Objectives Few studies have assessed the utility of the Theory of Planned Behaviour (TPB) in explaining physicians' behaviour. This study uses the TPB for explaining physicians' implementation of guidelines' prescribing recommendations.
Methods We developed the questionnaire via conducting qualitative interviews and pilot study. A random sample of 155 general practitioners (GPs) in England participated in the study. Prescribing and practice data were collected from routine sources. We analysed the data using regression methods.
Results TPB explained 48% of variation in reported intentions to follow guidelines' prescribing recommendations. Attitude and perceived controls, but not subjective norms, were predictors of variation in intentions. TPB belief variables significantly explained variation in effective and efficient prescribing indicators (14% and 12% respectively). Normative, control and behavioural beliefs contributed to the models. Only for efficient prescribing, the TPB items retained their significance in presence of demographic variables. We found no significant relationship between intention and prescribing.
Conclusions TPB helped understanding of GPs prescribing behaviour and their intentions to implement a clinical guideline. Beliefs (e.g. normative beliefs) were better predictors of behaviour than the composite scores for their corresponding higher-level construct (e.g. indirect subjective norm). TPB models should be tested alongside randomized trials to test the assumption of causality that change in beliefs ultimately results in change in behaviour.