Table 5 Summary of the results from ‘ recruitment ’ studies included in the review (n = 58 studies)

Lack of trust in research/research team or uncertainty regarding how survey results will be used

• Community-driven research [44, 56, 70, 71, 75, 114] and community partnerships [18, 28, 75, 77, 78, 80, 93, 94],[100, 101, 113, 115].

Fear of authority

• Peer or known recruiters [21, 28, 40, 74, 82, 96, 113, 115],[105, 121, 123, 124].

Perceived harms of research

• Sensitive wording: “study”, “conversation” and “dialogue” instead of “investigation”, “research” and “interview” [26, 47, 60, 92].

Mistreatment and exploitation

• Use of ‘hand-written’ envelopes (vs. printed) [106]*

No benefits for participation (i.e., ‘fly in, fly out’ research)

• Enlisting community leaders (60, 113,114,115,127].

• Commitment to “give back” to the community through sustainable interventions [31, 94, 114, 115] or reciprocal benefits [64, 74, 101] or if not resourced to provide intervention, provide links to services [118] or minimal intervention controls [44].

• Shared data ownership and publication [114, 118]

• Gifts with project logo [18, 30, 92–94, 118, 127] and incentives [42, 47, 119, 123].

• Thank you and award ceremonies and project feedback [114, 118].

• Emphasising potential benefits [74].

• Improved communication and culturally relevant education materials [32].

Lack of education/awareness re research or health promotion/low health literacy, difficulties understanding consent and what the study is about

• Utilising appropriate media (print vs. TV vs. online) [18, 25, 41, 56, 65, 85, 87, 119]; mass media [61, 62, 72, 81] or social marketing strategies [37, 47, 72, 83].

• Provision of participant feedback regarding the research outcomes [30, 115].

• Public information sessions [47, 116].

• Simplified consent forms – large font, plain language, shorter sentences, in respondents language, ensure translation makes sense, wide margins, shorter paragraphs [45, 86, 114].

• Bilingual recruiters and materials [18, 56, 85, 92, 104, 112]

Cultural beliefs, gender roles/age related issues

• Cultural competence skills of research team/well trained research staff [16, 22, 30, 56, 63, 101, 104, 118]

• Culturally targeted media [41, 72, 113, 115]

• Mindful different cultures require different strategies [16, 43, 63, 67, 93, 94, 103, 118],[125].

• Recruitment strategies adapted to local conditions for a community-specific approach [16, 63, 85, 86, 93, 113, 125].

Gatekeepers (therefore patients/community are not aware of research): doctors or nurses who do not approach minority participants, high turnover of staff limits relationships

• Work with gatekeepers [14, 15, 100, 103, 123], employ locals as staff [22, 55, 93, 113, 118].

Doctor poor communication methods

• Ensure appropriate authorities are consulted [113, 114].

Rigid exclusive eligibility criteria

• Patient education materials [32].

• Financial incentives for recruitment partners to employ support staff to recruit [32, 44, 143, 125].

• Flexible eligibility criteria [35, 50].

Stigma/fear of exposure

• Online focus group and interview research [51, 52] or video recruitment [46].

• Community advisory group [28, 47, 100, 113, 118].

Low response rates in general

• Multiple (>6) contact attempts [40, 66, 81, 99].

• Toll-free number [61, 70] or follow-up a mail survey with a telephone survey of non-responders [106].

• Through doctors/health services [85, 93, 103, 123].

• Outreach/home visits [21, 25, 99].

• Text messaging [65].

• Incentives [18, 30, 40, 42]*,[43]*,[70, 81, 92–94, 123, 127].

• Recruitment letters: An advance letter (prior to a mailed survey) [36]* or culturally framed letter [43]*.

• Two stage recruitment 1) to a low commitment survey then 2) to the trial [83].

• Assistance with transport or child care [30, 73].

• Shorter surveys [106].

• Develop a registry with interested people [25].