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Cited by 521Ethics in Clinical ResearchStatistical Methods in Clinical TrialsMeta-analysis and systematic reviews

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Strategies to improve recruitment to randomised trials

Open access
Treweek, Shaun, Pitkethly, Marie, Cook, Jonathan, Fraser, Cynthia, Mitchell, Elizabeth, Sullivan, Frank, Jackson, Catherine, Taskila, Tyna K, Gardner, Heidi·2018·Cochrane Database of Systematic Reviews
DOI 10.1002/14651858.mr000013.pub6PMC PMC7078793
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Abstract

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 for improving recruitment of participants to randomised trials. A secondary objective is to assess the evidence for the effect of the research setting (e.g. primary care versus secondary care) on recruitment. SEARCH METHODS: We searched the Cochrane Methodology Review Group Specialised Register (CMR) in the Cochrane Library (July 2012, searched 11 February 2015); MEDLINE and MEDLINE In Process (OVID) (1946 to 10 February 2015); Embase (OVID) (1996 to 2015 Week 06); Science Citation Index & Social Science Citation Index (ISI) (2009 to 11 February 2015) and ERIC (EBSCO) (2009 to 11 February 2015). SELECTION CRITERIA: Randomised and quasi-randomised trials of methods to increase recruitment to randomised trials. This includes non-healthcare studies and studies recruiting to hypothetical trials. We excluded studies aiming to increase response rates to questionnaires or trial retention and those evaluating incentives and disincentives for clinicians to recruit participants. DATA COLLECTION AND ANALYSIS: We extracted data on: the method evaluated; country in which the study was carried out; nature of the population; nature of the study setting; nature of the study to be recruited into; randomisation or quasi-randomisation method; and numbers and proportions in each intervention group. We used a risk difference to estimate the absolute improvement and the 95% confidence interval (CI) to describe the effect in individual trials. We assessed heterogeneity between trial results. We used GRADE to judge the certainty we had in the evidence coming from each comparison. MAIN RESULTS: We identified 68 eligible trials (24 new to this update) with more than 74,000 participants. There were 63 studies involving interventions aimed directly at trial participants, while five evaluated interventions aimed at people recruiting participants. All studies were in health care.We found 72 comparisons, but just three are supported by high-certainty evidence according to GRADE.1. Open trials rather than blinded, placebo trials. The absolute improvement was 10% (95% CI 7% to 13%).2. Telephone reminders to people who do not respond to a postal invitation. The absolute improvement was 6% (95% CI 3% to 9%). This result applies to trials that have low underlying recruitment. We are less certain for trials that start out with moderately good recruitment (i.e. over 10%).3. Using a particular, bespoke, user-testing approach to develop participant information leaflets. This method involved spending a lot of time working with the target population for recruitment to decide on the content, format and appearance of the participant information leaflet. This made little or no difference to recruitment: absolute improvement was 1% (95% CI -1% to 3%).We had moderate-certainty evidence for eight other comparisons; our confidence was reduced for most of these because the results came from a single study. Three of the methods were changes to trial management, three were changes to how potential participants received information, one was aimed at recruiters, and the last was a test of financial incentives. All of these comparisons would benefit from other researchers replicating the evaluation. There were no evaluations in paediatric trials.We had much less confidence in the other 61 comparisons because the studies had design flaws, were single studies, had very uncertain results or were hypothetical (mock) trials rather than real ones. AUTHORS' CONCLUSIONS: The literature on interventions to improve recruitment to trials has plenty of variety but little depth. Only 3 of 72 comparisons are supported by high-certainty evidence according to GRADE: having an open trial and using telephone reminders to non-responders to postal interventions both increase recruitment; a specialised way of developing participant information leaflets had little or no effect. The methodology research community should improve the evidence base by replicating evaluations of existing strategies, rather than developing and testing new ones.

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Research works printed but not linked: 18

  1. Jennings, 2015, Does offering an incentive payment improve recruitment to clinical trials and increase the proportion of socially deprived and elderly participants?, Trials, 16, 80, 10.1186/s13063-015-0582-8 · DOI
  2. Jennings, 2015, Does offering an incentive payment improve recruitment to clinical trials and increase the proportion of socially deprived and elderly participants?, Trials, 16, 80, 10.1186/s13063-015-0582-8 · DOI
  3. Jennings, 2015, Does offering an incentive payment improve recruitment to clinical trials and increase the proportion of socially deprived and elderly participants?, Trials, 16, 80, 10.1186/s13063-015-0582-8 · DOI
  4. Jennings, 2015, Does offering an incentive payment improve recruitment to clinical trials and increase the proportion of socially deprived and elderly participants?, Trials, 16, 80, 10.1186/s13063-015-0582-8 · DOI
  5. Man, 2015, Improving recruitment to a study of telehealth management for long-term conditions in primary care: two embedded, randomised controlled trials of optimised patient information materials, Trials, 16, 309, 10.1186/s13063-015-0820-0 · DOI
  6. Perrone, 1995, Looking for consent in RCTs: a randomised trial with surrogate patients, Epidemiologia e Prevenzione, 19, 282
  7. Brocklehurst P Tarnow-Mordi W Farrell B Quigley M INLET trial - cluster trial of newsletters and educational supplements to centres participating in INIS trial Oxford: National Perinatal Epidemiology Unit; 2007. Annual Report 2006
  8. Calimlim, 1977, Selection, attrition, and consent in recruitment of patients for a clinical trial, Clinical Pharmacology & Therapeutics, 21, 100
  9. Donovan, 2010, Development and application of a complex intervention to improve recruitment to randomised controlled trials, Clinical Trials, 7, 469
  10. Eckardt, 2011, Impact of direct physician-to-physician contact on accelerating oncology clinical trials accrual, Journal of Clinical Oncology, 29
  11. Feman, 2008, Effectiveness of recruitment in clinical trials: an analysis of methods used in a trial for irritable bowel syndrome patients, Contemporary Clinical Trials, 29, 241, 10.1016/j.cct.2007.08.004 · DOI
  12. Gillan, 2009, Increasing participant recruitment into large-scale screening trials: experience from the CADET II study, Journal of Medical Screening, 16, 180, 10.1258/jms.2009.009023 · DOI
  13. Menoyo E Perez M de la Torre R Farré M Telephone screening to improve recruitment of healthy volunteers in neuropsychopharmacology clinical trials: role of nurses Proceedings of the 20th Congress of the Spanish Clinical Pharmacology Society 2006
  14. Monane, 1991, The randomized controlled trial in the long-term care setting - recruitment and enrollment, Journal of the American Geriatrics Society, 39, A51
  15. Porucznik, 2010, Participant recruitment in a virtually interconnected world: comparative effectiveness and considerations of bias, American Journal of Epidemiology, 171, s147
  16. Quinaux, 2003, Impact of monitoring visits on patient recruitment and data quality: case study of a phase IV trial in oncology, Controlled Clinical Trials, 24, 99S
  17. Saul, 2002, Influences on recruitment in clinical trials, European Journal of Cancer, 38, 2334
  18. Greenlee, 2003, Recruitment feasibility for a pilot randomized controlled trial on the effect of naturopathic therapies on estrogen metabolism, Cancer Epidemiology Biomarkers & Prevention, 12, 1302s

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Metadata

Authors
Treweek, S., Pitkethly, M., Cook, J., Fraser, C., Mitchell, E., Sullivan, F., Jackson, C., Taskila, T. K., & Gardner, H.
Affiliations
  • University of Aberdeen (GB)
  • University of Dundee (GB)
  • Nuffield Orthopaedic Centre (GB)
  • University of Hull (GB)
  • University of St Andrews (GB)
  • University of Lancashire (GB)
  • The Work Foundation (GB)
ORCID
Venue
Cochrane Database of Systematic Reviews
Publisher
Wiley
Published
2018-02-22
Volume
2018
Issue
2
Pages
MR000013-MR000013
ISSN
  • 1361-6137 (ISSN-L)
  • 1465-1858
DOI
10.1002/14651858.mr000013.pub6
PMC
PMC7078793
OpenAlex
W2788630491
Cited by
521
References
185
Citations by year
2026: 31 · 2025: 61 · 2024: 75 · 2023: 81 · 2022: 75 · 2021: 83 · 2020: 70 · 2019: 35 · 2018: 9
FWCI
8.99
Type
journal article
Language
en
Update notices
new_version (2026-09-15)
Open access
Locations
  • Cochrane Database of Systematic Reviews (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • CLOK (University of Central Lancashire) (acceptedVersion)
  • Aberdeen University Research Archive (Aberdeen University) (submittedVersion)
  • St Andrews Research Repository (St Andrews Research Repository) (submittedVersion)
Funders
  • National Institute for Health and Care Research (NF-SI-0514-10114)
  • Medical Research Council (MR/K025643/1)
Topics
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Ethics in Clinical Research
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
Keywords
trial recruitment, participant recruitment strategies, randomised trials, telephone reminders, recruitment incentives, primary care, secondary care, research settings, trial retention
MeSH terms
Humans, Patient Education as Topic, Telephone, Randomized Controlled Trials as Topic, Reminder Systems, Sample Size, Patient Selection

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