BP target for stroke prevention in Asians
For stroke prevention in an Asian population, a blood pressure (BP) of <140/90 mm Hg is a reasonable target and particularly, 120-130/80 mm Hg may be optimal, according to a presentation at the APCH 2017 Meeting in Singapore.
“BP targets for stroke prevention are based largely on trials performed in non-Asian populations,” although the highest global stroke mortality rate occurs in Asia (particularly in Mongolia, Russia, China, and Southeast Asia) and that the risk of stroke was higher in hypertensive Asians than Caucasians, noted Dr Narayanaswamy Ramani from Raffles Hospital, Singapore. [Hypertension 2007;50:991-997]
“Hypertension is a strong risk factor for stroke, more-so among Asians … In addition, advance age compounds the risk ─ older persons with higher BP have [an even] higher risk of stroke,” said Ramani. As hypertension is the most modifiable risk factor for stroke, BP lowering is important for stroke prevention.
However, there is no clear answer as to what should be the ideal BP target for preventing stroke in Asians, according to Ramani.
Based on the COPE* study in Japan, individuals with a BP of <140/90 mm Hg had a reduced risk of stroke than those with a BP of >140/90 mm Hg. [J Hypertens 2011;29:1649-1659; Hypertens Res 2013;36:1088-1095] This finding is supported by the FEVER** study involving 9,800 Chinese, which shows reductions in the risk of both fatal and nonfatal stroke by 27 percent (p=0.001), all cardiovascular events by 35 percent (p=0.012), and cardiovascular death by 33 percent (p=0.019) in subjects who achieved an average BP of 137.3/82.5 mm Hg vs 142.5/85 mm Hg. [J Hypertens 2005;23:2157-2172]
These data suggest that a BP target of <140/90 mm Hg is reasonable, and probably even a BP of <140/80 mm Hg, for stroke prevention in Asians, said Ramani.
Nonetheless, some studies have demonstrated conflicting results, with the JATOS trial in Japan showing that achieving a systolic BP of <140 mm Hg is no better than 140–160 mm Hg, while the VALISH study in Japan suggests no difference in stroke risk between those with <130, 130–145, and >145 mm Hg SBP. [Hypertens Res 2008;31:2115-2127; Hypertension 2017;69:220-227]
Notwithstanding the contradictory findings from JATOS and VALISH, the CSPPT*** study on 17,280 Chinese suggests a J-curve relationship between SBP and stroke risk: Compared with participants who achieved an on-treatment SBP of 120–130 mm Hg, the risk of first stroke was increased with SBP of 130–135 mm Hg (HR, 1.63), 135–140 mm Hg (HR, 1.85) and particularly, <120 mm Hg (HR, 4.37). [Hypertension 2017;69:697-704]
In general, there are limited randomized clinical trials on Asians, with most of the trials done in China or Japan, observed Ramani. However, Asians consist of many different populations besides Chinese and Japanese, and hence, more trials are needed in other Asian populations, he continued.
“The CSPPT trial suggests that a BP target of 120–130/80 mm Hg may be optimal in Asians … but more studies are needed,” he said, suggesting a BP target of <130/80 mm Hg for preventing stroke in Asians who have had a stroke or transient ischaemia.