Original Article
Lower systolic blood pressure is associated with poorer survival in long-term survivors of stroke Joosup Kim a, Seana L. Gall b, Mark R. Nelson b, James E. Sharman b, and Amanda G. Thrift a,c See editorial comment on page 746
Background: Lowering blood pressure after stroke reduces the risk of recurrent stroke and other vascular events. However, there is recent evidence that low blood pressure may also result in poor outcome. For the first time, this study aimed to investigate the relationship between blood pressure and outcome in long-term survivors of stroke. Methods: Participants from the North East Melbourne Stroke Incidence Study were contacted at 5 years after stroke for a follow-up assessment. Blood pressure was measured according to a strict protocol. A multivariable Cox proportional hazards regression model was used to assess the association between SBP measurements at 5 years after stroke and outcome (death, acute myocardial infarction or recurrent stroke) to 10 years after stroke. Results: In 5-year survivors of stroke, compared to a SBP of 131–141 mmHg, a SBP of 120 mmHg or less was associated with a 61% greater risk of stroke, acute myocardial infarction and death (hazard ratio 1.61, 95% confidence interval 1.08–2.41, P ¼ 0.019). Compared to the reference category of SBP 131–141 mmHg, there were no differences in outcome in the patients with SBP 121– 130 mmHg (P ¼ 0.491) or 142–210 mmHg (P ¼ 0.313). These findings were not modified when adjusting for prescription of antihypertensive medications. Conclusion: There was a greater risk of poor outcome in long-term survivors of stroke with low SBP. This is further evidence that low SBP may result in poor prognosis. Ideal blood pressure levels for long-term survivors of stroke may need to be reassessed. Keywords: blood pressure, epidemiology, outcome, stroke Abbreviations: IRSD, index of relative socioeconomic disadvantage; NEMESIS, North east Melbourne stroke incidence study; PROFESS, Prevention regimen for effectively avoiding second strokes; PROGRESS, Perindopril protection against recurrent stroke study
INTRODUCTION
L
owering blood pressure after stroke reduces the risk of recurrent stroke and other vascular events, and thus is important in reducing further disability or death after stroke [1,2]. Poststroke care guidelines state that both hypertensive and normotensive survivors of stroke, excluding those with symptomatic hypotension, should be
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prescribed antihypertensive medications and should make lifestyle changes that facilitate lowering of blood pressure [3]. Although results of randomized controlled trials provide evidence that lower blood pressure is better following stroke, some of these findings may be subject to selection bias. For example, in the Perindopril Protection Against Recurrent Stroke Study (PROGRESS), patients with heart failure were excluded from participation [2]. From observational studies and post-hoc analyses of randomized data, there is evidence that lower blood pressure is independently associated with poorer outcomes in patients with coronary artery disease [4], diabetic nephropathy [5], both coronary artery disease and diabetes [6], heart failure [7], and in the elderly [8]. In addition, there is some indirect evidence from a post-hoc analysis of the Ongoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET) [9] that a J-curve exists between SBP and a composite cardiovascular endpoint (cardiovascular mortality, congestive heart failure, myocardial infarction, and stroke). However, there is also evidence from ONTARGET that there is no J-curve for stroke and that lower blood pressure is associated with a reduced risk of stroke. There is similar evidence from randomized data. In the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study [10], there were no differences in the risk of a composite cardiovascular outcome between treatment arms, although there was a reduction in the risk of stroke in patients receiving intensive blood pressurelowering (target SBP
Lower systolic blood pressure is associated with poorer survival in long-term survivors of stroke Joosup Kim a, Seana L. Gall b, Mark R. Nelson b, James E. Sharman b, and Amanda G. Thrift a,c See editorial comment on page 746
Background: Lowering blood pressure after stroke reduces the risk of recurrent stroke and other vascular events. However, there is recent evidence that low blood pressure may also result in poor outcome. For the first time, this study aimed to investigate the relationship between blood pressure and outcome in long-term survivors of stroke. Methods: Participants from the North East Melbourne Stroke Incidence Study were contacted at 5 years after stroke for a follow-up assessment. Blood pressure was measured according to a strict protocol. A multivariable Cox proportional hazards regression model was used to assess the association between SBP measurements at 5 years after stroke and outcome (death, acute myocardial infarction or recurrent stroke) to 10 years after stroke. Results: In 5-year survivors of stroke, compared to a SBP of 131–141 mmHg, a SBP of 120 mmHg or less was associated with a 61% greater risk of stroke, acute myocardial infarction and death (hazard ratio 1.61, 95% confidence interval 1.08–2.41, P ¼ 0.019). Compared to the reference category of SBP 131–141 mmHg, there were no differences in outcome in the patients with SBP 121– 130 mmHg (P ¼ 0.491) or 142–210 mmHg (P ¼ 0.313). These findings were not modified when adjusting for prescription of antihypertensive medications. Conclusion: There was a greater risk of poor outcome in long-term survivors of stroke with low SBP. This is further evidence that low SBP may result in poor prognosis. Ideal blood pressure levels for long-term survivors of stroke may need to be reassessed. Keywords: blood pressure, epidemiology, outcome, stroke Abbreviations: IRSD, index of relative socioeconomic disadvantage; NEMESIS, North east Melbourne stroke incidence study; PROFESS, Prevention regimen for effectively avoiding second strokes; PROGRESS, Perindopril protection against recurrent stroke study
INTRODUCTION
L
owering blood pressure after stroke reduces the risk of recurrent stroke and other vascular events, and thus is important in reducing further disability or death after stroke [1,2]. Poststroke care guidelines state that both hypertensive and normotensive survivors of stroke, excluding those with symptomatic hypotension, should be
904
www.jhypertension.com
prescribed antihypertensive medications and should make lifestyle changes that facilitate lowering of blood pressure [3]. Although results of randomized controlled trials provide evidence that lower blood pressure is better following stroke, some of these findings may be subject to selection bias. For example, in the Perindopril Protection Against Recurrent Stroke Study (PROGRESS), patients with heart failure were excluded from participation [2]. From observational studies and post-hoc analyses of randomized data, there is evidence that lower blood pressure is independently associated with poorer outcomes in patients with coronary artery disease [4], diabetic nephropathy [5], both coronary artery disease and diabetes [6], heart failure [7], and in the elderly [8]. In addition, there is some indirect evidence from a post-hoc analysis of the Ongoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET) [9] that a J-curve exists between SBP and a composite cardiovascular endpoint (cardiovascular mortality, congestive heart failure, myocardial infarction, and stroke). However, there is also evidence from ONTARGET that there is no J-curve for stroke and that lower blood pressure is associated with a reduced risk of stroke. There is similar evidence from randomized data. In the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study [10], there were no differences in the risk of a composite cardiovascular outcome between treatment arms, although there was a reduction in the risk of stroke in patients receiving intensive blood pressurelowering (target SBP
