Low socioeconomic status over 12 years and subclinical cardiovascular disease: the study of women's health across the nation

Abstract

Background and purpose: The inverse relation between socioeconomic status and cardiovascular disease is well established. However, few studies have investigated socioeconomic status assessed repeatedly during adulthood in relation to subclinical atherosclerosis. We aimed to test whether consistently low socioeconomic status, as indexed by education, income, and financial strain, for 12 years of midlife was related to later carotid intima-media thickness and plaque among women.

Methods: The Study of Women's Health Across the Nation is a multisite longitudinal study of midlife women. Education was assessed at the study baseline, income and financial strain were obtained yearly for 12 years, and a carotid ultrasound was obtained at study year 12 among 1402 women. Associations were tested in linear and multinomial logistic regression models adjusted for demographic, biological, and behavioral risk factors.

Results: A high school education or less (odds ratio [OR] [95% confidence interval {CI}], 1.72 [1.15-2.59]; P<0.01), some college education (OR [95% CI], 1.65 [1.17-2.32]; P<0.01), consistently low income (OR [95% CI], 1.83 [1.15-2.89]; P<0.05), and consistent financial strain (OR [95% CI], 1.78 [1.21-2.61]; P<0.01) for 12 years were associated with higher carotid plaque, and consistent financial strain was associated with elevated maximal intima-media thickness (β [SE]=0.02 [0.01]; P<0.05) controlling for standard cardiovascular disease risk factors. When socioeconomic status indices were considered together, financial strain (β [SE]=0.02 [0.01]; P<0.05) and low education (high school education or less: OR [95% CI], 1.55 [1.01-2.37]; P<0.05; some college: OR [95% CI], 1.56 [1.09-2.21]; P<0.05) were most consistently associated with intima-media thickness and plaque, respectively, controlling for risk factors.

Conclusions: The findings indicate the importance of targeting economically disadvantaged women in efforts to prevent cardiovascular disease among women.

Keywords: atherosclerosis; cardiovascular diseases; carotid intima-media thickness; education; social class.