Divergence with age in blood pressure in African-Caribbean and white populations in England: implications for screening for hypertension.

BACKGROUND: We assessed when blood pressure (BP) and hypertension begin to rise in African-Caribbeans compared to the white population; and whether the change relates to body mass index (BMI).
METHODS: Secondary analysis of the cross-sectional Health Surveys for England among 22,723 participants (21,344 whites and 1,379 African-Caribbeans) adults aged ≥18 years.
RESULTS: The cubic spline graphs showed a crossover (African-Caribbean greater than whites) at 30-40 years in BP. Age-specific mean BP and hypertension prevalence data showed at 20-29 years African-Caribbean men were advantaged but not thereafter. There was little difference in BMI in men. African-Caribbean women had lower systolic BP (but higher prevalence of hypertension) at 20-29 years but higher BP and prevalence of hypertension thereafter. African-Caribbean women had higher BMI than white women. Regression showed an age and ethnicity interaction for systolic (0.076 mm Hg greater increase per year, P = 0.054) and diastolic BP (0.068 mm Hg greater increase per year (P = 0.009) and hypertension (OR equals 1.02, P = 0.004) in African-Caribbean men, and diastolic BP in African-Caribbean women (0.057 mm Hg greater increase per year, P = 0.017). Crossover was 28, 44, and 28 years for systolic BP, diastolic BP and hypertension in men, respectively; and 40 years for diastolic BP in women.
CONCLUSIONS: Clinicians should be extra vigilant about screening African-Caribbean patients from the age of 30 years. Detailed study is needed to understand the still mysterious mechanisms for this crossover.