Process evaluation of complex cardiovascular interventions: How to interpret the results of my trial?

Complex interventions of varying degrees of complexity are commonly used and evaluated in cardiovascular nursing and allied professions. Such interventions are increasingly tested using randomized trial designs. However, process evaluations are seldom used to better understand the results of these trials. Process evaluation aims to understand how complex interventions create change by evaluating implementation, mechanisms of impact, and the surrounding context when delivering an intervention. As such, this method can illuminate important mechanisms and clarify variation in results. In this article, process evaluation is described according to the Medical Research Council guidance and its use exemplified through a randomized controlled trial evaluating the effectiveness of a transition program for adolescents with chronic conditions.