Isolated systolic hypertension and 29-year cardiovascular mortality risk in Japanese adults aged 30--49 years.

Objective: The prognostic implication of isolated systolic hypertension (ISH), defined as SBP at least 140 mmHg and DBP less than 90 mmHg, among young-to-middle-aged adults remains controversial. We examined the association of ISH with cardiovascular disease (CVD) risk in adults aged 30-49 years.

Methods: In a prospective cohort of representative Japanese general populations from the NIPPON DATA80 (1980-2009), we studied 4776 participants (mean age, 39.4 years; 55.4% women) without clinical CVD or antihypertensive medication. Participants were classified as follows: normal blood pressure (BP) (SBP/DBP, <120/<80 mmHg), high-normal BP (120-129/<80 mmHg), elevated BP (130-139/80-89 mmHg), ISH, isolated diastolic hypertension (IDH) (<140/≥90 mmHg), and systolic--diastolic hypertension (SDH) (≥140/≥90 mmHg).

Results: ISH was observed in 389 (8.1%) participants. During the 29-year follow-up, 115 participants died of CVD, 28 of coronary heart disease, and 49 of stroke. Cox proportional hazards models adjusted for demographics and CVD risk factors showed that participants with ISH had higher risk of CVD mortality than those with normal BP [hazard ratio (confidence interval), 4.10 (1.87-9.03)]. The magnitude of CVD mortality risk related to ISH was comparable with that related to IDH [3.38 (1.31-8.72)] and not as great as that related to SDH [5.41 (2.63-11.14)]. We found significant associations of ISH with coronary and stroke mortality. The association of ISH with CVD mortality was consistent across men and women and those aged 30-39 and 40-49 years.

Conclusion: ISH among young-to-middle-aged Japanese adults was independently associated with higher risk of CVD mortality later in life.