Background: It is unknown whether the previously recognized disparities in cardiovascular disease (CVD) risk factors related to annual income and educational level have diminished, persisted, or worsened in recent decades. The objective of this study was to examine 31-year trends in CVD risk factors by annual income and educational levels among US adults.
Methods: Four cross-sectional national surveys were used: National Health and Nutrition Examination Survey I (1971-1974), II (1976-1980), III (1988-1994), and 1999-2002. The main outcome measure was prevalence of high cholesterol (> or =240 mg/dL [> or =6.2 mmol/L]), high blood pressure (140/90 mm Hg), smoking, and diabetes mellitus.
Results: Between 1971 and 2002, the prevalence of all CVD risk factors, except diabetes, decreased in all income and education groups, but there has been little reduction in income- and education-related disparities in CVD risk factors and few improvements during the past 10 years. The prevalence of high blood pressure declined by about half in all income and education groups, ranging from 30.3% to 40.6% in 1971-1974 and 16.4% in 1999-2002, with the greatest reduction among those in the lowest income quartile and those with less than a high school education (18.0 and 15.9 percentage points, respectively). High cholesterol prevalence also declined in all groups and ranged from 28.8% to 32.4% in 1971-1974 and 15.3% to 22.0% in 1999-2002, with the largest decline (15.9 percentage points) among people with the highest incomes. Education- and income-related disparities in smoking widened considerably, because there were large declines in smoking prevalence among people with high incomes and education (from about 33% in 1971-1974 to about 14%-17% in 1999-2002) but only marginal reductions among those with low incomes and education (about 6-percentage point decline). Diabetes prevalence increased most among persons with low incomes and education.
Conclusions: Despite the general success in reducing CVD risk factors in the US population, not all segments of society are benefiting equally and improvements may have slowed. Education- and income-related disparities have worsened for smoking, and increases in diabetes prevalence have occurred primarily among persons with a lower socioeconomic status. Diabetes prevention and smoking prevention and cessation programs need to specifically target persons of lower income and education.