Birth cohort evidence of population influences on blood pressure in the United States, 1887-1994.
OBJECTIVE
Mean blood pressure (BP) has declined in the U.S. for several decades. It is unknown to what extent this decline was due to treatment of persons with recognized high BP or to population-wide influences on BP. Treatment would shift only the highest values lower, whereas, population-wide influences 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 individuals examined in the National Health (and Nutrition) Examination Surveys between 1960 and 1994. The BP distributions were estimated as functions of age and birth-year to examine changes between birth cohorts. We postulated that the age-adjusted 10th, 50th and 90th percentiles of SBP and DBP had decreased in more recent versus earlier birth cohorts.


RESULTS
The series of birth cohorts exhibited successively lower SBP and DBP at low, middle and high percentiles. In general, the 10th percentile of SBP decreased approximately 1.19 mmHg per decade of birth-year, whereas the 50th percentile decreased 2.40 mmHg per decade, and the 90th percentile decreased 4.62 mmHg per decade. A similar pattern of results was seen for DBP.


CONCLUSIONS
The entire distribution of both SBP and DBP shifted downward. The downward shifts at the 50th percentile and below unequivocally demonstrate a strong prevention effect in the U.S. population during the period 1887 through 1975. This epidemiologic analysis indicates that population-wide influences can alter favorably the distribution of BP throughout the whole population.
Goff
D C
DC
Department of Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1063, USA.
Howard
G
G
Russell
G B
GB
Labarthe
D R
DR
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001794:Blood Pressure; D015331:Cohort Studies; D003327:Coronary Disease / Q000401:mortality; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D008875:Middle Aged; D012307:Risk Factors; D020521:Stroke / Q000401:mortality; D014481:United States / Q000453:epidemiology