Fletcher et al. BMC Cardiovascular Disorders 2010, 10:37
http://www.biomedcentral.com/1471-2261/10/37
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Background
Stroke is the third largest cause of death in England, and
the single largest cause of adult disability[1]. A National
Audit Office report (2005) highlighted the high cost of
stroke to the NHS: about £2.8 billion per year in direct
care costs, and an additional £1.8 billion per year cost to
the wider economy due to lost productivity and disabil-
ity [2]. Recent estimates suggest that between 30-45% of
strokes are recurrent events, [3] so more effective sec-
ondary prevention could result in significant savings: the
National Audit Office estimates that preventing just 2%
of strokes in England in a year could save care costs of
over £37 million [2]. NICE has identified better control
of hypertension as one of the interventions that are cost
saving for the NHS [4].
The PROGRESS trial demonstrated that blood pres-
sure lowering is beneficial in reducing risk of stroke
amongst both hypertensive and non-hypertensive indivi-
duals with a history of stroke or TIA recruited in sec-
ondary care immediately after their cerebrovascular
event. In this trial, patients were randomised to either a
combination of an ACE inhibitor and thiazide diuretic
against double placebo, or an ACE inhibitor alone
against single placebo. The decision to randomise to
one or two agents was made by the supervising physi-
cian on the basis of whether or not they thought it was
safe to randomise an individual patient to two agents.
Mean blood pressure in the intervention arm was
reduced from 147 mmHg systolic by 9 mmHg (SE 0.3),
and this was associated with a 28% reduction in stroke
risk [5]. The positive result of the PROGRESS trial
raises a supplementary question: by how much should
blood pressure be lowered? No randomised trials have
specifically compared different target blood pressures
(BP) in the post-stroke/TIA population. Observational
data (although not collected specifically in people with a
history of stroke or TIA) suggest that the lower the
blood pressure, the lower the risk of vascular mortality,
at least down to 115 mmHg systolic [6,7]. There is
some evidence from PROGRESS to support this, in that
the sub-group of patients whose baseline BP was
between 120 and 140 mmHg who were randomised to
combination therapy had a significantly reduced risk of
stroke compared with control, though this benefit was
not observed in patients who were randomised to a sin-
gle agent [8]. Guidelines have tended to interpret this
evidence by recommending a target of 130 mmHg for
systolic blood pressure in people with cerebrovascular
disease [9,10]. However, the question remains whether
such a target is prudent in general (42% were rando-
mised to a single agent and gained no benefit) and
whether it is achievable in primary care (PROGRESS
was secondary care based) [5].
Long term management of blood pressure following
stroke and TIA is predominantly carried out in primary
care. Recent studies of blood pressure control in this
setting paint a mixed picture of implementation of
guidelines. In a study of seven general practices in
South Birmingham in 2002, 63% of patients with a pre-
vious stroke or TIA had BP above the 140 mmHg tar-
get, and 80% above the 130 mmHg target [11]. 68% of
these patients were prescribed BP lowering therapy. An
analysis of general practice data on the QRESEARCH
database for 2002-2004 found that of all patients with
incident stroke, blood pressure was not recorded in 25%
of patients, and where it was recorded, it was above the
140 mmHg target in 47% [12]. An analysis of the impact
of the Quality Outcomes Framework (QOF) carried out
for the National Audit Office found that the proportion
of people with a history of stroke or TIA who had their
BP measured in the preceding 15 months rose from
89% to 95% between 2004 and 2005, and the proportion
with a BP below 150 mmHg (the target level for the
QOF) rose from 69% to 80% suggesting some improve-
ment [13]. An analysis of the care of over three thou-
sand patients who had a TIA during 2004-5 found that
60% had a BP equal to or below the 140 mmHg target,
though only 50% were on any blood pressure lowering
therapy [14].
In summary, although there is some evidence that
blood pressure lowering in people who have had a
stroke or TIA is beneficial, there is no clear guidance on
what the target BP should be. Furthermore, data col-
lected from primary care suggest that guidelines from
the British Hypertension Society and Intercollegiate
Stroke Working Party are not being fully implemented.
This research is designed to support implementation of
the guidelines by both addressing the gaps in the under-
lying evidence base, and testing a specific mechanism
for implementation of blood pressure lowering.
Methods/Design
Study aims
The primary aim of Past BP is to determine whether a
more intensive target BP for people with stroke or TIA in
a pragmatic primary care setting will lead to a lower BP.
Secondary aims of the research are to:
• determine the impact of a more intensive BP target
on patient quality of life;
• identify the barriers to implementation of more
intensive blood pressure lowering;
• to explore whether the potential benefits associated
with intensive blood pressure lowering might be out-
weighed by potential adverse effects on quality of life
and costs.