Rate of change in carotid intima-media thickness and vascular events: meta analyses can not solve all the issues. A point of view

Whether a change in the rate of carotid intima-media thickness (CIMT) over time that is induced by a pharmaceutical intervention can be directly translated into change in future cardiovascular disease risk is an important issue. As this biomarker is increasingly used as primary outcome in many trials of the evaluation of novel cardiovascular treatments, this has become an important topic in cardiovascular drug development. Two recent meta-analyses using aggregated data from publication have attempted to address the issue. In our view both analyses suffer from considerable flaws. Flaws include the misuse of the concept of the atherosclerosis, pooling of trials carried out with treatments of heterogeneous efficacy and in patients, who had very different risk profiles; pooling of measurements from a wide variety of methodologies that shared a common name, 'CIMT'; lack of power for detecting relationships using meta-regression techniques, and lastly, the ecologic fallacy. In this article, we discuss the concerns in more detail and offer strategies to get a valid answer on whether therapy-induced change in CIMT indeed relates to change in vascular risk.