Isolated systolic hypertension as a major risk factor for stroke and myocardial infarction and an unexploited source of cardiovascular prevention: a prospective population-based study.

The purpose of this study was to determine the prevalence of isolated systolic hypertension (ISH) and associated risk of major cardiovascular events. The Copenhagen City Heart Study is a prospective population survey with cardiovascular examinations at 5-year intervals. Blood pressure measurement was carried out as office blood pressure. ISH was defined as SBP > or = 160 mmHg and DBP < 90 mm Hg. The risk of stroke and myocardial infarction (MI) in association with ISH was assessed using a multivariate Cox regression model. Follow-up was carried out by means of the National Patients Register and Death Register. The 19,698 subjects were randomly selected after age stratification from an area of central Copenhagen. Subjects (n = 6621) were included if > or = 50 years, not on anti-hypertensive or cardiac medicine, and had no history of a previous stroke or MI. Initial cases of verified stroke or MI were recorded from 1976 to 1988. The prevalence of ISH showed an age-related increase from 3% in the 55-year olds to 13% in the 72-year olds. No sex difference was found. Relative risk of stroke corrected for other risk factors was 3.0 (95% CI 1.6-5.3) for women and 2.7 (1.8-4.3) for men. This was the highest relative risk among all hypertensive groups. Relative risk of MI corrected for other risk factors was 0.8 (0.3-2.0) for women and 1.6 (1.0-2.5) for men. Population attributable risk for stroke associated with ISH is up to 30%.(ABSTRACT TRUNCATED AT 250 WORDS)