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Updated: Jul 3, 2026

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition
Published on: September 20, 2019
Development of a complex intervention improved randomization and informed consent in a randomized controlled trial
Jenny L Donovan1, J Athene Lane, Tim J Peters
1Department of Social Medicine, University of Bristol, Bristol BS8 2PR, UK. jenny.donovan@bristol.ac.uk
Objective:
Multicenter randomized trials are required for pragmatic evaluations of health care interventions, but recruitment is difficult. Systematic reviews failed to identify robust strategies to improve recruitment. We developed and evaluated a complex intervention to increase levels of randomization and informed consent.
Study Design And Setting:
The ProtecT (Prostate testing for cancer and Treatment) trial compares radical surgery, radical conformal radiotherapy, and active monitoring for men aged 50-69 years with localized prostate cancer. The intervention was developed using qualitative research methods (content, thematic and conversation analysis). Rates of randomization and immediate acceptance of allocation were measured every 6 months to evaluate the impact of the intervention.
Results:
The complex intervention comprised reviews of centers falling below study targets, training programmes, documents and individually tailored feedback. Over 65% of eligible participants consented to randomization. Trial participants became increasingly well informed as immediate acceptance of allocation rose from 65% to 81% between 2001 and 2005.
Conclusion:
This complex intervention resulted in high levels of randomization and informed consent in a difficult trial. The generic aspects of the intervention could be applied to other trials to maximize randomization and informed consent, and allow the mounting of trials previously considered too difficult.
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