Open Access Highly Accessed Open Badges Research

Intervention description is not enough: evidence from an in-depth multiple case study on the untold role and impact of context in randomised controlled trials of seven complex interventions

Mary Wells1*, Brian Williams2, Shaun Treweek3, Joanne Coyle4 and Julie Taylor15

Author Affiliations

1 School of Nursing and Midwifery, University of Dundee, 11 Airlie Place, Dundee, DD1 4HJ, UK

2 Nursing, Midwifery and Allied Health Professions Research Unit, Iris Murdoch Building, University of Stirling, Stirling, FK9 4LA, UK

3 Population Health Sciences, School of Medicine, University of Dundee, The Mackenzie building, Kirsty Semple Way, Dundee, DD2 4BF, UK

4 Social Dimensions of Health Institute, University of St Andrews and University of Dundee, 11 Airlie Place, Dundee, DD1 4HJ, UK

5 National Society for the Prevention of Child Abuse and Neglect (NSPCC), Weston House, 42 Curtain Rd, London, EC2A 3NH, UK

For all author emails, please log on.

Trials 2012, 13:95  doi:10.1186/1745-6215-13-95

Published: 28 June 2012



A number of single case reports have suggested that the context within which intervention studies take place may challenge the assumptions that underpin randomised controlled trials (RCTs). However, the diverse ways in which context may challenge the central tenets of the RCT, and the degree to which this information is known to researchers or subsequently reported, has received much less attention. In this paper, we explore these issues by focusing on seven RCTs of interventions varying in type and degree of complexity, and across diverse contexts.


This in-depth multiple case study using interviews, focus groups and documentary analysis was conducted in two phases. In phase one, a RCT of a nurse-led intervention provided a single exploratory case and informed the design, sampling and data collection within the main study. Phase two consisted of a multiple explanatory case study covering a spectrum of trials of different types of complex intervention. A total of eighty-four data sources across the seven trials were accessed.


We present consistent empirical evidence across all trials to indicate that four key elements of context (personal, organisational, trial and problem context) are crucial to understanding how a complex intervention works and to enable both assessments of internal validity and likely generalisability to other settings. The ways in which context challenged trial operation was often complex, idiosyncratic, and subtle; often falling outside of current trial reporting formats. However, information on such issues appeared to be available via first hand ‘insider accounts’ of each trial suggesting that improved reporting on the role of context is possible.


Sufficient detail about context needs to be understood and reported in RCTs of complex interventions, in order for the transferability of complex interventions to be assessed. Improved reporting formats that require and encourage the clarification of both general and project-specific threats to the likely internal and external validity need to be developed. In addition, a cultural change is required in which the open and honest reporting of such issues is seen as an indicator of study strength and researcher integrity, rather than a symbol of a poor quality study or investigator ability.

RCT; Case study; Context; Complex interventions