Skip to main content
Article thumbnail
Location of Repository

Explaining the effects of an intervention designed to promote evidence-based diabetes care : a theory-based process evaluation of a pragmatic cluster randomised controlled trial

By Jillian Joy Francis, Martin P. Eccles, Marie Johnston, Paula Whitty, Jeremy M. Grimshaw, Eileen F.S. Kaner, Liz Smith and Anne Walker


Background\ud The results of randomised controlled trials can be usefully illuminated by studies of the processes by which they achieve their effects. The Theory of Planned Behaviour (TPB) offers a framework for conducting such studies. This study used TPB to explore the observed effects in a pragmatic cluster randomised controlled trial of a structured recall and prompting intervention to increase evidence-based diabetes care that was conducted in three Primary Care Trusts in England.\ud \ud Methods\ud All general practitioners and nurses in practices involved in the trial were sent a postal questionnaire at the end of the intervention period, based on the TPB (predictor variables: attitude; subjective norm; perceived behavioural control, or PBC). It focussed on three clinical behaviours recommended in diabetes care: measuring blood pressure; inspecting feet; and prescribing statins. Multivariate analyses of variance and multiple regression analyses were used to explore changes in cognitions and thereby better understand trial effects.\ud \ud Results\ud Fifty-nine general medical practitioners and 53 practice nurses (intervention: n = 55, 41.98% of trial participants; control: n = 57, 38.26% of trial participants) completed the questionnaire. There were no differences between groups in mean scores for attitudes, subjective norms, PBC or intentions. Control group clinicians had 'normatively-driven' intentions (i.e., related to subjective norm scores), whereas intervention group clinicians had 'attitudinally-driven' intentions (i.e., related to attitude scores) for foot inspection and statin prescription. After controlling for effects of the three predictor variables, this group difference was significant for foot inspection behaviour (trial group × attitude interaction, beta = 0.72, p < 0.05; trial group × subjective norm interaction, beta = -0.65, p < 0.05).\ud \ud Conclusion\ud Attitudinally-driven intentions are proposed to be more consistently translated into action than normatively-driven intentions. This proposition was supported by the findings, thus offering an interpretation of the trial effects. This analytic approach demonstrates the potential of the TPB to explain trial effects in terms of different relationships between variables rather than differences in mean scores. This study illustrates the use of theory-based process evaluation to uncover processes underlying change in implementation trials.European Union ReBEQI projec

Topics: Diabetes Mellitus, Evidence-Based Practice, Randomised Controlled Trial
Publisher: BMC
Year: 2008
OAI identifier:

Suggested articles


  1. (2004). Constructing questionnaires based on the theory of planned behaviour. A manual for health services researchers. University of Newcastle upon Tyne: Centre for Health Services Research;
  2. Diabetes Mellitus Care. In Closing the Quality Gap: a critical analysis of quality improvement strategies.
  3. (1998). Diabetes Study (UKPDS) Group: Intensive bloodglucose control with sulphonylureas or insulin compared to conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet
  4. (2006). Do self-reported intentions predict clinicians' behaviour: a systematic review. Implement Sci
  5. (2004). Improving services for people with diabetes: lessons from setting up the DREAM trial. Practical Diabetes International
  6. (2006). L: A cluster randomised controlled trial of a Diabetes Recall and Management system: the DREAM trial.
  7. (2001). Salient beliefs and intentions to prescribe antibiotics for patients with a sore throat.
  8. (1995). The Acropolis Affirmation: Diabetes Care – St Vincent in Progress. Statement from the Saint Vincent Declaration meeting,
  9. (1991). The Theory of Planned Behavior. Organ Behav Hum Decis Process
  10. (1996). The Theory of Planned Behaviour: A Review of Its Applications to Health-related Behaviours.

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.