1. In this prospective cohort study, the higher rate of hypertension in black patients than white patients was most strongly influenced by a Southern diet in both men and women.
2. Other dietary and socioeconomic factors were also associated with the increased incidence of hypertension in black patients.
Evidence Rating Level: 2 (Good)
Study Rundown: The largest contributor to the difference in mortality between black and white populations in the US is cardiovascular health. The presence and severity of hypertension plays a large role in this difference, but the mediators for the differences in incident hypertension between black and white patients is unclear. In this prospective cohort study, the Southern diet was the largest mediator in the difference in the rates of incident hypertension between black and white patients for both men and women. For men, the sodium-to-potassium ratio and low educational attainment were less influential factors that mediated this difference. For women, BMI, waist circumference, sodium-to-potassium ratio, adherence to a DASH diet, low income, and lower educational attainment were also significant but less influential factors mediating this difference.
Though all the mediating factors are associated with hypertension in general, the conclusion that the Southern diet is the largest mediating factor is of great interest. This raises the question of whether hypertension treatments would be better tailored to patients based on dietary patterns than race, especially for diuretics. The limitations of this study should be acknowledged and include follow-up of only about half of eligible patients and oversampling residents in the southeastern “stroke belt” region of the US.
In-Depth [prospective cohort]: 6897 black and white patients without hypertension were recruited to the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort from 2003 to 2007 and followed for a median of 9.4 years (follow-up rate 56%). At follow-up, the presence of hypertension as well as the presence of twelve mediating factors were assessed. Black participants in this study were younger, more likely to have an education level of high school or less, have an income of less than $35,000, and had higher prevalence of most factors associated with incident hypertension compared to white participants. Similar to other studies, black participants had a higher rate of incident hypertension for men (OR 1.35; CI95 1.12 to 1.61) and for women (OR 1.73 CI95 1.49 to 2.01). A Southern diet was found to be the largest mediating factor in incident hypertension in both men (51.6% of higher risk; CI95 18.8 to 84.4%) and women (29.2%; CI95 13.4 to 44.9%). For men, the sodium-to-potassium ratio (12.3%; CI95 1.1 to 22.8%) and having an education level of high school or less (12.3%; CI95 0.6 to 23.9%) were also influential factors that mediated this difference. For women, BMI (18.3%; CI95 11.9 to 24.6%), waist circumference (15.2%; CI95 9.8 to 20.6%), sodium-to-potassium ratio (6.8%), adherence to a DASH diet (11.2%), income of less than $35,000 (9.3%), and having an education level of high school or less (4.1%) were also significant influential factors mediating this difference.
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