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Cited by 378Ethics in Clinical ResearchStatistical Methods in Clinical TrialsMeta-analysis and systematic reviews

Strategies to improve recruitment to randomised controlled trials

Open access
Treweek, Shaun, Mitchell, Elizabeth, Pitkethly, Marie, Cook, Jonathan, Kjeldstrøm, Monica, Johansen, Marit, Taskila, Taina K, Sullivan, Frank +4 more·2010·Cochrane Database of Systematic Reviews
DOI 10.1002/14651858.mr000013.pub5
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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 to improve recruitment of participants to randomised controlled trials. SEARCH STRATEGY: We searched the Cochrane Methodology Review Group Specialised Register - CMR (The Cochrane Library (online) Issue 1 2008) (searched 20 February 2008); MEDLINE, Ovid (1950 to date of search) (searched 06 May 2008); EMBASE, Ovid (1980 to date of search) (searched 16 May 2008); ERIC, CSA (1966 to date of search) (searched 19 March 2008); Science Citation Index Expanded, ISI Web of Science (1975 to date of search) (searched 19 March 2008); Social Sciences Citation Index, ISI Web of Science (1975 to date of search) (searched 19 March 2008); and National Research Register (online) (Issue 3 2007) (searched 03 September 2007); C2-SPECTR (searched 09 April 2008). We also searched PubMed (25 March 2008) to retrieve "related articles" for 15 studies included in a previous version of this review. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials of methods to increase recruitment to randomised controlled trials. This includes non-healthcare studies and studies recruiting to hypothetical trials. Studies aiming to increase response rates to questionnaires or trial retention, or which evaluated incentives and disincentives for clinicians to recruit patients were excluded. DATA COLLECTION AND ANALYSIS: Data were extracted 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 risk ratios and their 95% confidence intervals to describe the effects in individual trials, and assessed heterogeneity of these ratios between trials. MAIN 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 people recruiting participants. All studies were in health care. 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 (RR 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 effects of many other recruitment strategies are unclear; examples include the use of video to provide trial information to potential participants and modifying the training of recruiters. Many studies looked at recruitment to hypothetical trials and it is unclear how applicable these results are to real trials. AUTHORS' 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 because they also have disadvantages. For example, opt-out procedures are controversial and open designs are by definition unblinded.

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  • Methodological papers describe a wide range of factors that can contribute to recruitment success, including trial design and protocol development, selection of sites, staff engagement, realistic estimation of recruitment targets and study timeframe, enhanced participant contact and communication, financial incentive or compensation, and convenience and reduced participation burden.

    “Methodological papers describe a wide range of factors which can contribute to recruitment success, including trial design and protocol development, selection of sites, staff engagement, realistic estimation of recruitment targets and study timeframe, enhanced participant contact and communication, financial incentive or compensation and convenience and reduced participation burden [9, 10].”

    From Recruitment of low-income pregnant women into a dietary and dental care intervention: lessons from a feasibility trial (2020) · cites this paper as [9]

    The Types of interventions and Main results sections describe trial-design changes, recruiter-focused strategies, participant communication and monetary incentives as approaches to recruitment. The Background discusses missed targets and trial extensions, but the copy does not establish site selection, realistic target-setting and timeframes, or reduced participation burden as recruitment-success factors. It also finds the effects of many strategies unclear (Main results); page numbers were not available for these passages. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

  • Community engagement would be more important in ethnic minority recruitment, and less so in older peoples recruitment, as anticipated by the literature.

    “That community engagement would be more important in ethnic minority recruitment, and less so in older peoples recruitment, is anticipated by the literature [44,46,47],”

    From Development and evaluation of culturally sensitive psychosocial interventions for under-served people in primary care (2014) · cites this paper as [44]

    The section on modifying approaches to potential participants reports improved recruitment of African Americans with an enhanced package that included church sessions. It does not establish that community engagement matters more for ethnic minority recruitment than for older people's recruitment: the older-participant intervention was an educational package, not a community-engagement intervention. The Additional information section also says the review had not identified studies evaluating close collaborative relationships with potential participants in its initial search. Page numbers are not provided in our copy. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • Available evidence to support recruitment strategies is sparse.

    “However, available evidence to support recruitment strategies is sparse [44].”

    From Development and evaluation of culturally sensitive psychosocial interventions for under-served people in primary care (2014) · cites this paper as [44]

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3 of the 125 references couldn’t be matched to a known paper.

Research works printed but not linked: 2

  1. Higgins JPT, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in metaanalyses. BMJ 2003; 327: 557-560.
  2. Schulz KF, Chalmers I, Hayes RJ, Altman DG. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA 1995;273(5):408-12 Contributions to the protocol Contributing authors (October 2007):

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Authors
Treweek, S., Mitchell, E., Pitkethly, M., Cook, J., Kjeldstrøm, M., Johansen, M., Taskila, T. K., Sullivan, F., Wilson, S., Jackson, C., Jones, R., & Lockhart, P.
Affiliations
  • University of Dundee (GB)
  • University of Aberdeen (GB)
  • Nasjonalt Kunnskapssenter for Helsetjenesten (NO)
  • University of Birmingham (GB)
  • University of St Andrews (GB)
  • Nkhoma CCAP Hospital; P.O. Box 48 Malawi Malawi
ORCID
Venue
Cochrane Database of Systematic Reviews
Publisher
Wiley
Published
2010-04-14
Issue
4
Pages
MR000013-MR000013
ISSN
  • 1361-6137 (ISSN-L)
  • 1465-1858
DOI
10.1002/14651858.mr000013.pub5
OpenAlex
W2150229987
Cited by
378
References
125
Citations by year
2026: 4 · 2025: 4 · 2024: 5 · 2023: 7 · 2022: 11 · 2021: 13 · 2020: 19 · 2019: 21 · 2018: 36 · 2017: 36 · 2016: 33 · 2015: 32 · 2014: 47 · 2013: 41 · 2012: 32
FWCI
4.89
Type
journal article
Language
en
Update notices
new_version (2018-02-22)
Open access
Locations
  • Cochrane Database of Systematic Reviews (publishedVersion)
  • PubMed (publishedVersion)
  • Discovery Research Portal (University of Dundee) (submittedVersion, other-oa)
  • University of Birmingham Research Portal (University of Birmingham) (submittedVersion)
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, randomized controlled trials, health research participation, recruitment interventions, trial retention
MeSH terms
Humans, Patient Education as Topic, Randomized Controlled Trials as Topic, Sample Size, Patient Selection

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