Category Archives: Public health

Correlation does not equal causation, Dodgy reporting, Public health

The Independent’s anti-vaccine scaremongering

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Last weekend The Independent published a ridiculous piece of antivaccine scaremongering by Paul Gallagher on their front page. They report the story of girls who became ill after receiving HPV vaccine, and strongly imply that the HPV vaccine was the cause of the illnesses, flying in the face of massive amounts of scientific evidence to the contrary.

I could go on at length about how dreadful, irresponsible, and scientifically illiterate the article was, but I won’t, because Jen Gunter and jdc325 have already done a pretty good job of that. You should go and read their blogposts. Do it now.

Right, are you back? Let’s carry on then.

What I want to talk about today is the response I got from the Independent when I emailed the editor of the Independent on Sunday, Lisa Markwell, to suggest that they might want to publish a rebuttal to correct the dangerous misinformation in the original article. Ms Markwell was apparently too busy to reply to a humble reader, so my reply was from the deputy editor, Will Gore.  Here it is below, with my annotations.

Dear Dr Jacobs

Thank you for contacting us about an article which appeared in last weekend’s Independent on Sunday.

Media coverage of vaccine programmes – including reports on concerns about real or perceived side-effects – is clearly something which must be carefully handled; and we are conscious of the potential pitfalls. Equally, it is important that individuals who feel their concerns have been ignored by health care professionals have an outlet to explain their position, provided it is done responsibly.

I’d love to know what they mean by “provided it is done responsibly”. I think a good start would be not to stoke anti-vaccine conspiracy theories with badly researched scaremongering. Obviously The Independent has a different definition of “responsibly”. I have no idea what that definition might be, though I suspect it includes something about ad revenue.

On this occasion, the personal story of Emily Ryalls – allied to the comparatively large number of ADR reports to the MHRA in regard to the HPV vaccine – prompted our attention. We made clear that no causal link has been established between the symptoms experienced by Miss Ryalls (and other teenagers) and the HPV vaccine. We also quoted the MHRA at length (which says the possibility of a link remains ‘under review’), as well as setting out the views of the NHS and Cancer Research UK.

Oh, seriously? You “made it clear that no causal link has been established”? Are we even talking about the same article here? The one I’m talking about has the headline “Thousands of teenage girls enduring debilitating illnesses after routine school cancer vaccination”. On what planet does that make it clear that the link was not causal?

I think what they mean by “made it clear that no causal link has been established” is that they were very careful with their wording not to explicitly claim a causal link, while nonetheless using all the rhetorical tricks at their disposal to make sure a causal link was strongly implied.

Ultimately, we were not seeking to argue that vaccines – HPV, or others for that matter – are unsafe.

No, you’re just trying to fool your readers into thinking they’re unsafe. So that’s all right then.

Equally, it is clear that for people like Emily Ryalls, the inexplicable onset of PoTS has raised questions which she and her family would like more fully examined.

And how does blaming it on something that is almost certainly not the real cause help?

Moreover, whatever the explanation for the occurrence of PoTS, it is notable that two years elapsed before its diagnosis. Miss Ryalls’ family argue that GPs may have failed to properly assess symptoms because they were irritated by the Ryalls mentioning the possibility of an HPV connection.

I don’t see how that proves a causal link with the HPV vaccine. And anyway, didn’t you just say that you were careful to avoid claiming a causal link?

Moreover, the numbers of ADR reports in respect of HPV do appear notably higher than for other vaccination programmes (even though, as the quote from the MHRA explained, the majority may indeed relate to ‘known risks’ of vaccination; and, as you argue, there may be other particular explanations).

Yes, there are indeed other explanations. What a shame you didn’t mention them in your story. Perhaps if you had done, your claim to be careful not to imply a causal link might look a bit more plausible. But I suppose you don’t like the facts to get in the way of a good story, do you?

The impact on the MMR programme of Andrew Wakefield’s flawed research (and media coverage of it) is always at the forefront of editors’ minds whenever concerns about vaccines are raised, either by individuals or by medical studies. But our piece on Sunday was not in the same bracket.

No, sorry, it is in exactly the same bracket. The media coverage of MMR vaccine was all about hyping up completely evidence-free scare stories about the risks of MMR vaccine. The present story is all about hyping up completely evidence-free scare stories about the risk of HPV vaccine. If you’d like to explain to me what makes those stories different, I’m all ears.

It was a legitimate item based around a personal story and I am confident that our readers are sophisticated enough to understand the wider context and implications.

Kind regards

Will Gore
Deputy Managing Editor

If Mr Gore seriously believes his readers are sophisticated enough to understand the wider context, then he clearly hasn’t read the readers’ comments on the article. It is totally obvious that a great many readers have inferred a causal relationship between the vaccine and subsequent illness from the article.

I replied to Mr Gore about that point, to which he replied that he was not sure the readers’ comments are representative.

Well, that’s true. They are probably not. But they don’t need to be.

There are no doubt some readers of the article who are dyed-in-the-wool anti-vaccinationists. They believed all vaccines are evil before reading the article, and they still believe all vaccines are evil. For those people, the article will have had no effect.

Many other readers will have enough scientific training (or just simple common sense) to realise that the article is nonsense. They will not infer a causal relationship between the vaccine and the illnesses. All they will infer is that The Independent is spectacularly incompetent at reporting science stories and that it would be really great if The Independent could afford to employ someone with a science GCSE to look through some of their science articles before publishing them. They will also not be harmed by the article.

But there is a third group of readers. Some people are not anti-vaccine conspiracy theorists, but nor do they have science training. They probably start reading the article with an open mind. After reading the article, they may decide that HPV vaccine is dangerous.

And what if some of those readers are teenage girls who are due for the vaccination? What if they decide not to get vaccinated? What if they subsequently get HPV infection, and later die of cervical cancer?

Sure, there probably aren’t very many people to whom that description applies. But how many is an acceptable number? Perhaps Gallagher, Markwell, and Gore would like to tell me how many deaths from cervical cancer would be a fair price to pay for writing the article?

It is not clear to me whether Gallagher, Markwell, and Gore are simply unaware of the harm that such an article can do, or if they are aware, and simply don’t care. Are they so naive as to think that their article doesn’t promote an anti-vaccinationist agenda, or do they think that clicks on their website and ad revenue are a more important cause than human life?

I really don’t know which of those possibilities I think is more likely, nor would I like to say which is worse.

Dodgy reporting, Dodgy statistics, Economics, Public health

Is smoking plunging children into poverty?

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If we feel it necessary to characterise ourselves as being “pro” or “anti” certain things, I would unambiguously say that I am anti-smoking. Smoking is a vile habit. I don’t like being around people who are smoking. And as a medical statistician, I am very well aware of the immense harm that smoking does to the health of smokers and those unfortunate enough to be exposed to their smoke.

So it comes as a slight surprise to me that I find myself writing what might be seen as a pro-smoking blogpost for the second time in just a few weeks.

But this blogpost is not intended to be pro-smoking: it is merely anti the misuse of statistics by some people in the anti-smoking lobby. Just because you are campaigning against a bad thing does not give you a free pass to throw all notions of scientific rigour and social responsibility to the four winds.

An article appeared yesterday on the Daily Mail website with the headline:

“Smoking not only kills, it plunges children into POVERTY because parents ‘prioritise cigarettes over food'”

and a similar, though slightly less extreme, version appeared in the Independent:

“Smoking parents plunging nearly half a million children into poverty, says new research”

According to the Daily Mail, parents are failing to feed their children because they are spending money on cigarettes instead of food. The Independent is not quite so explicit in claiming that, but it’s certainly implied.

Regular readers of this blog will no doubt already have guessed that those articles are based on some research which may have been vaguely related to smoking and poverty, but which absolutely did not show that any children were going hungry because of their parents’ smoking habits. And they would be right.

The research behind these stories is this paper by Belvin et al. There are a number of problems with it, and particularly with the way their findings have been represented in the media.

The idea of children being “plunged into poverty” came from looking at the number of families with at least one smoker who were just above the poverty line. Poverty in this case is defined as a household income less than 60% of the median household income (taking into account family size). If the amount families above the poverty line spent on cigarettes took their remaining income after deducting their cigarette expenditure below the poverty line, then they were regarded as being taken into poverty by smoking.

Now, for a start, Belvin et al did not actually measure how much any family just above the poverty line spent on smoking. They made a whole bunch of estimates and extrapolations from surveys that were done for different purposes. So that’s one problem for a start.

Another problem is that absolutely nowhere did Belvin et al look at expenditure on food. There is no evidence whatsoever from their study that any family left their children hungry, and certainly not that smoking was the cause. Claiming that parents were prioritising smoking over food is not even remotely supported by the study, as it’s just not something that was measured at all.

Perhaps the most pernicious problem is the assumption that poverty was specifically caused by smoking. I expect many families with an income above 60% of the median spend some of their money on something other than feeding their children. Perhaps some spend their money on beer. Perhaps others spend money on mobile phone contracts. Or maybe on going to the cinema. Or economics textbooks. Or pretty much anything else you can think of that is not strictly essential. Any of those things could equally be regarded as “plunging children into poverty” if deducting it from expenditure left you below median income.

So why single out smoking?

I have a big problem with this. I said earlier that I thought smoking was a vile habit. But there is a big difference between believing smoking is a vile habit and believing smokers are vile people. They are not. They are human beings. To try to pin the blame on them for their children’s poverty (especially in the absence of any evidence that their children are actually going hungry) is troubling. I am not comfortable with demonising minority groups. It wouldn’t be OK if the group in question were, say, Muslims, and it’s not OK when the group is smokers.

There are many and complex causes of poverty. But blaming the poor is really not the response of a civilised society.

The way this story was reported in the Daily Mail is, not surprisingly, atrocious. But it’s not entirely their fault. The research was filtered through Nottingham University’s press office before it got to the mainstream media, and I’m afraid to say that Nottingham University are just as guilty here. Their press release states

“The reserch [sic] suggests that parents are likely to forgo basic household and food necessities in order to fund their smoking addiction.”

No, the research absolutely does not suggest that, because the researchers didn’t measure it. In fact I think Nottingham University are far more guilty than the Daily Mail. An academic institution really ought to know better than to misrepresent the findings of their research in this socially irresponsible way.

Conflicts of interest, Dodgy reporting, Dodgy statistics, Public health

Are strokes really rising in young people?

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I woke up to the news this morning that there has been an alarming increase in the number of strokes in people aged 40-54.

My first thought was “this has been sponsored by a stroke charity, so they probably have an interest in making the figures seem alarming”. So I wondered how robust the research was that led to this conclusion.

The article above did not link to a published paper describing the research. So I looked on the Stroke Association’s website. There, I found a press release. This press release also didn’t link to any published paper, which makes me think that there is no published paper. It’s hard to believe a press release describing a new piece of research would fail to tell you if it had been published in a respectable journal.

The press release describes data on hospital admissions provided by the NHS, which shows that the number of men aged 40 to 54 admitted to hospital with strokes increased from 4260 in the year 2000 to to 6221 in 2014, and the equivalent figures for women were an increase from 3529 to 4604.

Well, yes, those figures are certainly substantial increases. But there could be various different reasons for them, some worrying, others reassuring.

It is possible, as the press release certainly wants us to believe, that the main reason for the increase is that strokes are becoming more common. However, it is also possible that recognition of stroke has improved, or that stroke patients are more likely now to get the hospital treatment they need than in the past. Both of those latter explanations would be good things.

So how do the stroke association distinguish among those possibilities?

Well, they don’t. The press release says “It is thought that the rise is due to increasing sedentary and unhealthy lifestyles, and changes in hospital admission practice.”

“It is thought that”? Seriously? Who thinks that? And why do they think it?

It’s nice that the Stroke Association acknowledge the possibility that part of the reason might be changes in hospital admission practice, but given that the title of the press release is “Stroke rates soar among men and women in their 40s and 50s” (note: not “Rates of hospital admission due to stroke soar”), there can be no doubt which message the Stroke Association want to emphasise.

I’m sorry, but they’re going to need better evidence than “it is thought that” to convince me they have teased out the relative contributions of different factors to the rise in hospital admissions.

Dodgy reporting, Public health

Vaping among teenagers

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Vaping, or use of e-cigarettes, has the potential to be a huge advance in public health. It provides an alternative to smoking that allows addicted smokers to get their nicotine fix without exposing them to all the harmful chemicals in cigarette smoke. This is a development that should be welcomed with open arms by everyone in the public health community, though oddly, it doesn’t seem to be. Many in the public health community are very much against vaping. The reasons for that might make an interesting blogpost for another day.

But today, I want to talk about a piece of research into vaping among teenagers that’s been in the news a lot today.

Despite the obvious upside of vaping, there are potential downsides. The concern is that it may be seen as a “gateway” to smoking. There is a theoretical risk that teenagers may be attracted to vaping and subsequently take up smoking. Obviously that would be a thoroughly bad thing for public health.

Clearly, it is an area that is important to research so that we can better understand what the downside might be of vaping.

So I was interested to see that a study has been published today that looks specifically at smoking among teenagers. Can that help to shed light on these important questions?

Looking at some of the stories in the popular media, you might think it could. We are told that e-cigs are the “alcopops of the nicotine world“, that there are “high rates of usage among secondary school pupils” and that e-cigs are “encouraging people to take up smoking“.

Those claims are, to use a technical term, bollocks.

Let’s look at what the researchers actually did. They used cross sectional questionnaire data in which a single question was asked about vaping: “have you ever tried or purchased e-cigarettes?”

The first thing to note is that the statistics are about the number of teenagers who have ever tried vaping. So they will be included in the statistics if they tried it once. Perhaps they were at a party and they had a single puff on a mate’s e-cig. The study gives us absolutely no information on the proportion of teenagers who vaped regularly. So to conclude “high rates of usage” just isn’t backed up by any evidence. Overall, about 1 in 5 of the teenagers answered yes to the question. Without knowing how many of those became regular users, it becomes very hard to draw any conclusions from the study.

But it gets worse.

The claim that vaping is encouraging people to take up smoking isn’t even remotely supported by the data. To do that, you would need to know what proportion of teenagers who hadn’t previously smoked try vaping, and subsequently go on to start smoking. Given that the present study is a cross sectional one (ie participants were studied only at a single point in time), it provides absolutely no information on that.

Even if you did know that, it wouldn’t tell you that vaping was necessarily a gateway to smoking. Maybe teenagers who start vaping and subsequently start smoking would have smoked anyway. To untangle that, you’d ideally need a randomised trial of areas in which vaping is available and areas in which it isn’t, though I can’t see that ever being done. The next best thing would be to look at changes in the prevalence of smoking among teenagers before and after vaping became available. If it increased after vaping became available, that might give you some reason to think vaping is acting as a gateway to smoking. But the current study provides absolutely no information to help with this question.

I’ve filed post this under “Dodgy reporting”, and of course the journalists who wrote about the study in such uncritical terms really should have known better, but actually I think the real fault lies here with the authors of the paper. In their conclusions, they write “Findings suggest that e-cigarettes are being accessed by teenagers more for experimentation than smoking cessation.”

No, they really don’t show that at all. Of those teenagers who had tried e-cigs, only 15.8% were never-smokers. And bear in mind that most of the overall sample (61.2%) were never-smokers. That suggests that e-cigs are far more likely to be used by current or former smokers than by non-smokers. In fact while only 4.9% of never smokers had tried e-cigs, (remember, that may mean only trying them once), 50.7% of ex-smokers had tried them. So a more reasonable conclusion might be that vaping is helping ex-smokers to quit, though in fact I don’t think it’s possible even to conclude that much from a cross-sectional study that didn’t measure whether vaping was a one-off puff or a habit.

While there are some important questions to be asked about how vaping is used by teenagers, I’m afraid this new study does absolutely nothing to help answer them.

 Update 1 April:

It seems I’m not the only person in the blogosphere to pick up some of the problems with the way this study has been spun. Here’s a good blogpost from Clive Bates, which as well as making several important points in its own right also contains links to some other interesting comment on the study.

 

Economics, Public health

Plain packaging for tobacco

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Plain packaging for tobacco is in the news today. The idea behind it is that requiring tobacco manufacturers to sell cigarettes in unbranded packages, where all the branding has been replaced by prominent health warnings, will reduce the number of people who smoke, and thereby benefit public health.

But will it work?

That’s an interesting question. There’s a lot of research that’s been done, though it’s fair to say none of it is conclusive. For example, there has been research on how it affects young people’s perceptions of cigarettes and on what happened to the number of people looking for help with quitting smoking after plain packaging was introduced in Australia.

But for me, those are not the most interesting pieces of evidence.

What tells me that plain packaging is overwhelmingly likely to be an extremely effective public health measure is that the tobacco industry are strongly opposed to it. They probably know far more about the likely effects than the rest of us: after all, for me, it’s just a matter of idle curiosity, but for them, millions of pounds of their income depends on it. So the fact they are against it tells us plenty.

Let’s look in a little more detail at exactly what it tells us. Advertising and branding generally has 2 related but distinguishable aims for a company that sells something. One aim is to increase their share of the market, in other words to sell more of their stuff than their competitors in the same market. The other is to increase the overall size of the market, so that they sell more, and their competitors sell more as well. Both those things can be perfectly good reasons for a company to spend their money on advertising and branding.

But the difference between those 2 aims is crucial here.

If the point of cigarette branding were just to increase market share without affecting the overall size of the market, then the tobacco industry should be thoroughly in favour of a ban. Advertising and branding budgets, when the overall size of the market is constant, are a classic prisoner’s dilemma. If all tobacco companies spend money on branding, they will all have pretty much the same share as if no-one did, so they will gain nothing, but they will spend money on branding, so they’re worse off than if they didn’t. However, they can’t afford not to spend money on branding, as then they would lose market share to their competitors, who are still spending money on it.

The ideal situation for the tobacco industry in that case would be that no-one would spend any money on branding. But how can you achieve that? For all the companies to agree not to spend money on branding might be an illegal cartel, and there’s always a risk that someone would break the agreement to increase their market share.

A government-mandated ban solves that problem nicely. If all your competitors are forced not to spend money on branding, then you don’t have to either. All the tobacco companies win.

So if that were really the situation, then you would expect the tobacco companies to be thoroughly in favour of it. But they’re not. So that tells me that we are not in the situation where the total market size is constant.

The tobacco companies must believe, and I’m going to assume here that they know what they’re doing, that cigarette branding affects the overall size of the market. If branding could increase the overall size of the market (or more realistically when smoking rates in the UK are on a long-term decline, stop it shrinking quite as fast), then it would be entirely rational for the tobacco companies to oppose mandatory plain packaging.

I don’t know about you, but that’s all the evidence I need to convince me that plain packaging is overwhelmingly likely to be an effective public health measure.