Trialists can increase recruitment to their trials by using the strategies shown to be effective in this review: telephone reminders, use of opt-out, rather than opt-in, procedures for contacting potential trial participants and open designs. Some strategies (e.g. open trial designs) need to be considered carefully before use since they also have disadvantages.