Trends in Income Inequities in Cardiovascular Health Among US Adults, 1988–2018

Abstract

BACKGROUND: Mean cardiovascular health has improved over the past several decades in the United States, but it is unclear whether the benefit is shared equitably. This study examined 30-year trends in cardiovascular health using a suite of income equity metrics to provide a comprehensive picture of cardiovascular income equity. METHODS: The study evaluated data from the 1988–2018 National Health and Nutrition Examination Survey. Survey groupings were stratified by poverty-to-income ratio (PIR) category, and the mean predicted 10-year risk of a major cardiovascular event or death based on the pooled cohort equations (PCE) was calculated (10-year PCE risk). Equity metrics including the relative and absolute concentration indices and the achievement index—metrics that assess both the prevalence and the distribution of a health measure across different socioeconomic categories—were calculated. RESULTS: A total of 26 633 participants aged 40 to 75 years were included (mean age, 53.0–55.5 years; women, 51.9%–53.0%). From 1988–1994 to 2015–2018, the mean 10-year PCE risk improved from 7.8% to 6.4% ( P <0.05). The improvement was limited to the 2 highest income categories (10-year PCE risk for PIR 5: 7.7%–5.1%, P <0.05; PIR 3–4.99: 7.6%–6.1%, P <0.05). The 10-year PCE risk for the lowest income category (PIR <1) did not significantly change (8.1%–8.7%). In 1988–1994, the 10-year PCE risk for PIR <1 was 6% higher than PIR 5; by 2015–2018, this relative inequity increased to 70% ( P <0.05). When using metrics that account for all income categories, the achievement index improved (8.0%–7.1%, P <0.05); however, the achievement index was consistently higher than the mean 10-year PCE risk, indicating the poor persistently had a greater share of adverse health. CONCLUSIONS: In this serial cross-sectional survey of US adults spanning 30 years, the population’s mean 10-year PCE risk improved, but the improvement was not felt equally across the income spectrum.