Introduction:
Health disparities remain pervasive in US and eliminating such disparities is one of the overarching goals of the Healthy People 2020 agenda. Previous studies have assessed the disparities in risk of coronary heart disease (CHD) mortality by race/ethnicity, but most of them only focused on the average CHD risk without taking into account the full risk distribution which would enable analysis of specific high-risk sub-groups. In this study, we estimated the 10-year risk distribution of CHD mortality based on 5 leading modifiable risk factors in US (i.e. smoking, adiposity, high blood pressure, serum cholesterol and blood glucose). We quantified the racial disparities in absolute CHD risk while accounting for full risk distribution.
Methods:
We included 3866 individuals aged 45 to 74 years, who were black or white, non-pregnant, free of CHD and had measurements of all 5 risk factors from 6 consecutive 2-year cycles of the National Health and Nutrition Examination Survey 1999-2010. We used mortality data from National Center for Health Statistics to estimate the cause-age-sex-race specific mortality in 2010. We also obtained hazard ratios of the selected 5 risk factors on CHD mortality from large meta-analyses of epidemiological studies. We predicted the 10-year risk of CHD death for each individual by simulating their survival process from 2010 to 2020 incorporating competing risks by death from other correlated causes. To assess health disparities, we compared the 5
th
, 25
th
, 50
th
, 75
th
and 95
th
percentile of the predicted risks between black and white by age and sex.
Results:
More than half of the black and white population aged 45 to 74 years had a low 10-year risk of CHD death (< 2%). The age-sex-race specific distributions of 10-year CHD risk were right-skewed with a large proportion of population on the low risk tail. Comparing to white, black had similar shape of CHD risk distributions, but higher risk levels at all percentiles across age and sex groups. In 55-64 ages where CHD was the major cause of death, the median of CHD risk for black males was 2.9% (interquartile range (IQR) 1.7% - 4.4%), which was 0.7% larger than that for white males (2.2%, IQR 1.4% - 3.3%). This risk difference was similar in females: the median CHD risk for black females was 1.6% (IQR 0.9% - 2.4%) and 0.9% for white females (IQR 0.5% - 1.5%). The disparities became larger on the high risk tail (95
th
percentile of predicted risk), where black had 2.7% higher risk for male and 2.3% for female in 55-64 ages. In older age groups (65-74 ages), such difference increased to 3.5% for both male and female.
Conclusions:
This analysis showed a skewed 10-year CHD risk distribution in US. The racial disparities are larger in the high risk sub-groups compared to those in the center of the risk distribution, indicating that the high risk subgroups should be the target population of intervention that aims to reduce health disparities in US.
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