Age-adjusted reference limits for carotid intima-media thickness as better indicator of vascular risk: population-based estimates from the VITA project.

Abstract

An increase of carotid intima-media thickness (CIMT) has been demonstrated to be associated in many studies with the subsequent risk of cardio- and cerebrovascular events, but the threshold level of CIMT for an increased risk at different ages remains uncertain. We aimed at establishing optimal reference limits associated with a definite increased vascular risk in the general population. A cohort of 2580 subjects was enrolled in a population-based cross-sectional survey. CIMT was measured on both left and right common carotid arteries, and age-specific, percentile-based reference ranges for CIMT were computed together with the Framingham risk score. A significant, steady increase of CIMT reference ranges was observed within different age strata. CIMT levels were linearly related with an increase of the Framingham risk score, but after age-adjustment only the upper CIMT quintile was associated with a higher Framingham risk score. Age-specific reference limits provide better estimate of vascular risk in the population and correlation with established risk factors.