OET Listening ส่วนที่ C: SPRINT Blood Pressure Trial Overview

Hello, I'm Dr Pamela Skelton, Consultant Cardiologist at this hospital,

and I'm talking about the recent SPRINT study into the effects of setting lower blood-pressure targets,

which in turn affects the advice and medication which patients are given.

I'm going to describe the patients who were selected,

how the trial was conducted

and the implications of its results for us all as health professionals.

First, the trial itself.

It involved over 9000 hypertensive participants, aged 50-plus,

most of whom were on blood-pressure medication.

They were randomly assigned to one of two groups,

one with a goal of less than 120 millimetres systolic BP,

the other with a goal of less than 140 millimetres, the traditional standard.

The intention was to follow these patients for 5 years,

factoring in the usual drop-out rate.

As it turned out, however, the trial was stopped after just 3 years

thanks to an all cause mortality reduction of nearly 30% for the 120-group,

which was definitive and shocking but wonderful.

As I mentioned, the participants were over-fifties

and it goes without saying that as people age, they develop more diseases and health problems as a matter of course.

But there was a specific group of over-seventy-fives who did just as well as younger patients.

Before the trial, some medics referred to the natural stiffening of the arteries with ageing,

suggesting that a hundred-and-twenty was too low a target for the over-seventy-fives,

risking an increase of dizzy spells which would affect general wellbeing.

But this concern turned out to be unfounded.

Others thought there'd be a failure to take the number of tablets needed to reach a BP of 120,

especially among older participants.

Again, this wasn't an issue.

The average needed was just three per day.

The over-seventy-fives, already on various drugs, didn't object to extra medication.

Participants from this age group who didn't finish the trial were taken out because some conditions, which were already present, worsened;

for example in some cases obesity levels rose too high.

To manage their blood pressure, participants were given standard drugs,

nothing experimental, just drugs that are readily available and low-cost.

Another key factor was that blood pressure was measured in a very specific way.

Rather than give patients an arm cuff for at-home 24-hour ambulatory monitoring,

an automated machine was used at the hospital.

This took three separate readings and averaged them.

Also, readings were taken while staff were out of the room

to avoid what's called 'white coat syndrome' in patients.

Now, some of you may be familiar with the ACCORD study into blood pressure levels several years ago,

which in some respects was similar to SPRINT.

There are some differences, though.

For example, ACCORD was about half the size of SPRINT,

and unlike SPRINT, the ACCORD study allowed diabetic patients to take part.

Despite this, in general, the ACCORD participants were rather lower risk than those in the SPRINT trial.

Probably because of the slightly lower average age.

The ACCORD trial didn't show a statistically significant benefit for overall cardiovascular outcomes,

but there was a clear forty percent reduction in strokes,

even though that was a secondary outcome.

So, to summarise, the SPRINT trial seems to support 120 as a recommended blood pressure target.

This is doubtless a landmark study

and, importantly, one which was sponsored by government

rather than by the interests of the pharmaceutical corporations.

I recommend a note of caution though,

as SPRINT does contradict previous findings.

The Cochrane View in 2011, for example,

said that lowering to under 140 didn't produce a change in the risk of death overall.

However, we must bear in mind that Cochrane was looking retrospectively at trials which weren't actually focused on the same particular issue.

So it's worth doing a full and systematic evaluation,

to see where the SPRINT trial fits in with what we already know.

It's interesting that a few GPs have already been working with older patients to hit lower blood-pressure goals,

and the new data will doubtless encourage greater take-up of this more interventionist line of attack.

But the SPRINT results don't mean that everyone with hypertension should be dropping to under a hundred and twenty.

Plus, to achieve those lower levels,

it's unlikely that lifestyle changes alone would be enough,

it could well require several anti-hypertensive drugs as well.

There remain some unanswered questions, of course.

For example, whether other groups, like those with a lower heart-attack risk, need to keep their blood pressure that low.

So, while SPRINT can help guide doctors' decisions about some patients,

it doesn't mean that a new universal standard for blood pressure is in order.

Instead, it's a good reason for everyone to discuss with their doctor, their own ideal and particular target.