Strategies designed to help healthcare professionals to recruit participants to research studies


Most trials fail to recruit the number of participants they need within the time they had planned to conduct the study. Recruiting potential participants to research studies involves three stages: identifying, approaching and obtaining the consent of potential participants to join a study. Researchers often rely on healthcare staff, such as doctors and nurses, to identify and approach potential participants. This review examines what strategies could be used by researchers to improve recruitment to studies.


We found 11 studies that assessed recruitment strategies used with healthcare staff in search of the literature in January 2015. Five included the total number of participants (7372). There were three main strategies:

1. Using an alert system, either a computer system or member of staff to check patient records, to alert staff recruiting participants that someone might be suitable for the study (five studies).

2. Giving additional information about the study to the staff at hospitals or clinics who are recruiting people through visits from the researchers, educational seminars or leaflets (four studies).

3. Using a designated member of staff whose primary role was to recruit participants (two studies).

All the studies identified were of quite low quality, so it is difficult to draw firm conclusions from them. Five studies examined the alert system to identify participants who might be suitable for a study. Alert systems showed some promising results but were not unanimous in their findings. The four studies that evaluated the provision of additional information, visits or education to the sites recruiting participants found that none of the tested strategies led to improved recruitment. The most promising strategy appears to be the employment of someone such as a clinical trials officer or research nurse with the specific task of recruiting participants to research studies. The two studies using this strategy showed improvement in recruitment rates but both were at high risk of bias.


More research is still needed to evaluate the role of a designated person to recruit to research studies.

Authors' conclusions: 

There is no strong evidence for any single strategy to help healthcare professionals to recruit participants in research studies. Additional visits or information did not appear to increase recruitment by healthcare professionals. The most promising strategies appear to be those with a dedicated resource (e.g. a clinical recruiter or automated alert system) for identifying suitable participants that reduced the demand on healthcare professionals, but these were assessed in studies at high risk of bias.

Read the full abstract...

Identifying and approaching eligible participants for recruitment to research studies usually relies on healthcare professionals. This process is sometimes hampered by deliberate or inadvertent gatekeeping that can introduce bias into patient selection.


Our primary objective was to identify and assess the effect of strategies designed to help healthcare professionals to recruit participants to research studies.

Search strategy: 

We performed searches on 5 January 2015 in the following electronic databases: Cochrane Methodology Register, CENTRAL, MEDLINE, EMBASE, CINAHL, British Nursing Index, PsycINFO, ASSIA and Web of Science (SSCI, SCI-EXPANDED) from 1985 onwards. We checked the reference lists of all included studies and relevant review articles and did citation tracking through Web of Science for all included studies.

Selection criteria: 

We selected all studies that evaluated a strategy to identify and recruit participants for research via healthcare professionals and provided pre-post comparison data on recruitment rates.

Data collection and analysis: 

Two review authors independently screened search results for potential eligibility, read full papers, applied the selection criteria and extracted data. We calculated risk ratios for each study to indicate the effect of each strategy.

Main results: 

Eleven studies met our eligibility criteria and all were at medium or high risk of bias. Only five studies gave the total number of participants (totalling 7372 participants). Three studies used a randomised design, with the others using pre-post comparisons. Several different strategies were investigated. Four studies examined the impact of additional visits or information for the study site, with no increases in recruitment demonstrated. Increased recruitment rates were reported in two studies that used a dedicated clinical recruiter, and five studies that introduced an automated alert system for identifying eligible participants. The studies were embedded into trials evaluating care in oncology mainly but also in emergency departments, diabetes and lower back pain.

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