Importance of socioeconomic status as a predictor of cardiovascular outcome and costs of care in women with suspected myocardial ischemia. Results from the National Institutes of Health, National Heart, Lung and Blood Institute-sponsored Women's Ischemia Syndrome Evaluation (WISE)

Abstract

Background: For women, who are more likely to live in poverty, defining the clinical and economic impact of socioeconomic factors may aid in defining redistributive policies to improve healthcare quality.

Methods: The NIH-NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE) enrolled 819 women referred for clinically indicated coronary angiography. This study's primary end point was to evaluate the independent contribution of socioeconomic factors on the estimation of time to cardiovascular death or myocardial infarction (MI) (n = 79) using Cox proportional hazards models. Secondary aims included an examination of cardiovascular costs and quality of life within socioeconomic subsets of women.

Results: In univariable models, socioeconomic factors associated with an elevated risk of cardiovascular death or MI included an annual household income <$20,000 (p = 0.0001), <9th grade education (p = 0.002), being African American, Hispanic, Asian, or American Indian (p = 0.016), on Medicaid, Medicare, or other public health insurance (p < 0.0001), unmarried (p = 0.001), unemployed or employed part-time (p < 0.0001), and working in a service job (p = 0.003). Of these socioeconomic factors, income (p = 0.006) remained a significant predictor of cardiovascular death or MI in risk-adjusted models that controlled for angiographic coronary disease, chest pain symptoms, and cardiac risk factors. Low-income women, with an annual household income <$20,000, were more often uninsured or on public insurance (p < 0.0001) yet had the highest 5-year hospitalization and drug treatment costs (p < 0.0001). Only 17% of low-income women had prescription drug coverage (vs. >or=50% of higher-income households, p < 0.0001), and 64% required >or=2 anti-ischemic medications during follow-up (compared with 45% of those earning >or=$50,000, p < 0.0001).

Conclusions: Economic disadvantage prominently affects cardiovascular disease outcomes for women with chest pain symptoms. These results further support a profound intertwining between poverty and poor health. Cardiovascular disease management strategies should focus on policies that track unmet healthcare needs and worsening clinical status for low-income women.

FIG. 1.

Estimated metabolic equivalents (METs) (average ± SD) by the Duke Activity Status Index (DASI) at baseline through 5 years of follow-up by household income <$20,000, $20,000–$49,999, $50,000–$99,999, and ≥$100,000, respectively. The line of best-fit between baseline and through 5 years of follow-up was fit with a polynomial function.

FIG. 2.

Survival free from cardiovascular (CV) death or nonfatal myocardial infarction (MI) by annual household income of <$20,000, $20,000–$49,999, $50,000–$99,999, and ≥$100,000, respectively.

FIG. 3.

Survival free from cardiovascular (CV) death or nonfatal myocardial infarction (MI) by education, including women attending school prior to high school, those having some high school education, and those having some post-high school training, respectively. GED, General Educational Development diploma.

FIG. 4.

Survival free from hospitalization for worsening chest pain symptoms by household income. (Lines for≥$100,000 were superimposed over $50,000–$99,999 lines and were thus merged for this analysis.)

FIG. 5.

Use of cardiac procedures during follow-up, including repeat coronary angiography and coronary revascularization procedures [percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABS)] and recorded use of two or more anti-ischemic medications during follow-up. CV, cardiovascular.

FIG. 6.

Five-year hospital (p < 0.0001) and drug (p < 0.0001) costs by annual household income. Also included are 5-year indirect costs, which were similar across household incomes (p = 0.76). All cost estimates were adjusted for the DASI estimate of MET capacity as a surrogate for disability. Further risk adjustment using age and angiographic coronary disease did not change these results.