Adolescents with dyslipidemia—especially those who were overweight or obese—were more likely than were adolescents with normal lipid levels to have increased carotid artery intima-media thickness by young adulthood, a study of 1,711 people found.
Also, the single set of cut points used in the National Cholesterol Education Program (NCEP) guidelines worked as well as the age- and sex-specific cut points derived from growth curve data in National Health and Nutrition Examination Surveys (NHANES) for predicting increased carotid intima-media thickness in young adults (J. Am. Coll. Cardiol. 2009;53:860–9 [doi:10.1016/j.jacc.2008.09.061]). The finding argues for using the simpler, fixed NCEP approach rather than the percentile-based NHANES approach, reported Costan G. Magnussen of the University of Tasmania (Australia).
Mr. Magnussen and his associates analyzed data from three large population-based, prospective cohort studies: the Finnish Cardiovascular Risk in Young Finns Study, the U.S.-based Bogalusa Heart Study, and the Australian Childhood Determination of Adult Health Study. Lipid and lipoprotein levels were measured in adolescents between the ages of 12 and 18 years and again when they were between the ages of 29 and 30 years, at which time they also had an ultrasound to measure carotid intima-media thickness, a surrogate for the risk of developing atherosclerosis.
In a previous analysis of this same data set, Mr. Magnussen and his associates found that adolescents with borderline or high-risk dyslipidemia were significantly more likely than were those with normal lipid levels to have dyslipidemia as adults after a mean follow-up of 20 years (Circulation 2008;117:32–42).
In the current study, adolescent dyslipidemia increased the relative risk for high intima-media thickness in adulthood by 60%–250%, and the higher risk was seen regardless of adult lipid and lipoprotein levels.
Adult carotid intima-media thickness was substantially higher in those who had been overweight or obese adolescents with dyslipidemia. The investigators estimated that overweight or obese 15-year-olds with dyslipidemia would show a difference in intima-media thickness of 0.11 mm in males or 0.08 mm in females by age 35 years, compared with normal-weight 15-year-olds with normal cholesterol levels.
Increased intima-media thickness in young adulthood provides “a more solid end point than we've had before,” said Dr. Roberta Williams, who was not involved in the study.
“If you are overweight/obese and have abnormal lipid levels, it is highly likely that you are headed for real changes in your vascular bed as an adult,” said Dr. Williams, chair of pediatrics at the University of Southern California, Los Angeles. She said she has no conflicts of interest related to this topic.
The positive predictive value of adolescent dyslipidemia was low (ranging from 11% to 37% depending on weight and type of dyslipidemia), a fact that may be explained in part by normal adolescent fluctuations in levels of lipoproteins, which are “building blocks'” for some hormones, she said. As a result, it's hard to tell which adolescents with dyslipidemia will go on to have increased intima-media thickness.
But the study found a high negative predictive value (ranging from 81% to 90%), meaning that adolescents without dyslipidemia are unlikely to develop cardiovascular disease as young adults.
In an editorial commenting on the study, Dr. Stephen R. Daniels noted that the findings do not settle the question of whether all adolescents or targeted populations should be screened for dyslipidemia. Current guidelines recommend screening based on family history or the presence of other risk factors such as obesity, diabetes, or hypertension.
The study addresses neither the morbidity and mortality outcomes after adolescent dyslipidemia is identified, nor the costs or acceptability of screening, noted Dr. Daniels, professor and chairman of pediatrics at the University of Colorado at Denver (J. Am. Coll. Cardiol. 2009;53:870–1 [doi:10.1016/j.jacc.2008.11.037]).
Dr. Magnussen reported no conflicts of interest related to this study. Dr. Daniels has been a consultant for Abbott Laboratories and Merck/Schering-Plough Pharmaceuticals, which market anticholesterol medications.
Obese teens with abnormal lipid levels are likely headed for real changes in their vascular beds as adults. DR. WILLIAMS