Trends in the prevalence of isolated systolic hypertension in the middle-aged population in 1972-1992

We described the trends in the prevalence of isolated systolic hypertension during 1972 to 1992 in five independent population-based cross-sectional random samples in eastern Finland. A total of 15 155 men and 16 126 women aged 30-59 in 1972 and 30-64 years during 1977 to 1992 were included in this study. Standardised methods and measurements of the first screening blood pressure value were used, the size of the cuff bladder changed between 1977 and 1982. We defined isolated systolic hypertension as systolic blood pressure (SBP) greater than or equal to 160 mm Hg and diastolic blood pressure (DBP) <95 mm Hg and diastolic hypertension as nap greater than or equal to 95 mm Hg. The normotensive group comprised subjects whose Sap <160 mm Hg and nap <95 mm Hg. Subjects on antihypertensive medication were classified as having diastolic hypertension. The prevalence of isolated systolic hypertension increased in both sexes and in all age groups except among the youngest women, whereas the prevalence of diastolic hypertension decreased. The proportion of subjects with isolated systolic hypertension out of all hypertensive subjects increased from 11% in 1972 to 24% in 1992 among men and from 15% to 27% among women. The overall decrease in blood pressure, particularly the disproportionate decrease in diastolic over systolic blood in mean pressure may have resulted in the increase in the prevalence of isolated systolic hypertension.