The Canadian C-Spine Rule and CT-Head Rule Implementation Studies: A Psychological Process Evaluation

Abstract

The Canadian C-Spine (CS) and CT-Head (CT) Rules are tools aimed at improving the accuracy and efficiency of radiography use in emergency departments. This study evaluated whether the Theory of Planned Behaviour (TPB) could explain the inconsistent results from implementation studies of these two rules at 12 Canadian hospitals, where the same intervention resulted in a significant reduction in CS radiography but not CT radiography. It was demonstrated that the TPB model’s proposed relationships between constructs and behaviour could explain the ordering of CS but not CT radiography. However, after examining longitudinal changes of the TPB constructs, it was clear that these changes could not explain the changes in CS radiography ordering. Overall, TPB is unlikely to suggest important ways by which to improve radiography use, for CT because its constructs are not related to radiography ordering, and for CS because of high baseline levels of intention to clinically clear.