Risk of Bias in Health Behaviour Change Trials: Evidence, Practices and Challenges


  • M. Johnston
  • M. de Bruin


Aims: To discuss the various sources of bias in health behaviour change (HBC) RCTs; causes and strategies to overcome these; and how to proceed and enhance the quality of the evidence-base of HBC interventions. Background: Results from randomized controlled trials (RCTs) can be threatened by multiple sources of bias. Reviews suggest that behavioural trials have a relatively high risk of bias. It is largely unclear whether this is due to poor trial design, incomplete trial reports, or because instruments for assessing the risk of bias do not map well on health behaviour change trials. Summary: We will present the studies include in a special issue of Psychology and Health. An overview will be provided on sources of bias and strategies for reducing the risk of bias in RCTs evaluating the effectiveness or cost-effectiveness of interventions of interventions. Two speakers will examine specific sources of bias, namely differential attrition and content/context of controls groups. Finally, after a brief overview of the results of the complete special issue, all speakers contribute to a discussion on how to proceed to enhance the quality of the evidence-base provided by HBC RCTs.