Download HYPERTENSION (=High Blood Pressure)

HYPERTENSION (High Blood Pressure)
Patient Information Sheet and Practice Policies
Hypertension is not an illness or a disease in itself and most people who have
hypertension will not experience any symptoms from it.
Hypertension is important because it is a risk factor for vascular disease – the higher
your blood pressure the greater your risk of having a heart attack, heart failure, stroke,
vascular dementia and chronic kidney disease. We have treatments that are of proven
value in reducing blood pressure and lowering your risk of these vascular diseases.
BP measurement, diagnosis of hypertension and monitoring
One difficulty we face is that blood pressure when measured in the clinic may be high
due to the stress of being in the clinic – the so-called “white-coat effect” (even though
most doctors don’t wear white coats these days). This means that when we check your
BP in the clinic we can tell you that it is normal or acceptable because a normal BP
can be accepted as such, but we cannot tell you that your BP is high with any degree
of confidence.
To overcome this difficulty we make the diagnosis of hypertension using
Ambulatory Blood Pressure Monitoring (ABPM). This involves having a BP cuff
fitted to your upper arm connected to some electronic equipment that you wear in a
holster. You wear this for 24 hours, during which time it automatically checks your
BP at regular intervals. We then take the average of the daytime readings as the
relevant BP for decision making.
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If your daytime average ABP is <=140/80* it will be regarded as normal.
If your daytime average ABP is >140/80 and you have diabetes, cardiovascular
disease or chronic kidney disease you will be diagnosed with hypertension and
offered treatment for it.
If your daytime average ABP is >140/80 but <150/95 and you do not have
diabetes, cardiovascular disease or chronic kidney disease, you will be offered a
cardiovascular disease risk assessment. This is a measure of the likelihood of you
having a heart attack or stroke in the next 10 years. It takes into account your age,
sex, body mass index, smoking, cholesterol and family history as well as your BP.
If you have a risk >20% you will be diagnosed with hypertension and offered
treatment for the lowering of both your BP and your cholesterol.
If your daytime average ABP is >=150/95 you will be diagnosed with
hypertension and offered treatment for it. You will also be offered a
cardiovascular disease risk assessment to consider the need for cholesterollowering.
For all of these BP measures both the systolic and diastolic BP should be below the
stated levels (a day average ABP of 141/80 is not normal).
If you smoke you are advised to stop irrespective of any other consideration.
Once you are on treatment for hypertension we need a reliable method of monitoring
your BP. Our favoured method, which we recommend to all people who are treated
for hypertension, is regular home BP monitoring. Home BP monitors are available
from most pharmacies and are available on-line. You will pay between £20 and £60
depending on which model you get. In general the more expensive models are more
accurate, more reliable, easier to use and last longer. All these monitors are assessed
by the British Hypertension Society for accuracy. The two makes which consistently
have the best performance are OMRON and AND – we recommend that you get a
model made by one of these two companies. BP monitors are available with upper
arm, wrist or finger cuffs – only models with upper arm cuffs are recommended.
Obese people with very large upper arms will need an outsize cuff. This generally
requires a special model of home BP machine which will be more expensive - £100 to
£120.
When you first get your BP machine read the instructions and ensure that you are
happy using it. If in doubt book an appointment with one of our Healthcare Assistants
and she will check your technique. Ignore the first few BP readings until you are
confident and comfortable with your use of the machine. After that the frequency of
BP checking is largely up to you and there is no need to be obsessive about it. Our
usual practice will be to take the average of your most recent 10 readings – and for
routine monitoring it doesn’t really matter whether you did them all the day before the
appointment or at monthly intervals for 10 months. You should vary the time of day
and the day of the week you do your BP measurements rather than doing them
according to a set daily or weekly routine.
Whenever you check your BP you should sit and rest for 10 minutes before using the
machine. You should measure your BP twice with a 5 minute interval between
measurements. You should then record the lower of the two readings in a notebook
together with the date of measurement. Bring your notebook to your clinic
appointments.
Ideal BP is around 120/70. For many people with hypertension it is not possible to
achieve ideal BP. The Quality and Outcomes Framework (QOF), which assesses
quality in general practice, uses targets of 150/90 if you do not have diabetes and
140/80 if you do. If you are on treatment and your most recent relevant BP* is within
the QOF target range we will generally be satisfied that your current treatment is
adequate.
*There are two elements of the QOF target which are frankly stupid. Firstly, it states that the most
recent BP should be within 9 months of the 31st March – which means that for well-controlled people
on an annual review we are penalised if that review occurs between 1 st April and 30th June. Secondly, it
states that it is the most recent BP that should be in target – taken to its illogical limits this may mean
the last reading of a 24-hour BP monitor test or the last of your home readings. To introduce a little
common sense, we use and record the most recent relevant BP – this may be the average of a recent
ABP test, the average of recent home readings or a clinic reading if in-target. In any case it is the most
recent BP value upon which a decision regarding the adequacy of current treatment is based.
If you are on treatment and your most recent relevant BP is higher than the QOF
target range we (you and us in partnership) can make one of the following choices:
 Increase the dosage of your current medication
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Add an additional medication
Substitute a new medication for one of your existing medications (if the
prescription of your anti-hypertensive medications follows the
recommendations outlined below, this will not usually be the right choice)
Accept the current BP and an increased risk of vascular disease either because
you are already on the maximum tolerated treatment or because you do not
wish to increase or change your treatment despite medical advice to do so.
We will then record an exception from the QOF hypertension indicators.
Treatment of hypertension
Broadly there are 5 classes of anti-hypertensive agent:
1. Angiotensin-converting Enzyme Inhibitors (ACE inhibitors) such as
Perindopril and other drugs ending in –pril; and Angiotensin-II Receptor
Blockers (ARB’s) such as Irbesartan and other drugs ending in –sartan.
2. Calcium-channel Blockers such as Amlodipine and other drugs ending in –
ipine.
3. Diuretics. Traditionally we would use Bendrofluamethiazide but increasingly
Chlortalidone or Indapamide are preferred. Other diuretics occasionally used
in hypertension are Furosemide and Spironolactone.
4. Beta-blockers such as bisoprolol and other drugs ending in –olol.
5. Others – most commonly used are alpha-blockers, but there is a range of little
used, mostly antiquated and poorly tolerated products.
About 50% of people treated for hypertension will be adequately controlled on one
medication and 50% will require two or more anti-hypertensive medications.
STEP 1.
The ACE-inhibitors and Calcium-channel blockers have the best evidence for
preventing heart attacks and strokes and are therefore our first choice medications.
ACE-inhibitors are first choice in people aged <55 and in people with diabetes.*
They are generally well-tolerated. They cause a small lowering of blood glucose and
reduce the likelihood of developing diabetes. Important unwanted effects include:
 A persistent irritating cough which is genetically determined and affects about
10% of people. If you develop this cough it will be relieved within 1 month of
stopping treatment.
 A rise in blood potassium occurs occasionally and is more frequent in the
elderly. We will do a blood test to check this soon after starting treatment or
after any increase in dosage and then every year or so.
 Contraindicated in pregnancy and so may be unsuitable for women with childbearing potential.
ACE-inhibitors also produce a rise in serum creatinine which is usually a marker of a decline in kidney
function (a dramatic rise is a marker of renal artery stenosis), but they are generally regarded by renal
physicians as good for kidneys and there is some evidence for this.
* This recommendation for diabetes is evidence-based but has still not reached the NICE guidance.
Calcium-channel blockers are first choice in people aged 55+ and in black people of
African or Caribbean descent. They are generally well-tolerated. The most frequent
unwanted effect is ankle swelling.
Angiotensin-receptor Blockers are used in place of ACE-inhibitors where ACEinhibitors are not tolerated. They have less evidence of effectiveness in preventing
heart attacks and strokes and are 10x more expensive, but they do lower BP and do
not produce the irritating cough.
Diuretics Chlortalidone is preferred where a diuretic effect is desired and the risk of
diabetes is low. Indapamide is preferred where a diuretic effect is undesirable and/or
the patient has diabetes or a high risk of developing diabetes.*
Diuretics may be used in place of calcium-channel blockers where calcium-channel
blockers are not tolerated or as an additional treatment especially where calciumchannel blockers are causing ankle swelling.
* Indapamide causes less blood glucose rise than chlortalidone and although it is classed as a “thiazidelike diuretic” it is neither like a thiazide nor does it have a diuretic effect.
Beta-blockers are third choice treatments in younger people who are intolerant of
both ACE inhibitors and ARBs. However, they may be considered as first choice in
women of child-bearing potential (beta-blockers are first choice for management of
hypertension in pregnancy) and in people with a significant anxiety state or chronic
headache. The traditional combination of a beta-blocker and a thiazide diuretic is now
known to increase the risk of diabetes and so is to be avoided where possible.
STEP 2
ACE-inhibitor (or ARB if ACE-inhibitor not tolerated) +
Calcium-channel blocker (or diuretic if CCB not tolerated)
STEP 3
ACE-inhibitor (or ARB if ACE-inhibitor not tolerated) + Calcium-channel blocker +
Diuretic
STEP 4 options:
 Add Spironolactone (if K <4.5 and eGFR >60, check U&E within 1 month)
 Add an alpha-blocker
 Add a beta-blocker
Prevention and Numbers Needed to Treat (NNT)
You may be reassured to see a reduced BP, but we treat hypertension in order to
prevent cardiovascular events. As an individual you can never really know that a
preventative medication is helping you because nothing happens. You cannot know
that you were going to have a heart attack or a stroke and you cannot know that you
have had a heart attack or stroke prevented by the medication you are taking. Even if
you do have a cardiovascular event you cannot know whether or not it was delayed by
treatment.
However, we do know from clinical trials on large populations that if we treat enough
people we will prevent some of them from having heart attacks and strokes.
For example:
In 100 people on treatment for 5 years 10 have a cardiovascular event and
In 100 people on a placebo (inactive) for 5 years 20 have a cardiovascular event.
We can say that the treatment has prevented 10 events in 100 people
But we can’t say which 10 people have benefitted.
80 people could not benefit because they were not destined to have an event and
10 people who were destined to have an event have still had an event despite being on
treatment.
In this example we need to treat 10 people for 5 years for 1 person to benefit:
NNT=10.
The higher risk the population, the greater the expected number of events and the
smaller the NNT to prevent an event. So if you have already had an event (heart
attack or stroke) your risk is high and the NNT is ~ 10.
If you have type II diabetes your risk is fairly high and the NNT is ~ 20.
If you have not had an event and do not have diabetes (primary prevention) costeffectiveness models suggest that if your 10 year cardiovascular event risk is 20% or
higher it is worthwhile to treat you – at the 20% risk level the NNT is between 50 and
150. This comes down to NNT ~30 if you take a statin to lower your cholesterol as
well as the BP lowering medication.
Your risk rises and the NNT falls with age – the older you are the more likely you are
to benefit from treatment in the next 5 years. Clinical trials are not usually extended
beyond 5 years so we don’t know if 10 years of treatment starting at age 60 will
prevent more events than 5 years of treatment starting at age 65, but there are strong
theoretical grounds for thinking that it would.
The higher your BP the lower the NNT.
We have around 1000 people with hypertension in the practice. If we treat all of them
with BP lowering medication and a statin for 5 years we will prevent 30 to 35
cardiovascular events.
We have around 400 people with type II diabetes and hypertension. If we treat all of
them for 5 years we will prevent 20 cardiovascular events.
Dr CPM Lewis
01/08/2011