Decline in US stroke mortality. Demographic trends and antihypertensive treatment.

Stroke mortality has been falling rapidly in this country since 1973. To investigate age-race-sex effects on stroke mortality, we studied US vital statistics during 1950-1972 and 1973-1981 in 55-64-, 65-74-, and 75-84-year-old race-sex groups. The accelerated rate of decline in stroke mortality since 1973 has had a substantial public health impact, with greater than 200,000 fewer stroke deaths than would otherwise have occurred. For all groups, stroke mortality declined at a greater rate (p less than 0.05) in 1973-1981 than during 1950-1972. The rates of decline during 1973-1981 were greater with increasing age (p less than 0.05) and were more substantial for younger blacks. There were no consistent differences in the rate of decline by sex. The greater rate of decline in absolute stroke mortality in the older age groups and blacks was explained by higher baseline mortality in these groups. Overall, stroke mortality decreased by approximately 2%/yr in 1950-1972 and by approximately 7%/yr after 1973. Rank order of average annual percent decline after 1973 by age-race-sex groups did not correspond to rates of change in treatment or control of hypertension obtained from three national surveys. The accelerated rate of decline after 1973 may have resulted from improved antihypertensive therapy, but our findings fail to confirm this hypothesis and suggest that treatment of hypertension may not be the principal reason for the decline in stroke mortality.