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. 2018 Feb 22;2(2):MR000013.
doi: 10.1002/14651858.MR000013.pub6.

Strategies to improve recruitment to randomised trials

Shaun Treweek  1 , Marie Pitkethly, Jonathan Cook, Cynthia Fraser, Elizabeth Mitchell, Frank Sullivan, Catherine Jackson, Tyna K Taskila, Heidi Gardner
Affiliations

Strategies to improve recruitment to randomised trials

Shaun Treweek et al. Cochrane Database Syst Rev. .

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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Conflict of interest statement

Shaun Treweek and Frank Sullivan are coauthors of Treweek 2012; they were not involved in data extraction or risk of bias assessment for this study for this review. Although Shaun Treweek was not involved in Cockayne 2017, he was involved in the wider START study in which Cockayne 2017 was nested; he was not involved in data extraction or risk of bias assessment for this study for this review. Shaun Treweek was a reviewer for Jennings 2015a; Jennings 2015b; Jennings 2015c; Jennings 2015d; Jennings 2015e (all included in a single article). Shaun Treweek and Frank Sullivan declare no further conflict of interest.

Marie Pitkethly: none known.

Jonathan Cook: none known.

Cynthia Fraser: none known.

Elizabeth Mitchell: none known.

Catherine Jackson: none known.

Tyna Taskila: none known.

Heidi Gardner: none known.

Figures

1
1
'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
2
2
'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study.
1.1
1.1. Analysis
Comparison 1 A–Open trial vs blinded trial (GRADE: high), Outcome 1 Participants recruited.
2.1
2.1. Analysis
Comparison 2 A–Patient preference design vs conventional RCT (GRADE: low), Outcome 1 Participants recruited.
3.1
3.1. Analysis
Comparison 3 A–Electronic data capture vs paper‐based data capture (GRADE: low), Outcome 1 Participants recruited.
4.1
4.1. Analysis
Comparison 4 A–Placebo vs other comparator (high risk of bias; hypothetical), Outcome 1 Participants recruited.
5.1
5.1. Analysis
Comparison 5 A–Video describing response‐adaptive design vs video describing standard design (high risk of bias; hypothetical), Outcome 1 Participants recruited.
6.1
6.1. Analysis
Comparison 6 C–Telephone reminder vs no telephone reminder (GRADE: high), Outcome 1 Participants recruited.
7.1
7.1. Analysis
Comparison 7 C–SMS reminder mentioning scarcity vs SMS reminder with no mention (GRADE: moderate), Outcome 1 Participants recruited.
8.1
8.1. Analysis
Comparison 8 C–SMS messages containing quotes from existing participants vs no messages (GRADE: moderate), Outcome 1 Participants recruited.
9.1
9.1. Analysis
Comparison 9 C–Email invitation vs postal invitation (GRADE: moderate), Outcome 1 Participants recruited.
10.1
10.1. Analysis
Comparison 10 C–Telephone screening vs face‐to‐face screening (high risk of bias), Outcome 1 Participants recruited.
11.1
11.1. Analysis
Comparison 11 C–Screening by senior investigator vs screening by research assistant (high risk of bias), Outcome 1 Participants recruited.
12.1
12.1. Analysis
Comparison 12 C–Tablet computer to support screening vs voice response system to support screening (high risk of bias), Outcome 1 Willingness to take part if eligible.
13.1
13.1. Analysis
Comparison 13 C–Electronic completion of screening questionnaire vs standard paper completion (high risk of bias; hypothetical), Outcome 1 Participants recruited.
14.1
14.1. Analysis
Comparison 14 C–Oral completion of screening questionnaire vs standard paper completion (high risk of bias; hypothetical), Outcome 1 Participants recruited.
15.1
15.1. Analysis
Comparison 15 D–Opt‐out consent vs opt‐in consent (GRADE: low), Outcome 1 Participants recruited.
16.1
16.1. Analysis
Comparison 16 D–Consent to experimental care vs usual consent (GRADE: very low), Outcome 1 Participants recruited.
17.1
17.1. Analysis
Comparison 17 D–Consent to standard care vs usual consent (GRADE: very low), Outcome 1 Participants recruited.
18.1
18.1. Analysis
Comparison 18 D–Researcher reading out consent vs participant reading consent (unclear risk of bias), Outcome 1 Participants recruited.
19.1
19.1. Analysis
Comparison 19 D–Information printed on heavyweight paper and blue folio vs standard (high risk of bias), Outcome 1 Participants recruited.
20.1
20.1. Analysis
Comparison 20 D–Refusers choose treatment vs usual consent (high risk of bias; hypothetical), Outcome 1 Participants recruited.
21.1
21.1. Analysis
Comparison 21 D–Physician‐modified consent vs usual consent (high risk of bias; hypothetical), Outcome 1 Participants recruited.
22.1
22.1. Analysis
Comparison 22 D–Participant‐modified consent vs usual consent (high risk of bias; hypothetical), Outcome 1 Participants recruited.
23.1
23.1. Analysis
Comparison 23 D–Implicit participant values clarification task vs standard consent procedure (high risk of bias; hypothetical), Outcome 1 Participants recruited.
24.1
24.1. Analysis
Comparison 24 D–Explicit participant values clarification task vs standard (high risk of bias; hypothetical), Outcome 1 Participants recruited.
25.1
25.1. Analysis
Comparison 25 E–Bespoke, user‐tested PIL vs usual PIL (GRADE: moderate), Outcome 1 Participants recruited.
26.1
26.1. Analysis
Comparison 26 E–Brief participant information leaflet (PIL) vs full PIL (GRADE: moderate), Outcome 1 Participants recruited.
27.1
27.1. Analysis
Comparison 27 E–Study‐related questionnaire + trial invitation vs trial invitation (GRADE: moderate), Outcome 1 Participants recruited.
28.1
28.1. Analysis
Comparison 28 E–PIL developed with feedback from users vs usual PIL (GRADE: moderate), Outcome 1 Participants recruited.
29.1
29.1. Analysis
Comparison 29 E–Recruitment primer letter vs no letter (GRADE: low), Outcome 1 Participants recruited.
30.1
30.1. Analysis
Comparison 30 E–Information provided over telephone vs information provided face‐to‐face (GRADE: low), Outcome 1 Participants recruited.
31.1
31.1. Analysis
Comparison 31 E–Enhanced recruitment package + recruitment at churches vs standard recruitment package (GRADE: low), Outcome 1 Participants recruited.
32.1
32.1. Analysis
Comparison 32 E–Enhanced recruitment package vs standard recruitment package (GRADE: low), Outcome 1 Participants recruited.
33.1
33.1. Analysis
Comparison 33 E–Enhanced recruitment package + baseline data over telephone vs standard recruitment package (GRADE: low), Outcome 1 Participants recruited.
34.1
34.1. Analysis
Comparison 34 E–Emphasising risk in information vs standard information (GRADE: low), Outcome 1 Participants recruited.
35.1
35.1. Analysis
Comparison 35 E–Wording treatment effect as 'twice as fast' in trial information vs writing 'half as fast' (GRADE: low), Outcome 1 Participants recruited.
36.1
36.1. Analysis
Comparison 36 E–Emphasising pain in information vs standard information (GRADE: low), Outcome 1 Participants recruited.
37.1
37.1. Analysis
Comparison 37 E–Providing information by video vs standard information (GRADE: very low), Outcome 1 Participants recruited.
38.1
38.1. Analysis
Comparison 38 E–Audio record of information given about trial vs no audio record (GRADE: very low), Outcome 1 Participants recruited.
39.1
39.1. Analysis
Comparison 39 E–Clinical trial booklet + standard information vs standard information (GRADE: very low), Outcome 1 Participants recruited.
40.1
40.1. Analysis
Comparison 40 E–Total information disclosure vs standard disclosure (GRADE: very low), Outcome 1 Participants recruited.
41.1
41.1. Analysis
Comparison 41 E–Newspaper article + study information vs study information only (high risk of bias), Outcome 1 Participants recruited.
42.1
42.1. Analysis
Comparison 42 E–Interactive computer presentation of trial information vs standard paper presentations (high risk of bias), Outcome 1 Participants recruited.
43.1
43.1. Analysis
Comparison 43 E–Access to cancer trials website vs no access (high risk of bias), Outcome 1 Participants recruited.
44.1
44.1. Analysis
Comparison 44 E–More favourable newspaper article + study information vs less favourable newspaper article + study information (high risk of bias), Outcome 1 Participants recruited.
45.1
45.1. Analysis
Comparison 45 E‐Clinical trial booklet + standard information vs standard information (high risk of bias; hypothetical), Outcome 1 Participants recruited.
46.1
46.1. Analysis
Comparison 46 E–Educational audiovisual information + help vs standard information + general audiovisual information + help (high risk of bias; hypothetical), Outcome 1 Participants recruited.
47.1
47.1. Analysis
Comparison 47 E–Educational audiovisual information + written information vs written information (high risk of bias; hypothetical), Outcome 1 Participants recruited.
48.1
48.1. Analysis
Comparison 48 E–Negative framing of side effects vs neutral framing (high risk of bias; hypothetical), Outcome 1 Participants recruited.
49.1
49.1. Analysis
Comparison 49 E–Positive framing of side effects vs neutral framing (high risk of bias; hypothetical), Outcome 1 Participants recruited.
50.1
50.1. Analysis
Comparison 50 E–Less detailed presentation of risk and other information vs more detailed presentation (high risk of bias; hypothetical), Outcome 1 Participants recruited.
51.1
51.1. Analysis
Comparison 51 E–Information leaflet with explanation vs information leaflet without explanation (high risk of bias; hypothetical), Outcome 1 Participants recruited.
52.1
52.1. Analysis
Comparison 52 E–Brief counselling + print materials vs print alone (high risk of bias; hypothetical), Outcome 1 Participants recruited.
53.1
53.1. Analysis
Comparison 53 E–Interactive computer presentation of trial information vs audio‐taped presentation (high risk of bias; hypothetical), Outcome 1 Participants recruited.
54.1
54.1. Analysis
Comparison 54 E–One new vs both standard (intervention description) (high risk of bias; hypothetical), Outcome 1 Participants recruited.
55.1
55.1. Analysis
Comparison 55 F–Teaser campaign using postcards vs no teaser (GRADE: moderate), Outcome 1 Primary care centre recruited.
56.1
56.1. Analysis
Comparison 56 F–Doctor knows patient preferences about participation vs standard (high risk of bias), Outcome 1 Participants recruited.
57.1
57.1. Analysis
Comparison 57 G‐Financial incentive vs no incentive (GRADE: moderate), Outcome 1 Participants recruited.
See this image and copyright information in PMC

Update of

Comment in

References

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Nystuen 2004 {published data only}
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Paul 2011 {published data only}
    1. Paul J, Iveson T, Midgely R, Harkin A, Masterton M, Alexander L, Cassidy J. Choice of randomisation time‐point in non‐inferiority studies of reduced treatment duration: experience from the SCOT study. Trials 2011;12:A30.
Paul 2014 {published data only}
    1. Paul C, Courtney R, Sanson‐Fisher R, Carey M, Hill D, Simmons J, Rose S. A randomized controlled trial of the effectiveness of a pre‐recruitment primer letter to increase participation in a study of colorectal screening and surveillance. BMC Medical Research Methodology 2014;14:44. [DOI: 10.1186/1471-2288-14-44] - DOI - PMC - PubMed
Perrone 1995 {published data only}
    1. Perrone F, Placido S, Giusti C, Gallo C. Looking for consent in RCTs: a randomised trial with surrogate patients [La richiesta del consenso nella ricerca clinica: uno studio randomizzato in soggetti sani]. Epidemiologia e Prevenzione 1995;19:282‐90. - PubMed
Pighills 2009 {published data only}
    1. Pighills A, Torgerson DJ, Sheldon T. Publicity does not increase recruitment to falls prevention trials: the results of two quasi‐randomized trials. Journal of Clinical Epidemiology 2009;62:1332‐5. - PubMed
Simel 1991 {published data only}
    1. Simel DL, Feussner JR. A randomized controlled trial comparing quantitative informed consent formats. Journal of Clinical Epidemiology 1991;44(8):771‐7. - PubMed
Simes 1986 {published data only}
    1. Simes RJ, Tattersall MHN, Coates AS, Raghavan D, Solomon HJ. Randomised comparison of procedures for obtaining informed consent in clinical trials of treatment for cancer. BMJ 1986;293:1065‐8. - PMC - PubMed
Tehranisa 2014 {published data only}
    1. Tehranisa JS, Meurer WJ. Can response‐adaptive randomization increase participation in acute stroke trials?. Stroke 2014;45:2131‐3. [DOI: 10.1161/STROKEAHA.114.005418] - DOI - PMC - PubMed
Tilley 2012 {published data only}
    1. Tilley BC, Mainous AG, Elm JJ, Pickelsimer E, Soderstrom LH, Ford ME, et al. A randomized recruitment intervention trial in Parkinson's disease to increase participant diversity: early stopping for lack of efficacy. Clinical Trials 2012;9:188‐97. - PMC - PubMed
Treschan 2003 {published data only}
    1. Treschan TA, Scheck T, Kober A, Fleischmann E, Birkenberg B, Petschnigg B, et al. The influence of protocol pain and risk on patients' willingness to consent for clinical studies: a randomized trial. Economics, Education, and Health Systems Research 2003;96:498‐506. - PubMed
Trevena 2006 {published data only}
    1. Trevena L, Irwig L, Barratt A. Impact of privacy legislation on the number and characteristics of people who are recruited for research: a randomised controlled trial. Journal of Medical Ethics 2006;32:473‐7. - PMC - PubMed
Treweek 2012 {published data only}
    1. Treweek S, Barnett K, Maclennan G, Bonetti D, Eccles MP, Francis JJ, et al. E‐mail invitations to general practitioners were as effective as postal invitations and were more efficient. Journal of Clinical Epidemiology 2012;65:793‐7. [DOI: 10.1016/j.jclinepi.2011.11.010] - DOI - PubMed
Wadland 1990 {published data only}
    1. Wadland WC, Hughes JR, Secker‐Walker RH, Bronson DL, Fenwick J. Recruitment in a primary care trial on smoking cessation. Family Medicine 1990;22:201‐4. - PubMed
Weinfurt 2008a {published data only}
    1. Weinfurt KP, Hall MA, Friedman JY, Hardy NC, Fortune‐Greeley AK, Lawlor JS, et al. Effects of disclosing financial interests on participation in medical research: a randomized vignette trial. Journal of General Internal Medicine 2008;23:860‐6. - PMC - PubMed
Weinfurt 2008b {published data only}
    1. Weinfurt KP, Hall MA, Friedman JY, Hardy NC, Fortune‐Greeley AK, Lawlor JS, et al. Effects of disclosing financial interests on participation in medical research: a randomized vignette trial. American Heart Journal 2008;156:689‐97. - PMC - PubMed
Wells 2013 {published data only}
    1. Wells KJ, McIntyre J, Gonzalez LE, Lee JH, Fisher KJ, Jacobsen PB. Feasibility trial of a Spanish‐language multimedia educational intervention. Clinical Trials 2013;10:767‐74. - PMC - PubMed
Welton 1999 {published data only}
    1. Welton AJ, Vickers MR, Cooper JA, Meade TW, Marteau TM. Is recruitment more difficult with a placebo arm in randomised controlled trials? A quasi randomised, interview based study. BMJ 1991;318:1114‐7. - PMC - PubMed
Weston 1997 {published data only}
    1. Weston J, Hannah M, Downes J. Evaluating the benefits of a patient information video during the informed consent process. Patient Education and Counseling 1997;30:239‐45. - PubMed
Wong 2013 {published data only}
    1. Wong AD, Kirby J, Guyatt GH, Moayyedi P, Vora P, You JJ. Randomized controlled trial comparing telephone and mail follow‐up for recruitment of participants into a clinical trial of colorectal cancer screening. Trials 2013;14:40. [DOI: 10.1186/1745-6215-14-40] - DOI - PMC - PubMed

References to studies excluded from this review

Aalborg 2012 {published data only}
    1. Aalborg AE, Miller BA, Husson G, Byrnes HF, Bauman KE, Spoth RL. Implementation of adolescent family‐based substance use prevention programs in health care settings: comparisons across conditions and programs. Health Education Journal 2012;71:53‐61. [DOI: 10.1177/0017896910386209] - DOI - PMC - PubMed
Aaronson 1996 {published data only}
    1. Aaronson NK, Visser‐Pol E, Gerleen HMW, Muller MJ, Schot AC, Dam FS, et al. Telephone‐based nursing intervention improves the effectiveness of the informed consent process in cancer clinical trials. Journal of Clinical Oncology 1996;14:984‐96. - PubMed
Agoritsas 2010 {published data only}
    1. Agoritsas T, Deom M, Perneger TV. Study design attributes influenced patients' willingness to participate in clinical research: a randomized vignette‐based study. Journal of Clinical Epidemiology 2011;64:107‐15. [DOI: ] - PubMed
Alexander 2008 {published data only}
    1. Alexander GL, Divine GW, Couper MP, McClure JB, Stopponi MA, Fortman KK, et al. Effect of incentives and mailing features on online health program enrollment. American Journal of Preventive Medicine 2008;34:382‐8. - PMC - PubMed
Andrew 1993 {published data only}
    1. Andrew M, Vegh P, Caco C, Kirpalani H, Jefferies A, Ohlsson A, et al. A randomized, controlled trial of platelet transfusions in thrombocytopenic premature infants. Journal of Pediatrics 2003;123:285‐91. - PubMed
Barnard 2010 {published data only}
    1. Barnard KD, Dent L, Cook A. A systematic review of models to predict recruitment to multicentre clinical trials. BMC Medical Research Methodology 2011;10:63. [DOI: 10.1186/1471-2288-10-63] - DOI - PMC - PubMed
Berman 2005 {published data only}
    1. Berman SR, Friedman EC, Callan JO, Fasiczka AL, McLean M, Hunter DM, et al. Recruitment and screening strategies for bipolar clinical trials. Bipolar Disorders 2005;7(Suppl 2):27‐117.
Brach 2013 {published data only}
    1. Brach M, Moschny A, Bücker B, Klaaßen‐Mielke R, Trampisch M, Wilm S, et al. Recruiting hard‐to‐reach subjects for exercise interventions: a multi‐centre and multi‐stage approach targeting general practitioners and their community‐dwelling and mobility‐limited patients. International Journal of Environmental Research and Public Health 2013;10:6611‐29. [DOI: 10.3390/ijerph10126611] - DOI - PMC - PubMed
Brealey 2007 {published data only}
    1. Brealey SD, Atwell C, Bryan S, Coulton S, Cox H, Cross B, et al. Using postal randomization to replace telephone randomization had no significant effect on recruitment of patients. Journal of Clinical Epidemiology 2006;60:1046‐51. - PubMed
Breland‐Noble 2012 {published data only}
    1. Breland‐Noble AM, AAKOMA Project Adult Advisory Board. Community and treatment engagement for depressed African American youth: the AAKOMA FLOA pilot. Journal of Clinical Psychology in Medical Settings 2012;19:41‐8. [DOI: 10.1007/s10880-011-9281-0] - DOI - PubMed
Brocklehurst 2007 {published data only}
    1. 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.
Brown 2012 {published data only}
    1. Brown SD, Lee K, Schoffman DE, King AC, Crawley LM, Kiernan M, et al. Minority recruitment into clinical trials: experimental findings and practical implications. Contempary Clinical Trials 2012;33:620‐3. [DOI: 10.1016/j.cct.2012.03.003] - DOI - PMC - PubMed
Burns 2008 {published data only}
    1. Burns D, Soward AC, Skelly AH, Leeman J, Carlson J. Effective recruitment and retention strategies for older members of rural minorities. Diabetes Educator 2008;34:1045‐52. - PubMed
Caldwell 2002 {published data only}
    1. Caldwell P, Craig J, Hamilton S. [Strategies for recruitment to RCTs: a systematic review of controlled trials and observational studies]. International Clinical Trials Symposium: improving health care in the new millennium, 2002 October 21‐23; Sydney. 2002:34‐5.
Calimlim 1977 {published data only}
    1. Calimlim J, Wardell WM, Lasagna L. Selection, attrition, and consent in recruitment of patients for a clinical trial. Clinical Pharmacology & Therapeutics 1977;21:100.
Carney 2014 {published data only}
    1. Carney PA, Tucker EK, Newby TA, Beer TM. Feasibility, acceptability and findings from a pilot randomized controlled intervention study on the impact of a book designed to inform patients about cancer clinical trials. Journal of Cancer Education 2014;29(1):181‐7. [DOI: 10.1007/s13187-013-0567-9] - DOI - PMC - PubMed
Celentano 1995 {published data only}
    1. Celentano DD, Beyrer C, Natpratan C, Eiumtrakul S, Sussman L, Renzullo PO, et al. Willingness to participate in AIDS vaccine trials among high‐risk populations in northern Thailand. AIDS 1995;9:1079‐83. - PubMed
Chin Feman 2008 {published data only}
    1. Chin Feman SP, Nguyen LT, Quilty MT, Kerr CE, Nam BH, Conboy LA, et al. Effectiveness of recruitment in clinical trials: an analysis of methods used in a trial for irritable bowel syndrome patients. Contemporary Clinical Trials 2008;29:241‐51. - PMC - PubMed
Chlebowski 2010 {published data only}
    1. Chlebowski RT, Menon R, Chaisanguanthum RM, Jackson DM. Prospective evaluation of two recruitment strategies for a randomized controlled cancer prevention trial. Clinical Trials 2010;7:744‐8. [DOI: 10.1177/1740774510383886] - DOI - PubMed
Clagett 2013 {published data only}
    1. Clagett B, Nathanson KL, Ciosek SL, McDermoth M, Vaughn DJ, Mitra N, et al. Comparison of address‐based sampling and random‐digit dialing methods for recruiting young men as controls in a case‐control study of testicular cancer susceptibility. American Journal of Epidemiology 2013;178(11):1638‐47. [DOI: 10.1093/aje/kwt164] - DOI - PMC - PubMed
Cook 2010 {published data only}
    1. Cook ED, Arnold KB, Hermos JA, McCaskill‐Stevens W, Moody‐Thomas S, Probstfield JL, et al. Impact of supplemental site grants to increase African American accrual for the Selenium and Vitamin E Cancer Prevention Trial. Clinical Trials 2010;7(1):90‐9. [DOI: 10.1177/1740774509357227] - DOI - PMC - PubMed
Coronado 2012 {published data only}
    1. Coronado GD, Ondelacy S, Schwarz Y, Duggan C, Lampe JW, Neuhouser ML. Recruiting underrepresented groups into the Carbohydrates and Related Biomarkers (CARB) cancer prevention feeding study. Contemporary Clinical Trials 2012;33(4):641‐6. [DOI: 10.1016/j.cct.2012.03.017] - DOI - PMC - PubMed
Dal‐Ré 1991 {published data only}
    1. Dal‐Ré R. Clinical research with drugs: a study of the influence of information about adverse reactions on obtaining informed consent [Investigación clínica con fármacos: estudio de la influencia de la informacíon sobre reacciones adversas en la obtención del consentimiento informado]. Medicina Clínica (Barcelona) 1991;96:566‐9. - PubMed
Davis 1998 {published data only}
    1. Davis TC, Holcombe RF, Berkel HJ, Pramanik S, Divers SG. Informed consent for clinical trials: a comparative study of standard versus simplified forms. Journal of the National Cancer Institute 1998;90:668‐74. - PubMed
Donovan 2009 {published data only}
    1. Donovan J, Lane JA, Peters TJ, Brindle L, Salter E, Gillatt D, et al. Development of a complex intervention improved randomization and informed consent in a randomized controlled trial. Journal of Clinical Epidemiology 2009;62:29‐36. - PubMed
Donovan 2010 {published data only}
    1. Donovan J, Lane A, Mills N, Neal D, Hamdy F, the ProtecT Study Group. Development and application of a complex intervention to improve recruitment to randomised controlled trials. Clinical Trials 2010;7:469.
Eckardt 2011 {published data only}
    1. Eckardt JR, DeMaggio AW, Peracha O, Levonyak M, Ku N. Impact of direct physician‐to‐physician contact on accelerating oncology clinical trials accrual. Journal of Clinical Oncology 2011;29(15 Suppl).
Embi 2012 {published data only}
    1. Embi PJ, Leonard AC. Evaluating alert fatigue over time to EHR‐based clinical trial alerts: findings from a randomized controlled study. Journal of the American Medical Informatics Association: JAMIA 2012;19:145‐8. [DOI: 10.1136/amiajnl-2011-000743] - DOI - PMC - PubMed
Enama 2012 {published data only}
    1. Enama ME, Hu Z, Gordon I, Costner P, Ledgerwood JE, Grady C, VRC 306 and 307 Consent Study Teams. Randomization to standard and concise informed consent forms: development of evidence‐based consent practices. Contemporary Clinical Trials 2012;33(5):895‐902. [DOI: 10.1016/j.cct.2012.04.005] - DOI - PMC - PubMed
Feman 2008 {published data only}
    1. Feman SPC, Nguyen LI, Quilty MT, Kerr CE, Nam BH, Conboy LA, et al. Effectiveness of recruitment in clinical trials: an analysis of methods used in a trial for irritable bowel syndrome patients. Contemporary Clinical Trials 2008;29:241‐51. - PMC - PubMed
Foradori 2012 {published data only}
    1. Foradori MA, Nolan MT. Effect of a study map intended to support informed consent in transplant research. Progress in Transplantation 2012;22(1):56‐61. [DOI: 10.7182/pit2012553] - DOI - PMC - PubMed
Gallo 1995 {published data only}
    1. Gallo C, Perrone F, Placido S, Giusti C. Informed versus randomised consent to clinical trials. Lancet 1995;346:1060‐4. - PubMed
Gillan 2009 {published data only}
    1. Gillan MG, Gilbert FJ, Flight H, Cooper J, Wallis MG, James JJ, et al. Increasing participant recruitment into large‐scale screening trials: experience from the CADET II study. Journal of Medical Screening 2009;16(4):180‐5. [DOI: 10.1258/jms.2009.009023] - DOI - PubMed
Gilligan 2014 {published data only}
    1. Gilligan C, Kypri K. Recruiting by registered versus standard mail. Epidemiology 2014;25(2):317. [DOI: 10.1097/EDE.0000000000000065] - DOI - PubMed
Gillon 2009 {published data only}
    1. Gillan MG, Gilbert FJ, Flight H, Cooper J, Wallis MG, James JJ, et al. Increasing participant recruitment into large‐scale screening trials: experience from the CADET II study. Journal of Medical Screening 2009;16:180‐5. - PubMed
Ginexi 2003 {published data only}
    1. Ginexi EM, Crosse SB, Caudill BD. Alcohol abuse prevention programming for fraternity members: are we reaching the heaviest drinkers?. 11th Annual Meeting of the Society for Research Prevention. 2003.
Gitanjali 2003 {published data only}
    1. Gitanjali B, Raveendran R, Pandian DG, Sujindra S. Recruitment of subjects for clinical trials after informed consent: does gender and educational status make a difference?. Stroke 2003;34:e109‐37. - PubMed
Goldstein 2010 {published data only}
    1. Goldstein JN, Delaney KE, Pelletier AJ, Fisher J, Blanc PG, Halsey M, et al. A brief educational intervention may increase public acceptance of emergency research without consent. Journal of Emergency Medicine 2010;39(4):419‐35. [DOI: 10.1016/j.jemermed.2007.12.033] - DOI - PubMed
Gomez 1998 {published data only}
    1. Gómez Arnáu JI. Preoperative information and informed consent from surgical patients. Revista Española de Anestesiologia y Reanimacion 1998;45(9):401. - PubMed
Graham 2011 {published data only}
    1. Graham AL, Lopez‐Class M, Mueller NT, Mota G, Mandelblatt J. Efficiency and cost‐effectiveness of recruitment methods for male Latino smokers. Health Education & Behavior 2011;38(3):293‐300. [DOI: 10.1177/1090198110372879] - DOI - PMC - PubMed
Grubbs 2009 {published data only}
    1. Grubbs SS, Gonzalez M, Krasna M, Siegel R, Bryant D, Tschetter L, et al. Tracking clinical trial accrual strategies and barriers via a Web‐based screening tool. Journal of Clinical Oncology 2009;27(15 Suppl).
Halpern 2002 {published data only}
    1. Halpern S. Challenges to improving the impact of worksite cancer prevention programs: comparing reach, enrollment, and attrition using active versus passive recruitment strategies. Controlled Clinical Trials 2002;24:274‐88. - PubMed
Harris 2008 {published data only}
    1. Harris TJ, Carey IM, Victor CR, Adams R, Cook DG. Optimising recruitment into a study of physical activity in older people: a randomised controlled trial of different approaches. Age and Ageing 2008;37:659‐65. - PubMed
Harron 2012 {published data only}
    1. Harron K, Lee T, Ball T, Mok Q, Gamble C, Macrae D, et al. CATCH team. Making co‐enrolment feasible for randomised controlled trials in paediatric intensive care. PLOS ONE 2012;7(8):e41791. [DOI: 10.1371/journal.pone.0041791] - DOI - PMC - PubMed
Heiney 2010 {published data only}
    1. Heiney SP, Arp Adams S, Drake BF, Bryant LH, Bridges L, Hebert JR. Successful subject recruitment for a prostate cancer behavioral intervention trial. Clinical Trials 2010;7(4):411‐7. [DOI: 10.1177/1740774510373491] - DOI - PMC - PubMed
Henkel 2010 {published data only}
    1. Henkel V, Mergl R, Allgaier AK, Hautzinger M, Kohnen R, Coyne JC, et al. Treatment of atypical depression: post‐hoc analysis of a randomized controlled study testing the efficacy of sertraline and cognitive behavioural therapy in mildly depressed outpatients. European Psychiatry 2010;25(8):491‐8. [DOI: 10.1016/j.eurpsy.2010.01.010] - DOI - PubMed
Hillsdon 2011 {published data only}
    1. Hillsdon M. Rates of recruitment from systematic and opportunistic methods: preliminary results from the DDELPHI study. Trials 2011;12(Suppl 1):A112.
Hoffner 2011 {published data only}
    1. Hoffner B, Bauer‐Wu S, Hitchcock‐Bryan S, Powell M, Wolanski A, Joffe S. "Entering a Clinical Trial: Is it Right for You?": a randomized study of the clinical trials video and its impact on the informed consent process. Cancer 2012;118(7):1877‐83. [DOI: 10.1002/cncr.26438] - DOI - PMC - PubMed
Homish 2009 {published data only}
    1. Homish GG, Leonard KE. Testing methodologies to recruit adult drug‐using couples. Addictive Behaviors 2009;34(1):96‐9. [DOI: 10.1016/j.addbeh.2008.08.002] - DOI - PMC - PubMed
Jaffee 2009 {published data only}
    1. Jaffee WB, Bailey GL, Lohman M, Riggs P, McDonald L, Weiss RD. Methods of recruiting adolescents with psychiatric and substance use disorders for a clinical trial. American Journal of Drug and Alcohol Abuse 2009;35(5):381‐4. [DOI: 10.1080/00952990903150860] - DOI - PMC - PubMed
Jay 2007 {published data only}
    1. Jay F, Chantler T, Lees A, Pollard AJ. Children's participation in vaccine research: parents' views. Paediatric Nursing 2007;19:14‐8. - PubMed
Jenkins 2013 {published data only}
    1. Jenkins VA, Farewell D, Farewell V, Batt L, Wagstaff J, Langridge C, et al. Teams Talking Trials: results of an RCT to improve the communication of cancer teams about treatment trials. Contemporary Clinical Trials 2013;35(1):43‐51. [DOI: 10.1016/j.cct.2013.02.003] - DOI - PubMed
Ji 2008 {published data only}
    1. Ji P, DuBois DL, Flay BR, Brechling V. "Congratulations, you have been randomized into the control group!(?)": issues to consider when recruiting schools for matched‐pair randomized control trials of prevention programs. Journal of School Health 2008;78:131‐9. - PubMed
Junghans 2005 {published data only}
    1. Junghans C, Feder G, Hemingway H, Timmis A, Jones M. Recruiting patients to medical research: double blind randomised trial of "opt‐in" versus "opt‐out" strategies. BMJ 2005;331:940. - PMC - PubMed
Juraskova 2014 {published data only}
    1. Juraskova I, Butow P, Bonner C, Bell ML, Smith AB, Seccombe M, et al. Improving decision making about clinical trial participation ‐ a randomised controlled trial of a decision aid for women considering participation in the IBIS‐II breast cancer prevention trial. British Journal of Cancer 2014;111(1):1‐7. [DOI: 10.1038/bjc.2014.144] - DOI - PMC - PubMed
Karlawish 2008 {published data only}
    1. Karlawish J, Cary MS, Rubright J, Tenhave T. How redesigning AD clinical trials might increase study partners willingness to participate. Neurology 2008;71:1883‐8. - PMC - PubMed
Keedy 2009 {published data only}
    1. Keedy VL, Horn L, Hayes A, Spencer B, Garcia G, Campbell N, et al. Enrollment of lung cancer patients on clinical trials at an NCI comprehensive cancer center. Journal of Clinical Oncology 2009;27(Suppl 15):355s.
Kelechi 2010 {published data only}
    1. Kelechi T, Watts A, Wiseman J. Recruitment strategy effectiveness for a cryotherapy intervention for a venous leg ulcer prevention study. Journal of Wound, Ostomy and Continence Nursing 2010;37:39‐45. - PMC - PubMed
Kernan 2009 {published data only}
    1. Kernan WN, Viscoli CM, Demarco D, Mendes B, Shrauger K, Schindler JL, et al. Boosting enrollment in neurology trials with Local Identification and Outreach Networks (LIONs). Neurology 2009;72:1345‐51. [DOI: 10.1212/WNL.0b013e3181a0fda3] - DOI - PMC - PubMed
Kiernan 2000 {published data only}
    1. Kiernan M, Phillips K, Fair J, King AC. Using direct mail to recruit Hispanic adults into a dietary intervention: an experimental study. Annals of Behavioral Medicine 2000;22(1):89‐93. - PubMed
Kirkby 2013 {published data only}
    1. Kirkby HM, Calvert M, McManus RJ, Draper H. Informing potential participants about research: observational study with an embedded randomized controlled trial. PLOS ONE 2013;8(10):e76435. [DOI: 10.1371/journal.pone.0076435] - DOI - PMC - PubMed
Korde 2009 {published data only}
    1. Korde LA, Micheli A, Smith AW, Venzon D, Prindiville SA, Drinkard B, et al. Recruitment to a physical activity intervention study in women at increased risk of breast cancer. BMC Medical Research Methodology 2009;9:27. - PMC - PubMed
Kruse 2000 {published data only}
    1. Kruse AY, Kjaergard LL, Krogsgaard K, Gluud C, Mortensen EL, Gottschau A, et al. A randomized trial assessing the impact of written information on outpatients' knowledge about and attitude toward randomized clinical trials. The INFO trial group. Controlled Clinical Trials 2000;21:223‐40. - PubMed
Labrique 2011 {published data only}
    1. Labrique AB, Christian P, Klemm RD, Rashid M, Shamim AA, Massie Aet al. A cluster‐randomized, placebo‐controlled, maternal vitamin a or beta‐carotene supplementation trial in Bangladesh: design and methods. Trials 2011;12:102. [DOI: 10.1186/1745-6215-12-102] - DOI - PMC - PubMed
Lancet 2001 {published data only}
    1. Recruitment of women to clinical trials. Lancet 2001;358:853. - PubMed
Lang 1991 {published data only}
    1. Lang JM, Buring JE, Rosner B, Cook N, Hennekens CH. Estimating the effect of the run‐in on the power of the Physicians' Health Study. Statistics in Medicine 1991;10:1585‐93. - PubMed
Larkey 2009 {published data only}
    1. Larkey LK, Gonzalez JA, Mar LE, Glantz N. Latina recruitment for cancer prevention education via Community Based Participatory Research strategies. Contemporary Clinical Trials 2009;30:47‐54. - PubMed
Leader 1978 {published data only}
    1. Leader MA, Neuwirth E. Clinical research and the noninstitutional elderly: a model for subject recruitment. Journal of the American Geriatrics Society 1978;26:27‐31. - PubMed
Lee 2011 {published data only}
    1. Lee JY, Foster HE Jr, McVary KT, Meleth S, Stavris K, Downey J, Kusek JW. Recruitment of participants to a clinical trial of botanical therapy for benign prostatic hyperplasia. Journal of Alternative and Complementary Medicine (New York) 2011;17(5):469‐72. [DOI: 10.1089/acm.2010.0300] - DOI - PMC - PubMed
Lichter 1991 {published data only}
    1. Lichter PR. Patient recruitment for clinical trials. Ophthalmology 1991;98:1489‐90. - PubMed
Lloyd‐Williams 2002 {published data only}
    1. Lloyd‐Williams F, Beaton S, Mair FS, Shiels C, Goldstein P, Hanratty B, et al. Recruiting heart failure patients to clinical trials: the experience of a randomised controlled trial in primary care. Society for Social Medicine 46th Annual Scientific Meeting. 2002.
Macias 2005 {published data only}
    1. Macias C, Barreira P, Hargreaves W, Bickman L, Fisher W, Aronson E. Impact of referral source and study applicants' preference for randomly assigned service on research enrollment, service engagement, and evaluative outcomes. American Journal of Psychiatry 2005;162:781‐7. - PMC - PubMed
Marco 2008 {published data only}
    1. Marco CA. Impact of detailed informed consent on research subjects' participation: a prospective, randomized trial. Journal of Emergency Medicine 2008;34:269‐75. - PubMed
Masood 2006 {published data only}
    1. Masood J, Hafeez A, Wiseman O, Hill JT. Informed consent: are we deluding ourselves? A randomized controlled study. BJU International 2006;99:4‐5. - PubMed
May 2007 {published data only}
    1. May DE, Hallin MJ, Kratochvil CJ, Puumala SE, Smith LS, Reinecke MA, et al. Factors associated with recruitment and screening in the Treatment for Adolescents With Depression Study (TADS). Journal of the American Academy of Child and Adolescent Psychiatry 2007;46:801‐10. - PubMed
McGuire 2011 {published data only}
    1. McGuire AL, Oliver JM, Slashinski MJ, Graves JL, Wang T, Kelly PA, et al. To share or not to share: a randomized trial of consent for data sharing in genome research. Genetics in Medicine 2011;13(11):948‐55. [DOI: 10.1097/GIM.0b013e3182227589] - DOI - PMC - PubMed
Menoyo 2006 {published data only}
    1. Menoyo E, Perez M, 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.
Monane 1991 {published data only}
    1. Monane M, et al. The randomized controlled trial in the long‐term care setting ‐ recruitment and enrollment. Journal of the American Geriatrics Society 1991;39:A51.
Murphy 2011 {published data only}
    1. Murphy M, Merenstein D. Grassroots campaign trail methods to recruit for clinical trials: recruitment lessons learned from trail to trial. Clinical Medicine Insights: Pediatrics 2011;5:1‐7. [DOI: 10.4137/CMPed.S6488] - DOI - PMC - PubMed
O'Lonergan 2011 {published data only}
    1. O'Lonergan TA, Forster‐Harwood JE. Novel approach to parental permission and child assent for research: improving comprehension. Pediatrics 2011;127(5):917‐24. [DOI: 10.1542/peds.2010-3283] - DOI - PMC - PubMed
Olver 2009 {published data only}
    1. Olver IN, Whitford HS, Denson LA, Peterson MJ, Olver SI. Improving informed consent to chemotherapy: a randomized controlled trial of written information versus an interactive multimedia CD‐ROM. Patient Education and Counseling 2009;74:197‐204. - PubMed
Paskett 2002 {published data only}
    1. Paskett ED, Cooper MR, Stark N, Ricketts TC, Tropman S, Hatzell T, et al. Clinical trial enrollment of rural patients with cancer. Cancer Practice 2002;10:28‐35. - PubMed
Perri 2006 {published data only}
    1. Perri R, Wollin S, Drolet N, Mai S, Awad M, Feine J. Monitoring recruitment success and cost in a randomized clinical trial. European Journal of Prosthodontics & Restorative Dentistry 2006;14:126‐30. - PubMed
Porucznik 2010 {published data only}
    1. Porucznik CA, Schliep KC, Stanford JB. Participant recruitment in a virtually interconnected world: comparative effectiveness and considerations of bias. American Journal of Epidemiology 2010;171(Suppl):s147.
Quinaux 2003 {published data only}
    1. Quinaux E, Liénard JL, Slimani Z, Jouhaud A, Piedbois P, Buyse M. Impact of monitoring visits on patient recruitment and data quality: case study of a phase IV trial in oncology. Controlled Clinical Trials 2003;24:99S.
Rogers 1998 {published data only}
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References to studies awaiting assessment

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