Open Access Research article

Recruiting older people to a randomised controlled dietary intervention trial - how hard can it be?

Sarah E Forster1*, Laura Jones1, John M Saxton2, Daniel J Flower1, Gemma Foulds1, Hilary J Powers1, Stuart G Parker3, A Graham Pockley1 and Elizabeth A Williams1

Author Affiliations

1 Department of oncology, Faculty of Medicine and Dentistry and Health, The University of Sheffield, Royal Hallamshire Hospital, Glossop Rd, Sheffield, S10 2JF, UK

2 Centre for Sport and Exercise Science, Sheffield Hallam University, Collegiate Crescent Campus, Sheffield, S10 2BP, UK

3 Sheffield Institute for Studies on Ageing, School Faculty of Medicine, 2nd Floor, Samuel Fox House, Northern General Hospital, Herries Road, Sheffield, S5 7AU, UK

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BMC Medical Research Methodology 2010, 10:17  doi:10.1186/1471-2288-10-17

Published: 22 February 2010



The success of a human intervention trial depends upon the ability to recruit eligible volunteers. Many trials fail because of unrealistic recruitment targets and flawed recruitment strategies. In order to predict recruitment rates accurately, researchers need information on the relative success of various recruitment strategies. Few published trials include such information and the number of participants screened or approached is not always cited.


This paper will describe in detail the recruitment strategies employed to identify older adults for recruitment to a 6-month randomised controlled dietary intervention trial which aimed to explore the relationship between diet and immune function (The FIT study). The number of people approached and recruited, and the reasons for exclusion, will be discussed.


Two hundred and seventeen participants were recruited to the trial. A total of 7,482 letters were sent to potential recruits using names and addresses that had been supplied by local Family (General) Practices. Eight hundred and forty three potential recruits replied to all methods of recruitment (528 from GP letters and 315 from other methods). The eligibility of those who replied was determined using a screening telephone interview, 217 of whom were found to be suitable and agreed to take part in the study.


The study demonstrates the application of multiple recruitment methods to successfully recruit older people to a randomised controlled trial. The most successful recruitment method was by contacting potential recruits by letter on NHS headed note paper using contacts provided from General Practices. Ninety percent of recruitment was achieved using this method. Adequate recruitment is fundamental to the success of a research project, and appropriate strategies must therefore be adopted in order to identify eligible individuals and achieve recruitment targets.

Trial registration number