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INSIDE HEALTH

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Programme 1. - Flibanserin; Strokes in young people; Outdoor swimming; Research terminology - Causation v Association

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TX:听 09.06.15听 2100-2130

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PRESENTER:听 MARK PORTER

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PRODUCER:听 ERIKA WRIGHT

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Porter

Hello and welcome back to a new series of Inside Health. Coming up today:

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Pink Viagra - really? We reveal the truth behind the headlines promising help for women troubled by low sex drive.

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Young strokes - we examine claims that the rate in people in their 40s and 50s has increased, bucking the general downward trend in the UK.

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And talking of trends we look at the pros and cons of open water swimming which is enjoying a huge resurgence at the moment. When I say we鈥�..

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Clip

Okay, so this is just the wooden steps, I鈥檓 just lowering myself centimetre by frozen centimetre.听 It鈥檚 quite cold.听 [Laughter]

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Porter

More from a shivering Margaret McCartney later.

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But first we were intrigued by recent headlines about the possible launch of a new treatment - flibanserin - for low sex drive in women. Or as the 大象传媒 online news put it:

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Female Viagra nears US approval after expert backing.

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Porter

With one patient who had taken the new medication quoted as saying:

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I want to want my husband, it is that simple. 听For us flibanserin is a relationship saving and life changing drug.

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Porter

Well to provide some perspective on this apparent breakthrough I am joined on the line by Dr Cynthia Graham from the Centre for Sexual Health Research at the University of Southampton, and a research fellow at The Kinsey Institute in America.

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Graham

There鈥檚 been a lot in the media and in social media suggesting it has been approved but this was the vote taken by an expert advisory panel for the FDA 鈥� the Food and Drug Administration 鈥� in the States and the vote was in favour but with some real concerns and precautions that they recommended.听 Nobody voted for approval without any extra precautions.

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Porter

So it鈥檚 still got some hurdles to go through?

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Graham

It does.听 August will be the time that the FDA make a final decision.

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Porter

How does it actually work?

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Graham

Well that鈥檚 a great question because much of the media labels this drug as Viagra for women, as you said, or pink Viagra and in fact it works very differently than Viagra.听 Viagra is first of all targeted at men with erectile problems, it works by increasing blood flow to the genitals.听 This drug -听 Flibanserin 鈥� very different.听 First of all it鈥檚 targeted at women with sexual desire problems, rather than arousal problems, or any kind of vaginal kind of dryness, anything like that and it acts centrally on the brain.听 So what it does is sort of change the balance of neurotransmitters in the brain, so it鈥檚 quite a different drug than Viagra.

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Porter

How effective have the early trials shown this drug to be, I mean does it work?

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Graham

Well that鈥檚 one of the key questions.听 It鈥檚 twice been rejected by the FDA, I should stress, so this is the third attempt to try and have the drug approved.听 And the early concerns were about efficacy.听 The way that this is measured is usually in terms of what are called satisfying sexual events or SSEs and those have been shown to increase by just under one per month for a woman.听 The other thing is there鈥檚 a very large placebo response, with this drug, with most drugs actually for sexual problems, but it鈥檚 estimated that one in 10 women taking the medication may actually note any improvement.

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Porter

So it鈥檚 not brilliantly effective but what about the downside, what sort of side effects does it have?

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Graham

So that鈥檚 my concern really is that you鈥檙e looking at a drug with minimal benefit, likely, but also there are some real concerns.听 In fact the concerns have heightened in the last week.听 So before this panel the drug company, Sprout, which is the one trying for approval, released a report and the concerns are really about the side effects now as well as the minimal benefit but I think the focus is on the side effects.听 Things like drop in blood pressure, sleepiness, fainting spells, dizziness.听 And the most worrying thing of all is the potential interaction with other drugs.听 And the one that鈥檚 been focused on is alcohol, so it seems that alcohol may actually interact with the drug and make the side effects worse.听 But the drug company only studied two women in a trial of 25, so 23 of the participants in the trial on alcohol interactions were men.

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Porter

The other controversial thing about this drug is who you鈥檙e going to give it to 鈥� how have they worked out who this is supposed to help?

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Graham

Well the focus for this drug is on premenopausal women who have no medical causes for low desire and that have kind of clinically significant low desire, so they鈥檙e meant to be distressed by it.听 They鈥檙e talking about use with a population that have quite marked and persistent low desire.听 The problem is that once it鈥檚 approved it鈥檚 unlikely to be used only in those situations and we know that has happened of course with a lot of drugs.听 My concern is there鈥檚 so much hype about this drug really as something that鈥檚 going to change the lives of many women.听 And low sexual desire is a significant problem and it is the most common sexual problem that women report, so I鈥檓 not denying the fact that there鈥檚 an issue here.听 But I don鈥檛 think that this drug has actually been proven safe and effective.

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Porter

So we have a problem potentially but you鈥檙e not convinced that this is the answer to it?

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Graham

Exactly.听 I鈥檓 someone who鈥檚 not against the idea of medications being developed and evaluated for use with women鈥檚 sexual problems.听 I think that some women will respond well.听 Some women may even respond to this drug, I think it would be a small group but I think the concerns outweigh the benefits at this stage, particularly the side effects.

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Porter

Dr Cynthia Graham thank you very much.

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To be clear even if the drug is approved in the States it still won鈥檛 be available here, not without clearing further regulatory hurdles.听 听And we will be returning to the increasing medicalisation of female sexual health later in the series.

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Strokes were also making the headlines while we were off air following research by the Stroke Association suggesting rates had soared in younger men and women over the last 14 years.听 While strokes are becoming less common in older people, analysis of hospital admission data in England showed a 46% increase in men aged between 40 and 54 and a 30% rise in the women of the same age.

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Well to debate what might be going on Peter Rothwell, Professor of Clinical Neurology at the University of Oxford; Rustam Al-Shahi Salman, who is Professor of Clinical Neurology at the University of Edinburgh and Inside Health鈥檚 resident sceptic Dr Margaret McCartney.听

Margaret were you surprised that there appears to be such a dramatic rise in strokes among people of working age?

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McCartney

Well I was pretty taken aback by these figures because all the data that I鈥檝e been looking at up till now has been fairly consistent in telling us that stroke rates in the UK overall have been falling over the last decade or so.听 So I was particularly intrigued to look at this data and to me this is a really good example of a data dump, so it鈥檚 quite easy to go and ask for some data, some raw data, but the problem is that that data鈥檚 really not of very high quality because you鈥檙e looking for quite small changes overall in stroke rates to know whether or not that鈥檚 actually a rise or a fall.

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Porter

Peter, in Oxford, if I can come to you.听 What was your initial reaction to this?

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Rothwell

One of the problems I think is the fact that it鈥檚 based on hospital admission data, so it鈥檚 measuring the number of admissions that are coded as being due to stroke, which is quite different to the number of strokes actually happening.

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Porter

And why might there be a discrepancy between those two, one would presume that people wouldn鈥檛 be coded as having a stroke unless they鈥檇 actually had one?

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Rothwell

You鈥檇 be surprised, hospital coding isn鈥檛 as good as you might hope it was.听 And it also changes over time.听 For example stroke incidents in Japan changed 10 fold over a couple of years in the 1990s when they changed the coding of a sudden death from stroke to heart attack.听 So there are all sorts of artefacts that can get in the way of interpreting those sort of data.

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Porter

Rustam, your take when you saw this, I mean does it reflect what鈥檚 actually happening do you think, are we seeing stroke rates rising in younger people do you think?

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Salman

Well certainly in my day to day practice as a neurologist I see a not insubstantial number of people who are young and have stroke.听 But this chimed with the recent studies from the Global Burden of Disease Study in 2010 that found that of the 17 million or so strokes worldwide each year about five million were in people aged under 64.听 So it鈥檚 a not insubstantial problem.

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Porter

Because the finger was pointed very firmly at the nation鈥檚 expanding waistlines effectively that obesity might be a big factor behind the rise in stroke in men and women in their 40s and 50s?

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Salman

Yes I mean there鈥檚 no doubting that things like diabetes, high cholesterol and obesity are bad for you, not to mention things that we already know are bad for us like smoking and high blood pressure.听 And I share Peter and Margaret鈥檚 concerns about the way the data are acquired but even if the stroke rates in the young are not rising now they may well do in the future, the way the trends and these risk factors are going, so it鈥檚 important and we should talk about it.

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McCartney

We do have really high quality data, for example, from the South London Stroke Register, who made a really excellent study looking at stroke incidents in South London and reported a couple of years ago.听 And they really hand checked all the records of people who were thought to have had strokes, they double checked the workings, they made sure the codes were accurate and they had found that in almost all age groups stroke risk was falling but it was not falling in black people and in younger people, it wasn鈥檛 rising but the problem was it wasn鈥檛 falling like everyone else鈥檚 was.

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Rothwell

In the same way that Margaret mentioned the South London Stroke Register we鈥檝e been doing a similar study in Oxfordshire over the last several decades and we don鈥檛 find an increase in stroke incidents in younger people but we do find that it鈥檚 not going down, whereas it is going down at older ages.听 So there鈥檚 something positive happening at older ages in terms of stroke prevention that isn鈥檛 happening in the 40s and 50s.听 So to that extent I think it is a problem.

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Porter

And that intervention might be what 鈥� I mean are we talking about things like blood pressure control, statins 鈥� the sort of things that we鈥檙e aiming largely at older people in society?

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Rothwell

I think that鈥檚 exactly right, I think blood pressure, or high blood pressure is by far the most important risk factor for stroke, so it鈥檚 the first place to look at.听 And certainly in young and middle aged men we tend not to measure blood pressure, younger women tend to get their blood pressures measured when they go on the pill, when they get pregnant and after they鈥檙e pregnant when they go on HRT but a lot men don鈥檛 get their blood pressure measured at all until they鈥檙e in their fifth or sixth decade.听 So we鈥檙e certainly missing high blood pressure in some younger people.

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McCartney

And I suppose it may be that we鈥檙e able to change the risk factors in older people but perhaps in younger people the risk factors aren鈥檛 things that are so amenable to an intervention.

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Rothwell

I think that鈥檚 exactly right and also the payback for, in the short term, for treating the risk factors in younger people is so much smaller, you have to treat so many thousand people to prevent one stroke in the next few years that the guidelines tend to discourage treatment in younger people.

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Porter

Could part of the increase picked up in this data be due to increased diagnosis, I mean since I鈥檝e qualified in the 鈥�80s we鈥檝e transformed the way we scan and investigate people with suspected stroke, are we simply picking more minor strokes up?

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McCartney

So it鈥檚 interesting that we are using MRI more and more and I think one of the problems with that is that it can pick up small abnormalities that aren鈥檛 actually significant.听 So in 1995 about 12% of people having a stroke had an MRI scan, it鈥檚 now approaching 70%, probably more by now.听 And one of the problems can be that we know that there鈥檚 lots of small abnormalities that can be picked up that could end up being coded as a stroke but actually never were, these are kind of false positives.

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Porter

The argument being, Rustam, being that these would have been missed previously but if we hadn鈥檛 had MRI you鈥檇 never have picked it up?

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Salman

Yes well I鈥檝e been sitting here quietly in Edinburgh listening to you talking about MRI and my blood pressure鈥檚 been slowly rising while you鈥檝e been doing that.听 And the reason for that, as Margaret says, is that MRI is more and more widely available and when it鈥檚 appropriately used that鈥檚 absolutely fine but it鈥檚 increasingly being inappropriately used and it鈥檚 also being used for profit in the commercial sector for health screening.

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Porter

And the results of that are what?

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Salman

Well we know that about 2.7% of the general population who have no symptoms relating to their brain whatsoever harbour some kind of completely incidental abnormality in their brain.听 And if you鈥檙e a gambler you鈥檒l know that there are 37 pockets in a roulette wheel, so one in 37 is 2.7%.听 So if you鈥檙e having a brain MRI scan without any neurological symptoms you鈥檙e playing roulette with finding an abnormality that you might wish had never been found.听 The main problem with these abnormalities is that many of them may one day cause a stroke but a vast number of them never cause a stroke.听 So the dilemma when it鈥檚 found is you may leave somebody who don鈥檛 treat to try and prevent a stroke worried that one day this time bomb in their head might bleed and then you may cause harm from treating them for the other people who you try to prevent a stroke in.

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Porter

So when we鈥檙e talking about abnormalities we鈥檙e not talking about necessarily scars that might have been an old injury, we鈥檙e talking about blood vessels that might let go and cause a bleed?

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Salman

Yes exactly, so for example something like an aneurysm, which is an area of weakening in a blood vessel wall, it forms a small pouch on an artery where high pressure blood鈥檚 carried into the brain and might one day burst.听 But we know there鈥檚 a very large number of people in the population have these and they never bleed.听 So the dilemma is should you have treatment to prevent them bleeding or not?

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Porter

And Peter, presumably, we have no clever way of working out who鈥檚 likely to bleed and who鈥檚 not, so once we鈥檝e identified it we have to do something?

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Rothwell

It鈥檚 very difficult, that鈥檚 right, and there鈥檚 often no surprisingly a pressure from the patient themselves, they don鈥檛 want to live with this abnormality knowing that it might bleed.听 And so sometimes clinicians are forced into thinking about procedures that carry a significant risk themselves to try and treat these lesions but in a patient who may very well never have had a problem with it.

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McCartney

The other problem is that quite often MRI scans will come back and they鈥檒l show small dots, tiny lesions, and we see this a lot in reports that we get sent back to us and the question is always whether or not that has been a tiny, tiny stroke or whether there鈥檚 been some kind of damage done.听 And I think the problem is as we do more and more MRI scans we鈥檙e going to pick up more and more and more small abnormalities and there鈥檚 a coding dilemma, does that person have a problem or not, and is that person really at increased risk in the future.听 And I think these are very, very difficult questions to answer.

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Porter

Margaret McCartney, Peter Rothwell and Rustam Al-Shahi Salman thank you all very much.

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Now onto something that is dear to your heart Margaret - but what might it be doing to your heart?

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Along with a growing number of other people Margaret enjoys open water swimming - the latest sporting craze to sweep the UK.听 And whether you prefer lochs, lakes, rivers or the sea, there is likely to be one unifying factor - the water is cold and the shock can have some surprising effects on your body.

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So, is it best to edge in slowly? Or plunge in like this?

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[Splash]

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So to show me what鈥檚 involved Margaret鈥檚 brought me down to King鈥檚 Pond, which is an open air pond just behind King鈥檚 Cross in London.听 As you can probably hear it鈥檚 pretty blowy, it鈥檚 14 degrees outside and I鈥檝e just noticed on the blackboard over there, Margaret, it鈥檚 14.2 degrees in the pool, so that will be positively balmy.听

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McCartney

Absolutely and much warmer than Loch Lomond I hope.

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Porter

Now 鈥� so let鈥檚 go in shall we 鈥� I say us, of course someone鈥檚 got to stay on the side and look after the equipment, so鈥�

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McCartney

Oh Mark you wouldn鈥檛.

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Porter

If you go first I鈥檒l see what happens.听 In you go.

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McCartney

Okay, Okay.听 Okay so this is just this - wooden steps, I鈥檓 just lowering myself centimetre by frozen centimetre.听 It鈥檚 quite cold.听 [Laughter]

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Porter

I think you鈥檙e going to have to take the plunge.

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McCartney

Oh no you need to acclimatise Mark, you can鈥檛 go in straightaway.

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Porter

Looks like torture to me.

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McCartney

You just need to keep going in very slowly and tell yourself it鈥檚 going to be lovely, it鈥檚 all about the tingle factor.

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Porter

Go on Margaret you鈥檙e nearly there.听 Oh no back out again, back to her knees.听 This is the slowest geta in I鈥檝e ever seen.

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McCartney

At least I am getting in the water鈥�

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Porter

Yeah, yeah I know I would 鈥� you know I would if I had my kit with me.听 Oooh oooh here we go and she鈥檚 in.

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McCartney

Once you鈥檙e in you do have to keep moving because you get colder and colder and unless you鈥檙e moving you鈥檒l just get too cold and you鈥檒l stop swimming altogether.

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Porter

How does this feel compared to what you鈥檙e normally 鈥� swimming in the loch?

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McCartney

Well Loch Lomond is usually a bit colder actually.听 This is feeling pretty good now.听 Two minutes in and it鈥檚 absolutely lovely.

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Porter

Out you get that鈥檚 beyond the call of duty.

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McCartney

Oh that was fantastic, I feel absolutely fantastic, I鈥檓 just tingling all over.

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Porter

There you go, there鈥檚 your towel.

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McCartney

Thank you Dr Porter.

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Porter

You can have a nice cold shower now to warm up.

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McCartney

Well that was great though, I do feel fantastic afterwards, you feel really alive.

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Porter

You may feel alive but you look very cold.

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McCartney

Off for my cold shower now.

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Porter

Back in the warmth of the studio now.听 Well that obviously invigorated Margaret but it can sometimes have the opposite effect.

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The shock of diving into cold water has long been known to precipitate cardiac arrest in exceptional circumstances, but recent research suggests that potentially serious disturbances in heart rhythm are actually far more common than previously thought. Professor Mike Tipton runs the Extreme Environments Laboratory and joins us on the line.听 So Mike what happens when we enter cold water?

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Tipton

Well you stimulate the cold receptors that are just below the surface of the skin and that sends lots of information to the brain to make you get away from that situation.听 And one of those things is to stimulate the heart, so it鈥檚 part of what we call the cold shock response, there鈥檚 a drive and the heart beats faster.听 However, if at the same time you happen to get the face wet then you stimulate another response which is the diving response, stimulated by receptors around the nose and mouth, that tries to slow the heart, it鈥檚 the response which diving mammals have that allows them to go under the water for a prolonged period.听 So you鈥檝e now have got this confused input to the heart, you鈥檝e got this conflict between one part of the body trying to make it go faster and another part trying to make it go slower and we think it鈥檚 the source of dysrhythmia and arrhythmia on initial immersion.听 Now we鈥檝e seen this in 80% of people that we put into the water that coincidentally get their face and the rest of their body wet and cold.

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Porter

And are these worrying arrhythmias?

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Tipton

Well on the whole they鈥檙e not but we think with predisposing factors 鈥� heart disease 鈥� that they can actually be the precursor to more serious.听 And also there are a significant number of people who are otherwise thought to be fit and healthy who suffer sudden cardiac death.听 So, for example, 80% of those that die in triathlons do so during the swim and the evidence is that this is probably a cardiac related problem.

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Porter

So going back to Margaret getting into her cold Loch Lomond, the way I always get into cold water is 鈥� I鈥檓 embarrassed to say 鈥� is I dive in, get it over and done with, but what you鈥檙e saying that might be the worst thing to do?

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Tipton

Yeah well the cold receptors respond the faster they鈥檙e stimulated.听 So it鈥檚 better to go in slow.

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Porter

Margaret, when you鈥檙e swimming at your Loch, I mean looking around at the people that are swimming, that you鈥檝e seen up there, I mean are most people doing what you do and that鈥檚 getting in very slowly?

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McCartney

No that would be the ducks Mark.

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Porter

And you鈥檝e always got in slowly?

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McCartney

I鈥檝e always got in slowly because then I feel confident.

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Porter

Nothing to do with some inside knowledge about the fact that your heart may be 鈥�. Were you even aware that these arrhythmias existed or were so common?

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McCartney

Well I had heard about them, but I suppose the biggest thing that I鈥檝e always been worried about was the gasp response, you know if you鈥檙e go in too quickly you end up swallowing water that comes in a wave over your head that you鈥檙e not expecting, you do start to breathe faster and faster when you go into cold water and it takes a few minutes for that to settle down.

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Tipton

By far the biggest killer for people going into cold water is that gasp response and a consequence of that is drowning.

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Porter

And this is the classic response that everyone will be familiar with 鈥� it鈥檚 the [gasping] as you go in鈥�

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Tipton

That鈥檚 right鈥�

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Porter

鈥� to the water.

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Tipton

Absolutely it鈥檚 a big gasp of about one to one and a half litres of air, which in itself is enough, if you happen to be under the water, you have a wave breaking over your face.

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McCartney

I think one of the big issues when you鈥檙e swimming is that you can cool and cool and cool and then we you get out you can cool even more and one of the problems you can get is when you鈥檙e cooling down your blood circulation is going centrally, so it鈥檚 going to keep your organs warm and it鈥檚 not going to your muscles, so your muscles get tired, you get clumsy.听 And I have seen some people struggling to get out because they鈥檙e cooling down, they don鈥檛 have much blood volume in their muscles anymore and it鈥檚 really hard for them to get the strength to actually get to a safe place again.

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Tipton

Once you鈥檝e cooled the skin, which gives you the cold shock response, which disappears in a couple of minutes as the skin receptors adapt, then the next hazardous period is exactly what we鈥檝e just heard, which is the cooling of the superficial muscles and nerves where they just become dysfunctional, you become physically incapacitated, that鈥檚 when swim failure occurs.听 So if you鈥檙e going to go cold water swimming the smart thing to do is to habituate that cold shock response, which you can do, and then don鈥檛 stay in for more than about 20 minutes, by which time you鈥檒l start to feel that peripheral incapacitation but that鈥檚 still before you鈥檝e become hypothermic, by the classic definition.

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Porter

Margaret, we should say that 鈥� we鈥檙e concentrating on the heart and on cooling 鈥� but that鈥檚 not the only thing you need to bear in mind, just last weekend we had a couple of deaths in people who were near a waterfall but there are other hazards as well you need to bear in mind.

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McCartney

I鈥檓 a very risk adverse open water swimming and I tend to make sure that my environment is very, very safe.听 So the King鈥檚 Pond pool was ideal for me because I think we had the luxury of two lifeguards, one small pond and Dr Porter, who had forgotten his swimsuit.

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Porter

Yes a very attendant doctor on the side-lines there.听 Mike, as you can probably gather, I鈥檓 being teased for not joining Margaret in that rather cold pool but did you actually cold water swim yourself?

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Tipton

I鈥檝e just this morning been into the sea off the coast of Perranporth, where I think the water temperature was about 10 degrees Celsius.听 However, I made sure I was wearing a four millimetre wet suit which I felt very good about until a lady walked past me in a bikini, which I hastily left the sea and ran back to my car at that point.

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Porter

Professor Mike Tipton, thank you very much. And Margaret it would seem your slow approach to getting in does make physiological sense - even though it prolongs the agony.

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If there is something you would like us to look into, or a health issue that is confusing you, then please do get in touch. You an email us at insidehealth@bbc.co.uk or tweet me @drmarkporter

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One area that seems to confuse lots of people is the terminology used to report research so - with the help of Carl Heneghan, who鈥檚 Professor of Evidence Based Medicine at the University of Oxford, we have produced a series of guides over the coming weeks to help steer you through the maze.

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First up causation versus association. 听Research may show, for instance, that people with lower than average vitamin D levels are more likely to get bowel cancer, but that does not mean that boosting levels of the vitamin will protect against the disease. Although that鈥檚 an easy assumption to make.

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McCartney

I鈥檓 going to tell you a story.听 A few months ago my children, my two youngest, were trying to learn how to do handstands and my little boy got it.听 And then the following day they tried to do it again and this day he couldn鈥檛 do the handstands but he was going upstairs and I said 鈥� Oh what are you going to get?听 He said 鈥� I鈥檓 going to get my yellow socks because I had my yellow socks on yesterday and I could do my handstands and I can鈥檛 do them today but if I put my yellow socks on I鈥檒l be able to do it.听 Now he was able to do his handstands in his yellow socks but the point was that it wasn鈥檛 the yellow socks that caused him to do it and that鈥檚 the difference between association and causation.听 The association was between doing the handstands while wearing yellow socks but the yellow socks did not cause him being able to do his handstands.

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Porter

Carl, this is a perennial problem for people analysing research results, trying to work out what鈥檚 doing what to whom.

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Heneghan

Well I鈥檒l give you an example which is probably a really relevant clinical problem.听 Let鈥檚 take lung cancer.听 We know that smoking causes lung cancer, we follow doctors, 40,000 of them, a very important study by Richard Doll for 50 years to show that smoking causes lung cancer and if you smoke on average you reduce your life expectancy by about 10 years.听 However, you can look at a group of people like people who are disadvantaged or socially deprived and also say 鈥� come up with a similar answer 鈥� people are socially deprived, that causes lung cancer.听 But it doesn鈥檛, it鈥檚 associated with lung cancer.听 Why is it associated?听 People who are social deprived are less well off, smoke more and then in smoking more you then cause a cancer.听 So that鈥檚 what鈥檚 the difference between something that causes something and something that鈥檚 associated with the causative agent.听 What鈥檚 very difficult and we see in all the headlines is disentangling causation from association.

听

McCartney

I think someone got a t-shirt for me once saying 鈥渁ssociation is not causation鈥� because it is so important.听 And so many media stories, press stories, are out sort of saying this vitamin is associated with that outcome, drinking wine is associated with breast cancer, x causes y and the problem is that it鈥檚 very, very easy to do these association kind of studies, it鈥檚 usually questionnaire studies asking people about their habits, their behaviours and their diet and then you follow these people up and you see what happened to them and you say well that was related to that.听 But the problem is that does not equal that, that鈥檚 the issue.

听

Heneghan

I guess that鈥檚 one aspect.听 The second aspect is there鈥檚 a new term called Big Data that allows people to just trawl databases, be a bit sloppy, do something called retrospective, instead of going forward in time go backwards and say ooh I鈥檝e found something.听 And the media love it and we have all this news in the morning going 鈥� Oh we鈥檝e just found out red wine does this for you 鈥� and it carries on and on and that鈥檚 pretty sloppy research.

听

Porter

Well okay let鈥檚 use the red wine as an example.听 Let鈥檚 say there鈥檚 a new study out tomorrow that shows that drinking claret reduces your risk of getting heart disease.听 How do I know, as a reader, that that鈥檚 not because people who tend to drink claret tend to be better off and therefore might be less likely to smoke, be more active, eat more healthily or whatever.听 I mean are the researchers taking that into consideration generally?

听

Heneghan

Well they try to do that with some methodological adjustments but the default is this is an association until proven otherwise.听 So, for instance, the fact is you drink your red claret, you could even look at the cost of the claret and say actually people who drink high quality wine, the association might be you鈥檙e better off, you exercise more, you don鈥檛 smoke and all these features are what are giving you the life expectancy gain.听 And so we could probably do a study and probably prove that high cost wine reduces your mortality on that basis but it wouldn鈥檛 be the higher cost wine, it鈥檚 the association.听 So my default would always be this is an association until proven otherwise.

听

Porter

So Margaret, once again, going back to what our listeners should do when they鈥檙e reading these stories in the media they should be asking themselves this question鈥�

听

McCartney

Yeah absolutely.

听

Porter

鈥� is this causation or is it association?

听

McCartney

Association and association studies tend to be鈥�

听

Porter

Because it might not always be pointed out to them might it by journalists.

听

McCartney

鈥� and I have to say that I鈥檝e been back to several authors of press releases sort of pointing out that I don鈥檛 think you鈥檝e made it clear enough in your headline that this is an association that you鈥檝e found rather than a causation and it鈥檚 a really important thing because the press love it, as Carl was saying, and it can be very difficult to disentangle association and causation.听 So we have to be really clear.

听

Porter

Margaret McCartney and Professor Carl Heneghan with the first of our terminology guides. And we will be covering other confusing terms - like relative risk, absolute mortality and statistical significance - throughout the series.

听

Just time to tell you about next week鈥檚 programme when I visit Southampton to meet the team behind a new approach to treating enlarged prostates, and thermometers - which ones should you be using, and which ones you shouldn鈥檛.

听

Ends