Why is it important for participants to be unaware of what the research study is about before participating in the study?

1. McDonald AM, Knight RC, Campbell MK, Entwistle VA, Grant AM, Cook JA, et al. What influences recruitment to randomised controlled trials? A review of trials funded by two UK funding agencies. Trials. 2006;7(1):9.

   PubMed  PubMed Central  Google Scholar 

2. Briel M, Olu KK, von Elm E, Kasenda B, Alturki R, Agarwal A, et al. A systematic review of discontinued trials suggested that most reasons for recruitment failure were preventable. J Clin Epidemiol. 2016;1(80):8–15.

   Google Scholar 

3. Walters SJ, Bonacho dos Anjos Henriques-Cadby I, Bortolami O, Flight L, Hind D, Jacques RM, et al. Recruitment and retention of participants in randomised controlled trials: a review of trials funded and published by the United Kingdom Health Technology Assessment Programme. BMJ Open. 2017;7(3):e015276.

   PubMed  PubMed Central  Google Scholar 

4. Treweek S, Lockhart P, Pitkethly M, Cook JA, Kjeldstrom M, Johansen M, et al. Methods to improve recruitment to randomised controlled trials: Cochrane systematic review and meta-analysis. BMJ Open. 2013;3(2):e002360.

   PubMed  PubMed Central  Google Scholar 

5. Treweek S, Mitchell E, Pitkethly M, Cook J, Kjeldstrøm M, Taskila T, Johansen M, Sullivan F, Wilson S, Jackson C, Jones R. Strategies to improve recruitment to randomised controlled trials. Cochrane Database Syst Rev. 2010;(1):MR000013. https://doi.org/10.1002/14651858.MR000013.pub4.

6. Healy P, Galvin S, Williamson PR, Treweek S, Whiting C, Maeso B, et al. Identifying trial recruitment uncertainties using a James Lind Alliance Priority Setting Partnership–the PRioRiTy (Prioritising Recruitment in Randomised Trials) study. Trials. 2018;19(1):147.

   PubMed  PubMed Central  Google Scholar 

7. Mapstone J, Elbourne D, Roberts I. Strategies to improve recruitment to research studies. Cochrane Database Syst Rev. 2007;2:Mr000013.

   Google Scholar 

8. Treweek S, Pitkethly M, Cook J, Fraser C, Mitchell E, Sullivan F, et al. Strategies to improve recruitment to randomised trials. Cochrane Database Syst Rev. 2018;2:Mr000013.

   PubMed  Google Scholar 

9. Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the PRISMA statement. BMJ. 2009;151(4):264–9.

   Google Scholar 

10. Fayter D, McDaid C, Eastwood A. A systematic review highlights threats to validity in studies of barriers to cancer trial participation. J Clin Epidemiol. 2007;60(10):990.e1–e33.

    Google Scholar 

11. Centre for Reviews and Dissemination. Search strategies for DARE. 2015. http://www.crd.york.ac.uk/crdweb/searchstrategies.asp. Accessed 01 June 2016.

12. Shea BJ, Grimshaw JM, Wells GA, Boers M, Andersson N, Hamel C, et al. Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews. BMC Med Res Methodol. 2007;7(1):10.

    PubMed  PubMed Central  Google Scholar 

13. Marchi J, Berg M, Dencker A, Olander EK, Begley C. Risks associated with obesity in pregnancy, for the mother and baby: a systematic review of reviews. Obes Rev. 2015;16(8):621–38.

    CAS  PubMed  Google Scholar 

14. Cane J, O’Connor D, Michie S. Validation of the theoretical domains framework for use in behaviour change and implementation research. Implement Sci. 2012;7(1):37.

    PubMed  PubMed Central  Google Scholar 

15. Atkins L, Francis J, Islam R, O'Connor D, Patey A, Ivers N, et al. A guide to using the Theoretical Domains Framework of behaviour change to investigate implementation problems. Implement Sci. 2017;12(1):77.

    PubMed  PubMed Central  Google Scholar 

16. Carey RN, Connell LE, Johnston M, Rothman AJ, de Bruin M, Kelly MP, et al. Behavior change techniques and their mechanisms of action: a synthesis of links described in published intervention literature. Ann Behav Med. 2019;53(8):693–707.

    PubMed  Google Scholar 

17. Michie S, van Stralen MM, West R. The behaviour change wheel: a new method for characterising and designing behaviour change interventions. ImplementSci. 2011;6(1):42.

    Google Scholar 

18. Crane S, Broome ME. Understanding ethical issues of research participation from the perspective of participating children and adolescents: a systematic review. Worldviews Evid-Based Nurs. 2017;14(3):200–9.

    PubMed  PubMed Central  Google Scholar 

19. Dhalla S, Poole G. Barriers to participation in actual HIV vaccine trials. Curr HIV Res. 2013;11(3):238–45.

    CAS  PubMed  Google Scholar 

20. Dhalla S, Poole G. Motivators to participation in actual HIV vaccine trials. AIDS Behav. 2014;18(2):263–77.

    PubMed  Google Scholar 

21. Fisher HR, McKevitt C, Boaz A. Why do parents enroll their children in research: a narrative synthesis. J Med Ethics. 2011;37(9):544–51.

    PubMed  Google Scholar 

22. Forcina V, Vakeesan B, Paulo C, Mitchell L, Bell JA, Tam S, et al. Perceptions and attitudes toward clinical trials in adolescent and young adults with cancer: a systematic review. Adolesc Health Med Ther. 2018;9:87–94.

    PubMed  PubMed Central  Google Scholar 

23. Gad KT, Lassen U, Mau-Soerensen M, Hoybye MT, Johansen C. Patient information in phase 1 trials: a systematic review. Psychooncology. 2018;27(3):768–80.

    PubMed  Google Scholar 

24. Glover M, Kira A, Johnston V, Walker N, Thomas D, Chang AB, et al. A systematic review of barriers and facilitators to participation in randomized controlled trials by Indigenous people from New Zealand, Australia, Canada and the United States. Glob Health Promot. 2015;22(1):21–31.

    PubMed  Google Scholar 

25. Grand MM, O'Brien PC. Obstacles to participation in randomised cancer clinical trials: a systematic review of the literature. J Med Imaging Radiat Oncol. 2012;56(1):31–9.

    PubMed  Google Scholar 

26. Gregersen TA, Steffensen KD, Birkelund R, Wolderslund M, Ammentorp J, Netsey-Afedo ML. What matters in clinical trial decision-making: a systematic review of interviews exploring cancer patients’ experiences. Scand J Caring Sci. 2019;33(2):266–78.

    PubMed  Google Scholar 

27. Hughes-Morley A, Young B, Waheed W, Small N, Bower P. Factors affecting recruitment into depression trials: systematic review, meta-synthesis and conceptual framework. J Affect Disord. 2015;172:274–90.

    PubMed  Google Scholar 

28. Liljas AEM, Walters K, Jovicic A, Iliffe S, Manthorpe J, Goodman C, et al. Strategies to improve engagement of ‘hard to reach’ older people in research on health promotion: a systematic review. BMC Public Health. 2017;17(1):349.

    PubMed  PubMed Central  Google Scholar 

29. Limkakeng A, Phadtare A, Shah J, Vaghasia M, Wei DY, Shah A, et al. Willingness to participate in clinical trials among patients of Chinese heritage: a meta-synthesis. PLOS One. 2013a;8(1):e51328.

    CAS  PubMed  PubMed Central  Google Scholar 

30. Limkakeng AT, de Oliveira LLH, Moreira T, Phadtare A, Rodrigues CG, Hocker MB, et al. Systematic review and metasummary of attitudes toward research in emergency medical conditions. J Med Ethics. 2013b;40(6):401–8.

    PubMed  Google Scholar 

31. Martinsen EMH, Leiten EO, Bakke PS, Eagan TML, Grønseth R. Participation in research bronchoscopy: a literature review. Eur Clin Respir J. 2016;3(1):29511.

    PubMed  Google Scholar 

32. McCann S. Patients’ perspectives on participation in randomised controlled trials. Aberdeen: University of Aberdeen; 2007.

    Google Scholar 

33. McCann S, Campbell M, Entwistle V. Recruitment to clinical trials: a meta-ethnographic synthesis of studies of reasons for participation. J Health Serv Res Policy. 2013;18(4):233–41.

    PubMed  Google Scholar 

34. Nalubega S, Evans C. Participant views and experiences of participating in HIV research in sub-Saharan Africa: a qualitative systematic review. JBI Database System Rev Implement Rep. 2015;13(5):330–420.

    PubMed  Google Scholar 

35. Nielsen ZE, Berthelsen CB. Cancer patients’ perceptions of factors influencing their decisions on participation in clinical drug trials: a qualitative meta-synthesis. J Clin Nurs. 2019;28(13–14):2443–61.

    PubMed  Google Scholar 

36. Nievaard M, De Vos R, de Haes J, Levi M. Reasons why patients do or do not participate in clinical trials; a systemic review of the literature. Ned Tijdschr Geneeskd. 2004;148(4):186–90.

    CAS  PubMed  Google Scholar 

37. Nobile H, Vermeulen E, Thys K, Bergmann MM, Borry P. Why do participants enroll in population biobank studies? A systematic literature review. Expert Rev Mol Diagn. 2013;13(1):35–47.

    CAS  PubMed  Google Scholar 

38. Prescott RJ, Counsell CE, Gillespie WJ, Grant AM, Russell IT, Kiauka S, et al. Factors that limit the quality, number and progress of randomised controlled trials. Health Technol Assess. 1999;3(20):1–143.

    CAS  PubMed  Google Scholar 

39. Quay TA, Frimer L, Janssen PA, Lamers Y. Barriers and facilitators to recruitment of South Asians to health research: a scoping review. BMJ Open. 2017;7(5):e014889.

    PubMed  PubMed Central  Google Scholar 

40. Tromp K, Zwaan CM, van de Vathorst S. Motivations of children and their parents to participate in drug research: a systematic review. Eur J Pediatr. 2016;175(5):599–612.

    PubMed  PubMed Central  Google Scholar 

41. van der Zande ISE, van der Graaf R, Hooft L, van Delden JJM. Facilitators and barriers to pregnant women’s participation in research: a systematic review. Women Birth. 2018;31(5):350–61.

    PubMed  Google Scholar 

42. Woodall A, Morgan C, Sloan C, Howard L. Barriers to participation in mental health research: are there specific gender, ethnicity and age related barriers? BMC Psychiatry. 2010;10(1):103.

    PubMed  PubMed Central  Google Scholar 

43. Pieper D, Antoine S-L, Mathes T, Neugebauer EA, Eikermann M. Systematic review finds overlapping reviews were not mentioned in every other overview. J Clin Epidemiol. 2014;67(4):368–75.

    PubMed  Google Scholar 

44. Hunt H, Pollock A, Campbell P, Estcourt L, Brunton G. An introduction to overviews of reviews: planning a relevant research question and objective for an overview. Syst Rev. 2018;7(1):39.

    PubMed  PubMed Central  Google Scholar 

45. McKenzie JE, Brennan SE. Overviews of systematic reviews: great promise, greater challenge. Syst Rev. 2017;6(1):185.

    PubMed  PubMed Central  Google Scholar 

46. Pollock A, Campbell P, Brunton G, Hunt H, Estcourt L. Selecting and implementing overview methods: implications from five exemplar overviews. Syst Rev. 2017;6(1):145.

    PubMed  PubMed Central  Google Scholar 

47. Ballard M, Montgomery P. Risk of bias in overviews of reviews: a scoping review of methodological guidance and four-item checklist. Res Synth Methods. 2017;8(1):92–108.

    PubMed  Google Scholar 

48. Health Research Authority. Informing participants and seeking consent. 2019. https://www.hra.nhs.uk/planning-and-improving-research/best-practice/informing-participants-and-seeking-consent/. Accessed 01 April 2019.

49. Woolfall K, Shilling V, Hickey H, Smyth RL, Sowden E, Williamson PR, et al. Parents’ agendas in paediatric clinical trial recruitment are different from researchers’ and often remain unvoiced: a qualitative study. PLOS One. 2013;8(7):e67352.

    CAS  PubMed  PubMed Central  Google Scholar 

50. Martin-Kerry JM, Knapp P, Atkin K, Bower P, Watt I, Stones C, et al. Supporting children and young people when making decisions about joining clinical trials: qualitative study to inform multimedia website development. BMJ Open. 2019;9:1.

    Google Scholar 

51. Sheridan R, Martin-Kerry J, Watt I, Higgins S, Stones S, Horton Taylor D, et al. User testing digital, multimedia information to inform children, adolescents and their parents about healthcare trials. J Child Health Care. 2018;23(3):468–82.

    PubMed  Google Scholar 

52. Bower P, King M, Nazareth I, Lampe F, Sibbald B. Patient preferences in randomised controlled trials: conceptual framework and implications for research. Soc Sci Med. 2005;61(3):685–95.

    PubMed  Google Scholar 

Page 2

Methods: questionnaires, interviews, surveys, review of patient/trial records, focus groups