Carotid intima‐media thickness predicts carotid plaque development: Meta‐analysis of seven studies involving 9341 participants

BACKGROUND: Carotid intima‐media thickness and carotid plaque are well‐established imaging markers used to capture different stages of the atherosclerotic disease process. We aimed to quantify to which extent carotid intima‐media thickness predicts incidence of first‐ever carotid plaque. MATERIALS AND METHODS: Two independent reviewers conducted a comprehensive literature search of PubMed and Web of Science. To be eligible for inclusion, prospective studies were required to involve participants free of carotid plaque at baseline and report on the association of baseline carotid intima‐media thickness with development of first‐ever carotid plaque. Study‐specific relative risks and 95% confidence intervals were collected and pooled using random‐effects meta‐analysis. RESULTS: We identified seven relevant prospective studies involving a total of 9341 participants. Individuals were recruited between 1987 and 2012, average age at baseline was 54 years, and 63% were female. Studies reported on 1288 incident first‐ever carotid plaques, occurring over an average maximum follow‐up of 8.7 years. When individuals in the top fourth of baseline carotid intima‐media thickness distribution were compared with those in the bottom fourth, the pooled relative risk for incidence of first‐ever carotid plaque was 1.78 (95% confidence interval: 1.53‐2.07, P < .001, I (2) = 2.8%). The strength of association was not modified by mean baseline age, proportion of female participants, length of follow‐up, year of baseline, and geographical location of the studies. CONCLUSIONS: In general population studies, elevated baseline carotid intima‐media thickness is associated with incidence of carotid plaque in individuals free of carotid plaque at baseline.