WEDNESDAY, July 20 (HealthDay News) -- The maximum intima-media thickness of the internal carotid artery contributes significantly, but modestly, toward improvement in cardiovascular event risk classification based on the Framingham risk score, according to a study published in the July 21 issue of the New England Journal of Medicine.
Joseph F. Polak, M.D., M.P.H., from Tufts Medical Center in Boston, and colleagues investigated whether the mean and maximum intima-media thickness of common and internal carotid artery, respectively, added to the Framingham risk score's predictive value for cardiovascular events in 2,965 participants of the Framingham offspring study. Participants were followed up for an average of 7.2 years. Hazard ratios were calculated for intima-media thickness and risk factors. Cardiovascular disease was reclassified after adding intima-media thickness values to the eight-year Framingham risk score category (low, intermediate, or high).
The investigators found that cardiovascular events occurred in 296 participants, which were predicted by the risk factors of the Framingham risk score, with a C statistic of 0.748. The adjusted hazard ratio for cardiovascular disease with one standard deviation increase in common carotid mean intima-media thickness was 1.13 with nonsignificant C statistic (0.003). The corresponding result for maximum intima-media thickness was a hazard ratio of 1.21, with modestly increased C statistic (0.009). Net reclassification index showed a significant increase after adding internal carotid intima-media thickness (7.6 percent) but not common carotid artery intima-media thickness. For internal carotid intima-media thickness of more than 1.5 mm (presence of plaque), net reclassification index was 7.3 percent, with an increase in the C statistic of 0.014.
"Only the maximum intima-media thickness of (and presence of plaque in) the internal carotid artery significantly (albeit modestly) improves the classification of risk of cardiovascular disease," the authors write.
One of the study authors disclosed a financial relationship with Abbott.
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