Ethnic and gender differences in ambulatory blood pressure trajectories: results from a 15-year longitudinal study in youth and young adults.

BACKGROUND Cross-sectional studies demonstrated ethnic and gender differences in ambulatory blood pressure patterns, but little is known about the longitudinal development of these differences. METHODS AND RESULTS Twenty-four-hour ambulatory blood pressure was measured up to 12 times (5 times on average) over a 15-year period in 312 African Americans (AAs) and 351 European Americans aged 7 to 30 years. Multivariate individual growth curves across age were created for daytime and nighttime blood pressure jointly. For both daytime and nighttime systolic blood pressure (SBP), AAs and males had higher levels (P<0.001) than European Americans and females. Males also showed a greater increase with age (P<0.001) than females. For nighttime SBP, a faster increase of SBP with age (P<0.01) in AAs was additionally observed. The ethnic difference in nighttime SBP levels and its increase with age were significantly larger than in daytime SBP. For daytime and nighttime diastolic blood pressure, AAs had higher levels than European Americans (P<0.001), and this difference was significantly larger at night. From late adolescence onward, males showed a greater increase in diastolic blood pressure with age than females. Ethnic and gender differences persisted after adjustment for height, body mass index, socioeconomic status, and stress-related coping styles. Family history of essential hypertension explained ethnic differences in daytime SBP. CONCLUSIONS We observed significant ethnic and gender differences in longitudinal trajectories of ambulatory blood pressure in youth and young adults. The blunted nocturnal decline and its exacerbation with age in AAs corroborate and extend findings of cross-sectional studies.