Recruitment of Study Participants

  • Lawrence M. Friedman
  • Curt D. Furberg
  • David L. DeMets


Often the most difficult task in a clinical trial involves obtaining sufficient study participants within a reasonable time. Time is a critical factor for both scientific and logistical reasons. From a scientific viewpoint, there is an optimal window of time within which a clinical trial can and should be completed. Changes in medical practice, including introduction of new treatment options, may make the trial outdated before it is completed. Other investigators may answer the questions sooner. In terms of logistics, the longer recruitment extends beyond the initially allotted recruitment periods, the greater the pressure becomes to meet the goal. Lagging recruitment will also reduce the statistical power of the trial. Costs increase, frustration, and discouragement often follow. The primary reasons for recruitment failure include overoptimistic expectations, failure to start on time, inadequate planning, and insufficient effort.


Potential Participant Recruitment Effort Physician Referral Recruitment Approach Recruitment Goal 


  1. 1.
    ECRI Health Technology Assessment Information Service. Patients’ reasons for participation in clinical trials and effect of trial participation on patient outcomes. ECRI Evidence Report. April 2002, Issue 74.Google Scholar
  2. 2.
    Wright JR, Crooks D, Ellis PM, et al. Factors that influence the recruitment of patients to phase III studies in oncology. The perspective of the clinical research assistant. Cancer 2002;95:1584–1591.CrossRefGoogle Scholar
  3. 3.
    Cox K, McGarry J. Why patients don’t take part in cancer clinical trials: an overview of the literature. Eur J Cancer Care 2003;12:114–122.CrossRefGoogle Scholar
  4. 4.
    Sharp L, Cotton SC, Alexander L, et al. on behalf of the TOMBOLA group. Reasons for participation and non-participation in a randomized controlled trial: postal questionnaire surveys of women eligible for TOMBOLA (Trial of Management of Borderline and Other Low-grade Abnormal smears). Clin Trials 2006;3:431–442.Google Scholar
  5. 5.
    Barnes K. Patients provide insight into trial participation., July 4, 2007.
  6. 6.
    Mills EJ, Seely D, Rachlis B, et al. Barriers to participation in clinical trials of cancer: a meta-analysis and systematic review of patient-reported factors. Lancet Oncol 2006;7:141–148.CrossRefGoogle Scholar
  7. 7.
    Lovato LC, Hill K, Hertert S, et al. Recruitment for controlled clinical trials: literature summary and annotated bibliography. Control Clin Trials 1997;18:328–357.CrossRefGoogle Scholar
  8. 8.
    McDonald AM, Knight RC, Campbell MK, et al. What influences recruitment to randomised controlled trials? A review of trials funded by two UK funding agencies. Trials 2006;7:9.CrossRefGoogle Scholar
  9. 9.
    Watson JM, Torgerson DJ. Increasing recruitment to randomised trials: a review of randomised controlled trials. BMC Med Res Methodol doi:10.1186/1471-2288-6-34 (published 19 July 2006).Google Scholar
  10. 10.
    Kääriäinen I, Sipponen P, Siurala M. What fraction of hospital ulcer patients is eligible for prospective drug trials? Scand J Gastroenterol 1991;186:73–76.CrossRefGoogle Scholar
  11. 11.
    Sheldon T. Dutch neurologist found guilty of fraud after falsifying 438 case records. Br Med J 2002;325:734.CrossRefGoogle Scholar
  12. 12.
    Ross DB. The FDA and the case of Ketek. N Engl J Med 2007;356:1601–1604.CrossRefGoogle Scholar
  13. 13.
    POISE Study Group. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial): a randomised controlled trial. Lancet 2008;371:1839–1847 (Web attachment 1).CrossRefGoogle Scholar
  14. 14.
    Hunninghake DB. Summary conclusions. Control Clin Trials 1987;8:1S–5S.CrossRefGoogle Scholar
  15. 15.
    Kingry C, Bastien A, Booth G, et al. for the ACCORD Study Group. Recruitment strategies in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) Trial. Am J Cardiol 2007;99(Suppl):68i–79i.Google Scholar
  16. 16.
    Hulley SB, Furberg CD, Gurland B, et al. Systolic Hypertension in the Elderly Program (SHEP): antihypertensive efficacy of chlorthalidone. Am J Cardiol 1985;56:913–920.CrossRefGoogle Scholar
  17. 17.
    Cosgrove N, Borhani NO, Bailey G, et al. Mass mailing and staff experience in a total recruitment program for a clinical trial: the SHEP experience. Control Clin Trials 1999;19:133–148.CrossRefGoogle Scholar
  18. 18.
    Bryant J, Powell J. Payment to healthcare professionals for patient recruitment to trials: a systematic review. Br Med J 2005;331:1377–1378.CrossRefGoogle Scholar
  19. 19.
    Freedman LS, Simon R, Foulkes MA, et al. Inclusion of women and minorities in clinical trials and the NIH Revitalization Act of 1993 – the perspective of NIH clinical trialists. Control Clin Trials 1995;16:277–285.CrossRefGoogle Scholar
  20. 20.
    Cook ED, Moody-Thomas S, Anderson KB, et al. Minority recruitment to the Selenium and Vitamin E Cancer Prevention Trial (SELECT). Clin Trials 2005;2:436–442.CrossRefGoogle Scholar
  21. 21.
    Shibata M, Flather M, de Arenaza DP, et al. Potential impact of socioeconomic differences on clinical outcomes in international clinical trials. Am Heart J 2001;1411:1019–1024.CrossRefGoogle Scholar
  22. 22.
    Orlandini A, Diaz R, Wojdyla D, et al. Outcomes of patients in clinical trials with ST-segment elevation myocardial infarction among countries with different gross national incomes. Eur Heart J 2006;27:527–533.CrossRefGoogle Scholar
  23. 23.
    O’Shea JC, Califf RM. International differences in cardiovascular clinical trials. Am Heart J 2001;141:866–874.CrossRefGoogle Scholar
  24. 24.
    Vickers A, Goyal N, Harland R, Rees R. Do certain countries produce only positive results? A systematic review of controlled trials. Control Clin Trials 1998;19:159–166.CrossRefGoogle Scholar
  25. 25.
    Durkin DA, Kjelsberg MO, Buist AS, et al. Recruitment of participants in the Lung Health Study, I: description of methods. Control Clin Trials 1993;14:20S–37S.CrossRefGoogle Scholar
  26. 26.
    Daly M, Seay J, Balshem A, et al. Feasibility of a telephone survey to recruit health maintenance organization members into a tamoxifen chemoprevention trial. Cancer Epidemiol Biomarkers Prev 1992;1:413–416.Google Scholar
  27. 27.
    Fields WS, Lemak NA, Frankowski RF, et al. Controlled trial of aspirin in cerebral ischemia. Stroke 1977;8:301–314.CrossRefGoogle Scholar
  28. 28.
    The Coronary Drug Project Research Group. The Coronary Drug Project: design, methods, and baseline results. Circulation 1973;47:I-1–I-50.CrossRefGoogle Scholar
  29. 29.
    The Coronary Drug Project Research Group. Clofibrate and niacin in coronary heart disease. JAMA 1975;231:360–381.CrossRefGoogle Scholar
  30. 30.
    Sackett DL. A compliance practicum for the busy practitioner. In Haynes RB, Taylor DW, Sackett DL (eds.). Compliance in Health Care. Baltimore: Johns Hopkins University Press, 1979.Google Scholar
  31. 31.
    Julian D. The data monitoring experience in the Carvedilol Post-Infarct Survival Control in Left Ventricular Dysfunction Study: hazards of changing primary outcomes. In DeMets DL, Furberg CD, Friedman LM (eds.). Data Monitoring in Clinical Trials. New York: Springer, 2006, pp. 337–345.CrossRefGoogle Scholar

Copyright information

© Springer New York 2010

Authors and Affiliations

  • Lawrence M. Friedman
    • 1
  • Curt D. Furberg
    • 2
  • David L. DeMets
    • 3
  1. 1.BethesdaUSA
  2. 2.School of MedicineWake Forest UniversityWinston-SalemUSA
  3. 3.Department of Biostatistics & Medical InformaticsUniversity of WisconsinMadisonUSA

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