Birth cohort evidence of population influences on blood pressure in the United States, 1887-1994

PURPOSE: Mean blood pressure (BP) has declined in the U.S. for several deca des. It is unknown to what extent this decline was due to treatment of pers ons with recognized high BP or to population-wide influences on BP. Treatme nt would shift only the highest values lower, whereas, population-wide infl uences on BP would shift the entire distribution downward. METHODS: We examined changes in the distributions of systolic and diastolic BP (SBP, DBP) across birth cohorts born between 1887 and 1975 in 52,646 in dividuals examined in the National Health (and Nutrition) Examination Surve ys between 1960 and 1994. The BP distributions were estimated as functions of age and birth-year to examine changes between birth cohorts. We postulat ed that the age-adjusted 10th, 50th and 90th percentiles of SEP and DBP had decreased in more recent versus earlier birth cohorts. RESULTS: The series of birth cohorts exhibited successively lower SEP and D BP at low, middle and high percentiles. In general, the 10th percentile of SEP decreased approximately 1.19 mmHg per decade of birth-year, whereas the 50th percentile decreased 2.40 mmHg per decade, and the 90th percentile de creased 4.62 mmHg per decade. A similar pattern of results was seen for DBP . CONCLUSIONS: The entire distribution of both SEP and DBP shifted downward. The downward shifts at the 50th percentile and below unequivocally demonstr ate a strong prevention effect in the U.S, population during the period 188 7 through 1975. This epidemiologic analysis indicates that population-wide influences can alter favorably the distribution of BP throughout the whole population. Ann Epidemiol 2001;11:271-279. (C) 2001 Elsevier Science Inc. A ll rights reserved.