Lifetime risk of stroke and impact of hypertension: estimates from the adult health study in Hiroshima and Nagasaki

Abstract

Very few reports have been published on lifetime risk (LTR) of stroke by blood pressure (BP) group. This study included participants in the Radiation Effects Research Foundation Adult Health Study who have been followed up by biennial health examinations since 1958. We calculated the LTR of stroke for various BP-based groups among 7847 subjects who had not been diagnosed with stroke before the index age of 55 years using cumulative incidence analysis adjusting for competing risks. By 2003, 868 subjects had suffered stroke (512 (58.9%) were women and 542 (62.4%) experienced ischemic stroke). BP was a significant factor in determining risk of stroke for men and women, with distributions of cumulative risk for stroke significantly different across BP groups. The LTR of all-stroke for normotension (systolic BP/diastolic BP o120/80 mm Hg), prehypertension (120-139/80-89 mm Hg), stage1 hypertension (140-159/90-99 mm Hg) and stage 2 hypertension (4160/100 mm Hg) were 13.8-16.9-25.8-25.8% in men and 16.0-19.9-24.0-30.5% in women, respectively (Po0.001 among BP groups in both sexes). The estimates did not differ significantly (P¼0.16) between normotensive and prehypertensive subjects. One in five Japanese atomic bomb survivor subjects experienced stroke over their lifetime from the age of 55 years. Long-term stroke risks were elevated in those with hypertension (4140/90 mm Hg) at any of the index ages of 45, 55, 65 and 75 years.

Hypertension and lifetime risk of stroke

“…These were observed across all the studied index ages as well as on both sexes. Our estimates of LTR of stroke in the Suita study are also consistent with the reported LTR of stroke from the Netherlands [19], United States [20], United Kingdom [21], as well as another study from Japan [22]. The LTRs of stroke for middle-aged men and women were substantial.…”

“…Also, it was observed that individuals who maintained or decreased their BP to normal levels had the lowest remaining LTR for stroke, compared with individuals who had or developed hypertension by 55 years of age [27]. Authors from Japan, studying the Radiation Effects Research Foundation Adult Health Study cohort, showed that the LTR of stroke and its subtypes differed across the categories in BP among men and women of index age of 55 years [22]. The LTR of stroke for normotensive men and women was 13.8 and 16.0%, respectively, whereas the LTR of stroke for stage 2 hypertensive men and women were 25.8 and 30.5%, respectively [22].…”

“…The LTRs of stroke for middle-aged men and women were substantial. The observed probabilities from the Rotterdam [19], Framingham [20], Radiation Effects Research Foundation Adult Health [22], and Cardiovascular research using linked bespoke studies and electronic health records [21] studies illustrate that approximately one in five men and women of middle age will experience stroke in their remaining lifetime.…”

“…Although there are a number of reports regarding the LTR of cardiovascular diseases, including stroke [16,17,[23][24][25][26], only a few prior reports have presented the effect of hypertension on the LTR of stroke [20][21][22]27]. A recent publication from the UK, based on an analysis on electronic records of 1.25 million people during 1997 to 2010, reported that people aged 30 years or older with hypertension have a LTR for strokes compared with those with normal BP [21].…”

Recognizing the risk of cardiovascular diseases: quantifying the short-term and lifetime risk projections

“…[15][16][17] However, these studies did not investigate the effect of blood pressure, by category, on the lifetime risk of these diseases. In this issue of the journal, Takahashi et al 18 present the lifetime risk estimates of stroke according to different levels of blood pressure for middle-aged men and women. The authors analyzed the data relating to the participants enrolled in the Radiation Effects Research Foundation Adult Health Study, who have been longitudinally followed since 1958.…”