Subtype hypertension and risk of stroke in middle-aged and older Chinese: a 10-year follow-up study.

BACKGROUND AND PURPOSE

Hypertension is the most important indicator of stroke. We aim to compare the long-term effects of the subtypes of hypertension on the risk of stroke in a Chinese cohort.

METHODS

A total of 26,587 subjects > or =35 years of age and free of stroke were recruited in 5 cities in 1987. The subtypes of hypertension were defined as isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), systolic and diastolic hypertension (SDH), as well as managed hypertension (MHT), according to the criteria of systolic blood pressure > or =140 or diastolic blood pressure >90 mm Hg or under antihypertensive treatment. The relative risks of stroke with the subtypes of hypertension, compared with normotensives, were estimated using the Cox model after adjustments for age, sex, and other confounders.

RESULTS

The prevalence of hypertension was: ISH 7.1%, SDH 18.4%, IDH 6.7%, and MHT 3.9%. During a total of 233 437 person years of follow-up, 1107 subjects developed stroke (614 ischemic and 451 hemorrhagic events and 42 unclassified). SDH patients were at the highest risk of stroke among all the hypertensives. The hazard ratio and 95% CI was 2.96 (2.49 to 3.52) for all stroke, 4.05 (3.10 to 5.30) for hemorrhagic, and 2.33 (1.84 to 2.95) for ischemic stroke. Although the incidence of stroke was higher in the older population, the effect of hypertension, especially SDH, on hemorrhagic stroke is stronger in the middle-aged population.

CONCLUSIONS

ISH and IDH are similarly prevalent in the population; both are independent predictors of stroke. Patients with SDH are at the highest risk of stroke and should be treated more aggressively.