Online Resource for Recruitment Research in Clinical Trials


Successfully recruiting the pre-specified number of patients to time and target is a commonly encountered challenge that negatively impacts all stakeholders. Consequently there is a drive in research aimed at addressing trial recruitment. However, the volume of research in this area needs to be managed in an efficient way that enables trialists to access and use relevant research as well as allowing trials methodologists to identify any gaps in the research.

ORRCA aims to collate relevant methodological research on recruitment in a searchable database.


Search strategy and review process

A search of the Cochrane Library, MEDLINE (Ovid), SCOPUS, ERIC and SCI-EXPANDED and SSCI (via ISI Web of Science) was conducted in 2015 to identify relevant studies which may inform recruitment research and strategies. To date over 40,000 articles have been screened by title and abstract which has identified over 4000 articles for full text review.

A team of reviewers from the MRC HTMR recruitment working group and the HRB Trial Methodology Research network in Ireland are currently reviewing full text articles for eligibility and categorising articles according to recruitment research domains:

Articles have also been categorised according to the following types of evidence:

Evaluation – The formal assessment of the effectiveness of a recruitment strategy through a nested randomised control trial, a case control or a systematic review.

Application - Information on the use of a recruitment strategy without formal evaluation. This includes informal evaluations such as level of recruitment before and after a strategy is applied and hypothetical models of strategies.  

Observation - Concepts, observations or information that may be used to develop recruitment strategies. This includes lessons learnt from trials and reasons for participation/ non participation.

Additional information has been extracted from articles to allow users to search for articles based on the methods, outcomes and approach of the recruitment research, as well as the recruitment context (recruitment setting, gender, age, intervention type etc.)

Further information on the review process and how to use the site can be accessed via the HTMR webinar conducted in December 2016.


ORRCA Reviewers

We are incredibly grateful to the following team of reviewers who have helped make this project possible.

Abstract Screening: A. Kearney1, Dr N Harman1, Dr A Jones1, B Conroy1, N Bacon1, A Rosala- Hallas1,  M, Blundell1, E. Gkioni1, Dr. F. Sherratt1 and Dr J Wade4 

Full text review and categorisation of articles: Dr N Harman1, Prof. C Gamble1, A Kearney1, Dr K Woolfall1, E. Gkioni1, H. Gardner2, A El Feky2, Dr K Gillies2, Dr L Maguire3, Dr L Rooshenas4, Dr N Mills4 , C Rowlands4, S Paramasivan4, J Dooley4, J Wade4, D Elliot4, S Husbands4, W. Cragg5, L Biesty6, Dr S Duane6, P Healy6, A Vellinga6 and C Beecher6, Karen Bracken7.

1North West Hub  Hub for Trials Methodology Research/ University of Liverpool, 2University of Aberdeen, 3Queen's University, Belfast, 4University of Bristol, 5MRC CTU, 6HRB-Trials Methodology Research Network 7 University of Sydney

If you have methodological research experience and would like to join the team please contact us at 


ORRCA Progress

The original review has been completed and an update for 2015-2016 publications is underway. 9,000 articles are currently being screened. Relevant articles will continue to be added to the database throughout the update.


ORRCA Newsletter

Previous Editions

July 2017.

October 2016.


MRC Network of Hubs for Trials Methodology Research

This work is supported by the Medical Research Council (MRC) Network of Hubs for Trials Methodology Research (MR/L004933/1– B2).