INTIMA-MEDIA THICKNESS (IMT) IN ADOLESCENT GIRLS: A FOLLOW UP

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Carotid artery intima-media thickness (IMT) is an important predictor of cardiovascular disease in adults. Our previous study of bone density and hormonal contraception in girls aged 12-18 included a substudy of IMT of the carotid artery in these same subjects over 18 months. IMT data were obtained by B-mode ultrasound examination. Measurements of the distal 2-cm of the right common carotid artery were obtained in 3 planes and averaged for a composite score. Repeated measures analysis of covariance was conducted with the IMT score to explore the relationships among contraceptive methods, time, and IMT adjusting for race, age, and weight. The sample was comprised of 53 controls, 22 DMPA, and 50 OC subjects who completed baseline data for a total of 125 participants. Six-month data were available for 115 subjects, 12-month data for 96 subjects, and 18-month data for 44 subjects. At 6 month intervals, the participants had measurement of IMT, height, weight, blood pressure, total and HDL cholesterol, and were questioned about smoking status. No statistically significant difference was found in IMT score between contraceptive groups or with regards to low and high BMI, blood pressure, smoking status, total or HDL cholesterol. However, there was a steady decrease in the IMT score averaged across groups over time (p=0.01). The mean IMT for all groups at baseline was 0.47mm (SE 0.0038) At 18 months the mean IMT was 0.44 mm (SE 0.0079), a 6.4% decrease of IMT in 18 months. Our previous study suggests that the hormonal environment during this period of development may have a favorable effect on this expression of cardiovascular status. An additional inference is that hormonal contraception may not be a key component contributing to these changes. Therefore, in order to confirm our findings of a decrease in IMT over time, it is important to obtain one additional IMT measurement from a subgroup of our substudy sample. The same IMT measurement will be obtained from approximately 22 control subjects who are still under the age of 18. Serum will collected and analyzed for total and HDl cholesterol, height, weight, smoking history, interval health history, and a pregnancy urine test.