COMMENTARY

ESC: Guideline Changes Expected After Blood Pressure Study

Prof Kazem Rahimi

Disclosures

August 31, 2020

Professor Kazem Rahimi, University of Oxford, on the findings of the Blood Pressure Lowering Treatment Trialists’ Collaboration (BPLTTC) trial he presented to the 2020 European Society for Cardiology virtual meeting.

This transcript has been edited for clarity.

What were your headline findings?

The headline finding was that blood pressure reduction works equally, irrespective of presence or absence of cardiovascular disease, and irrespective of the baseline pressure value itself, down to a level of systolic blood pressure of 120 mm mercury or less.

How did you reach the conclusions?

In order to get to that result, we had to gather an enormous amount of data to be able to look at differences between subgroups of individuals. And this work is really the combination of data collection and processing activity, which started in 2014 with collaboration of major clinical trialists across the world. There are about 50 randomised clinical trials, large scale, randomised clinical trials, that the investigators shared the data with us, that is the full data set. And we essentially put all that data together in a single data set. And we were able to perform those stratified analyses that we are presenting here at this meeting.

And in this particular study, obviously, we're interested to look at whether treatment effects differed in people with prior cardiovascular disease, and whether the blood pressure itself, the systolic blood pressure, modified the proportion of risk reductions observed among those individuals who have been treated.

The database itself currently includes about 350,000 randomised individuals, which makes it the largest source of randomised trials ever, to my knowledge.

Will practice now have to change?

I very much hope so, because if you look at what has been happening globally, the interpretation of the current evidence has been quite diverging. In some parts of the world, such as the US, there has been generalisation of the evidence indicating that probably we should not differentiate between people who have had previous cardiovascular disease, or [those who] didn't. In other parts of the world, for instance, in Europe and the UK, there has been a clear distinction between those people. And pretty much irrespective of where you look, the perception among physicians and those who have put those guidelines together, those experts, has been that if you want to consider treatments with blood pressure-lowering medications, the starting point should be to look at individuals' [initial] blood pressure.

This study fundamentally challenges that way of thinking and suggests that blood pressure itself, or presence of absence of cardiovascular disease, should not be a reason for withholding treatment among those individuals. We believe that this will have far reaching implications on clinical practice.

What will the National Institute for Health and Care Excellence (NICE) have to do differently for example?

NICE currently has two different guidelines, one for hypertension treatment, that is people who have not experienced cardiovascular disease before, and one that looks at cardiovascular risk management in people with prior cardiovascular disease.

One question that this study brings up is when it's appropriate to have different guidelines for cardiovascular risk management, using the same medications? So that is one question.

The second aspect is if you look at the hypertension guidelines currently, in people without previous cardiovascular disease, NICE is very clear that the starting point of assessment should be an individual's systolic blood pressure being greater than 140.

In other words, if your blood pressure is 139, you should not be considered for treatment even if your cardiovascular disease risk is high.

I think this study would challenge that. And, you know, to be fair, I mean, NICE, did a rigorous assessment of the prior evidence, and they found that in that particular category of individuals, when the blood pressure is less than 140, there is little conclusive evidence. And this study should precisely fill that gap. We're having substantial numbers of individuals, really thousands of people and thousands of events, in fact, in the category of people with normal or high normal blood pressure, for them to be able to reassess the situation.

Were you surprised by the findings?

We have previously carried out studies that have shown evidence against, in a sense, the modification of treatment by baseline blood pressure or disease.

But what we have acknowledged, and what NICE has also noticed, was that the evidence really in the lower blood pressure categories was limited. And yes, what we were surprised about was that when we pulled that data together at the level of individuals, how much information is actually available currently, and how many people have a normal or high normal blood pressure only, we're randomising those major clinical trials.

So this is substantial. I mean, if you compare it, for instance, with one of the biggest meta-analyses using tabular data that we have used, that we have published in The Lancet in 2015, that had very few numbers of people or very few trials that fell into that category. Here we've got at least six times as many events in those categories of individuals. So that is surprising: the amount of information.

The message to be honest, this is something that we have been expecting, but you know, the nature of science is we never know. So we pre-specify that protocol. We knew there is, you know, there's good reason why professionals across the world have been in disagreement about what should be done in that category. 

If you look at it, physiologically, we believed that a distinction should not be made, but we didn't know what the findings would look like.

And it is a surprising and to some extent, confirming to just see that, that doesn't make any difference.

How are you finding the virtual conference as compared with networking face-to-face?

It has pros and cons. I mean, what is missing is really the social interaction with people and pre-recorded presentations, the immediate feedback that one gets to be able to just respond - that gets lost. But on the other hand the flexibility to access the information and also you know, making the conference accessible to a much wider audience. I mean, over 100,000 people registered, that is unprecedented, and I think for science, it is good, if more people are able to access that, that information.

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