CUHK electronic theses & dissertations collection

Background and objective. Ultrasonic evaluation of carotid intima media thickness (IMT) has been widely used as a surrogate of atherosclerosis. Few studies have specifically examined risk factors related to subclinical atherosclerosis (SA) among early postmenopausal women, in particular in the Chinese population. There is also little information on the distribution of IMT in Asian midlife women. We described the prevalence of SA, as determined by IMT and carotid plaque, and the associated risk factors in early postmenopausal Chinese women in Hong Kong.Conclusions. Our findings showed that age, SBP, HDL-C, and LDL-C were independent predictors of IMT, while age, LDL-C, and abdominal obesity were independent predictors of the presence of plaque. The optimal IMT cutoff of 0.783 mm was defined and that a prevalence of SA (IMT ≥ 0.783 mm) of 38.6% was found among 'healthy' early postmenopausal Chinese women in Hong Kong.Methods. 518 women aged 50 to 64 years, and within 10 years since menopause were recruited from random telephone dialing. Women with surgical menopause, established cardiovascular diseases (CVD), and severe disease conditions such as cancer and renal failure were excluded. Sociodemographic, anthropometric and lifestyle factors were obtained based on standardized questionnaires. Fasting blood sample was also obtained. B-mode ultrasound was used for measuring IMT at 12 sites of the carotid arteries and plague index, which is the sum of the grades (ranged from 0 to 3) at the 6 segments. The relations between traditional risk factors, and other potential risk factors such as inflammatory markers, as well as lifestyle factors including physical activity, dietary intake, and psychological factors with SA were also assessed.Results. The mean IMT +/- SD was 0.76 +/- 0.12 mm, with a range from 0.53 to 1.00 mm. IMT was higher on the far wall than on the near wall (P<0.01), and differ among segments (greatest at the bulb and least at the ICA) (P<0.01). One-fifth of women had at least 1 plaque in the carotid artery with most of the plaque occurred in the bulb area. IMT increased with age, and was positively associated with carotid plaque. With the use of receiver operating characteristic curve (ROC) analysis, the optimal cutoff IMT for diagnostic plaque was 0.783 mm, at which sensitivity and specificity was 80.5% and 75.1%, respectively. The prevalence of SA was 38.6%. Among the traditional risk factors, systolic blood pressure (SBP), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C) were associated with high IMT. Abdominal obesity assessed by waist circumference (WC) and waist hip ratio (WHR) was also found to be positively associated with IMT. Stepwise multiple regression showed that age, SBP, HDL-C, and LDL-C were independent predictors of IMT. Multiple logistic regression showed that women with LDL-C ≥ 130 mg/dL were associated with a 2.4-fold (95% CI 1.5-3.7) higher risk of having plaque compared to those with LDL-C < 130 mg/dL. In addition, women with abdominal obesity (WHR ≥ 0.85) had a 1.7-fold (95% CI 1.08-2.67) higher risk of having plaque than women with WHR < 0.85 after adjustment for age, and potential confounders including physical activity, dietary intakes etc. Significant inverse associations were observed between physical activity and indices of obesity, as well as fasting blood glucose, while psychological perceived stress and trait anxiety were independent risk factors for both total cholesterol and LDL-C.Yu Ho-yan."February 2006."Adviser: Suzanne C. Ho.Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6350.Thesis (Ph.D.)--Chinese University of Hong Kong, 2006.Includes bibliographical references (p. 220-256).Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Abstracts in English and Chinese.School code: 1307