Sex-Specific Differences in the Association Between Metabolic Syndrome and Carotid Intima-Media Thickness Among a Low-Income Population in China: A Cross-Sectional Study

Introduction: Carotid atherosclerosis is a well-established biomarker associated with future cardiovascular disease and stroke. We explored the influence of sex on the relationship between metabolic syndrome (MetS) and its components with carotid intima-media thickness (CIMT) among a low-income population in China, which has a high incidence of stroke. Methods: This population-based study recruited participants aged >= 45 years from rural areas of Tianjin, China between April 2014 and January 2015. Anthropometric characteristics and biochemical profiles were measured. CIMT was assessed using ultrasonography. Diagnosis of MetS and its components was made using the modified International Diabetes Federation criteria for the Asian population. A multivariate linear regression model was used to evaluate the effects of sex on the relationship between the presence of MetS and its components and CIMT. Results: A total of 3583 individuals (men, 41.4%; women, 58.6%) were included in the analyses. MetS was prevalent in 54.5% (men, 42.3%; women, 63.2%) of the participants. Mean CIMT was 0.57 +/- 0.09 mm. In the multivariate analysis, for both sexes, CIMT increased significantly when MetS was present compared with when it was not (both P < 0.001). A common trend was observed in both sexes, in that CIMT increased as the number of MetS components increased, with beta (95% confidence interval [CI]) = 0.021 (0.000, 0.042) for men and 0.014 (0.002, 0.026) for women (both P < 0.05). Of the five MetS components, elevated blood pressure was an independent risk factor for increased CIMT in both sexes (men: beta = 0.013; 95% CI: 0.003, 0.023; P = 0.008; women: beta = 0.024; 95% CI: 0.016, 0.033; P < 0.001). Moreover, abdominal obesity was also an independent risk factor for increased CIMT in men (beta = 0.013; 95% CI: 0.003, 0.023; P = 0.008) but not in women. Conclusion: The presence and number of components of MetS were associated with CIMT in both men and women. Sex differences were found in the impact of individual components of MetS on CIMT. Early identification and management of MetS according to sex-specific risk of MetS should be considered to reduce the prevalence and burden of carotid atherosclerosis in rural China, which has a high incidence of stroke, a known consequence of carotid atherosclerosis.