Relationship between diastolic blood pressure and the first ischaemic stroke in elderly patients with hypertension

BACKGROUND: It is uncertain how diastolic blood pressure (DBP) may associate with ischaemic stroke in elder patients with hypertension. We aimed to explore this relationship in a Chinese community. METHODS: A total of 3315 participants aged ≥60 years with essential hypertension were enrolled between January 2010 and December 2011, and being followed up until 31 December 2016. DBP levels were categorised into five groups (<60, 60-70, 70-80, 80-90 and ≥90 mm Hg), using 70-80 mm Hg as referent. We performed Cox regression analysis and subgroup analyses to evaluate the relationship between DBP and the incidence of ischaemic stroke. RESULTS: Among the 3315 participants, 44.49% were men and they were 71.4 years old on average. During a median follow-up period of 5.5 years, there were 206 onset cases of ischaemic stroke. The HRs for the first ischaemic stroke in the fully adjusted model were 1.32 (95% CI 0.73 to 2.40) for DBP <70 mm Hg, 1.50 (95% CI 1.13 to 2.73) for DBP between 80 and 89.9 mm Hg and 2.31 (95% CI 1.14 to 4.68) for DBP ≥90 mm Hg compared with DBP between 70 and 79.9 mm Hg (p=0.020 for trend). Subgroup and interaction analysis showed no significant findings. CONCLUSIONS: DBP had a non-linear association with the risk of ischaemic stroke among Chinese elderly patients with hypertension. DBP between 70 and 80 mm Hg may be an appropriate indicator for a lower stroke risk.