Occasional reflections on Life, the World, and Mathematics

Posts tagged ‘public health’

Obesity and cancer

The Guardian has prominently posted a report by Cancer Research UK with a frightening headline:

Obesity to eclipse smoking as biggest cause of cancer in UK women by 2043

That’s pretty sensational. I was intrigued, because the mortality effects of obesity have long intrigued me. It seems like I’ve been hearing claims for decades, loudly trumpeted in the press, that obesity is turning into a health crisis, with the mortality crisis just around the corner. It seems plausible, and yet every time I try to dig into one of these reports, to find out what the estimates are based on, I come up empty. Looking at the data naively, it seems that the shift from BMI 20 to BMI 25 — the threshold of official “overweight” designation — has been associated in the past with a reduction in all-cause mortality. Passing through overweight to “obesity” at BMI 30 raises mortality rates only very slightly. Major increases in mortality seem to be associated with BMI over 35 or 40, but even under current projections those levels remain rare in nearly all populations.

There is a chain of reasoning that goes from obesity to morbid symptoms like high blood pressure and diabetes, to mortality, but this is fairly indirect, and ignores the rapid improvement in treatments for these secondary symptoms, as well as the clear historical association between increasing childhood nutrition and improved longevity. Concerned experts often attribute the reduction in mortality at low levels of “overweight” to errors in study design — such as confusing weight loss due to illness with healthy low weight — which has indeed been a problem and negative health consequences attributable to weight-loss diets tend to be ignored. All in all, it has always seemed to be a murky question, leaving me genuinely puzzled by the quantitative certainty with which catastrophe is predicted. Clearly increasing obesity isn’t helping people’s health — the associated morbidity is a real thing, even if it isn’t shortening people’s lives much — but I’m perplexed by the quantitative claims about mortality.

So, I thought, if obesity is causing cancer, as much as tobacco is, that’s a pretty convincing piece of the mortality story. And then I followed up the citations, and the sand ran through my fingers. Here are some problems:

  1. Just to begin with, the convergence of cancers attributable to smoking with cancers attributable to obesity is almost entirely attributable to the reduction in smoking. “By 2043 smoking may have been reduced to the point that it is no longer the leading cause of cancer in women” seems like a less alarming possible headline. Here’s the plot from the CRUK report:
    Screenshot 2018-09-24 11.48.43
  2. The report entirely conflates the categories “overweight” and “obese”. The formula they cite refers to different levels of exposure, so it is likely they have separated them out in their calculations, but it is not made clear.
  3. The relative risk numbers seem to derive primarily from this paper. There we see a lot of other causes of cancer, such as occupation, alcohol consumption, and exposure to UV radiation, all of which are of similar magnitude to weight. Occupational exposure is about as significant for men as obesity, and more amenable to political control, but is ignored in this report. Again, the real story is that the number of cancers attributable to smoking may be expected to decline over the next quarter century, to something more like the number caused by multiple existing moderate causes.
  4.  Breast cancer makes up a huge part of women’s cancer risk, hence a huge part of the additional risk attributed to overweight, hence presumably makes up the main explanation for why women’s additional risk due to overweight is so much higher than men’s. The study seems to estimate the additional breast cancer risk due to smoking at 0. This seems implausible. No papers are cited on breast cancer risk and smoking, possibly because of the focus on British statistics, but here is a very recent study finding a very substantial increase. And here is a meta-analysis.
  5. The two most common cancers attributable to obesity in women — cancer of the breast and uterus — are among the most survivable, with ten-year survival above 75%. (Survival rates here.) The next two on the list would be bowel and bladder cancer, with ten-year survival above 50%. The cancer caused by smoking, on the other hand, is primarily lung cancer, with ten-year survival around 7%, followed by oesophageal (13%), pancreatic (1%), bowel and bladder. Combining all of these different neoplasms into a risk of “cancer”, and then comparing the risk due to obesity with that due to smoking, is deeply misleading.

UPDATE: My letter to the editor appeared in The Guardian.

Male nurses and politically incorrect comments on gender

I was just reading this article by journalist Conor Friedersdorf, complaining about how Canadian psychologist Jordan Peterson is being unfairly treated by journalists, who try to twist his subtle anti-feminist arguments into crude anti-feminist slurs. He certainly has a point. But then one comes to comments like this

[Interviewer]: Is gender equality desirable?

Peterson: If it means equality of outcome then it is almost certainly undesirable. That’s already been demonstrated in Scandinavia. Men and women won’t sort themselves into the same categories if you leave them to do it of their own accord. It’s 20 to 1 female nurses to male, something like that. And approximately the same male engineers to female engineers. That’s a consequence of the free choice of men and women in the societies that have gone farther than any other societies to make gender equality the purpose of the law. Those are ineradicable differences––you can eradicate them with tremendous social pressure, and tyranny, but if you leave men and women to make their own choices you will not get equal outcomes.

20 to 1? That seems really high. For nurses and for engineers. So I decided to do something rude, and check the numbers. For nurses, I found these statistics. There’s a lot of variation in Scandinavia. In Denmark it seems like about 20:1 female to male. But in Norway it’s 9:1. In Iceland it’s 100:1. Looking further afield, in Israel and Italy 20% of nurses are male. And in the Netherlands nearly 25%. This does not look like an ineradicable difference to me. It looks like path dependence and social context.

What about engineers? Here Peterson is, to use the technical term, talking out of his ass. There is no country in the EU with such an extreme gender imbalance for engineers: The most extreme is the UK, with about a 10:1 male to female ratio. In Sweden it’s 3:1, in Norway 4:1, and in Denmark 5:1. In Latvia the fraction of female engineers is up to 30%.

I think, if you want to make provocative “I’m just trying to be rational here” public arguments, you kind of have an obligation not to make up your supporting facts.

Overt public blackmail?

Just when you thought you’d reached the bottom of the we’re-being-governed-by-toddlers-who-missed-a-nap slough of despond, they manage to surprise you again. This time, it’s the Chancellor of the Exchequer  Philip Hammond, who decided to punish the NHS (and, by proxy, the entire English public) for the brazenness of its chief, Simon Stevens. Stevens gave a speech two weeks ago, saying the NHS is on the verge of financial collapse, and since the one thing that’s clear about the result of the Brexit referendum is that the public likes the idea of giving £350 million a week more to the NHS, maybe the government should just go ahead and do that. Instead,

Philip Hammond backtracked on plans to give the NHS more money than it eventually got in the budget after reacting with “fury” to its boss Simon Stevens’s public demand for an extra £4bn next year.

Since I am always particularly intrigued by political semantics, I was struck by this line:

Hammond and Treasury officials felt that the NHS England chief executive’s move meant that the chancellor could not be seen to be acceding to what they saw as “overt public blackmail”

What I wonder is, is there such a thing as “overt public blackmail”? Blackmail is when you make secret demands, with the threat to publicly embarrass the target by revealing hidden information. It’s not even any kind of extortion, which would mean issuing threats to force someone into a desired course of action. The only threat Stevens made is that without more money the NHS faces collapse. Warning someone of the potential consequences of their actions is neither extortion nor blackmail. And saying, we agree with the analysis, but since we don’t want to look like we’re agreeing with you, we’re going to do the opposite, is something so stupid that I don’t think  there is a specific name for it. (Maybe the Piranha Brothers used that technique?)

Now, what would be blackmail? How about telling the head of an independent government agency in private talks that his agency and the whole population are being throttled for his presumptuous public speech, not needing to say explicitly that a deferential turn might prevent future punishment — well, I guess that’s extortion.

Maybe someone should give him a cookie?

NHS hit by unforeseen Earth tilt

A critical government service has to be prepared for all foreseeable contingencies. But sometimes the unpredictable occurs, and bureaucrats can fall into panic.

A tilt in the Earth’s axis that no one could have foreseen is apparently causing daylight to grow shorter in northern latitudes and temperatures to drop, leading to an increase in communicable diseases and accidents that threatens to overwhelm NHS emergency services. Or, in other words,

Disclosure of NHS England’s attempt to impose a detailed series of duties on hospitals comes amid claims by senior insiders that its leadership is in a state of panic over winter.

The people let down the NHS

I saw this headline in the Daily Mail yesterday:

Pity the poor NHS. Doing its job perfectly, but being cruelly let down by the shiftless population. To paraphrase Bertolt Brecht, perhaps it would be better were the NHS to carry out a root-and-branch reform of the British public. Eliminate waste. Get rid of the dead wood.

NHS wants you! (to spread the varicella virus)

I’ve long wondered why children in Britain generally don’t get the chickenpox vaccine. In an article describing a move by drugstores to offer the vaccine for a substantial fee, the BBC quotes the NHS:

The NHS said a chickenpox vaccine is not offered as part of routine immunisations as it would leave unvaccinated children more susceptible to contracting the virus as an adult.

There could also be a significant increase in shingles cases as being exposed to infected children boosts immunity to this.

This is like the cracked-mirror reflection of the usual herd-immunity argument for why, even if you don’t want vaccines for yourself or your children, you have a civic obligation to make yourself immune to avoid transmitting the virus to others. Here they say that children have a duty to suffer with an unpleasant disease, so that they can serve as walking virus reservoirs that will more efficiently infect other children, and boost the immunity of adults.

I suppose there’s a cost-benefit analysis somewhere that shows this is the cheapest approach. And I’d bet that the cost of children’s discomfort is set at zero.

“A triumph of personal bias over research”

The Guardian reports on a new research study that finds the overstretching of the NHS — particularly in the winter — has caused about 30,000 excess deaths in 2015. The government’s response is practically Trumpian:

A DH spokesman described the study as “a triumph of personal bias over research”. He added: “Every year there is significant variation in reported excess deaths, and in the year following this study they fell by nearly 20,000, undermining any link between pressure on the NHS and the number of deaths. Moreover, to blame an increase in a single year on ‘cuts’ to the NHS budget is arithmetically impossible given that budget rose by almost £15bn between 2009-10 and 2014-15.”

Demeaning experts who bring unpleasant news is the primary tactic. (more…)

CDC works toward the president

Dem Führer entgegenarbeiten — Working toward the Leader — was one of the most important neologisms of the early Third Reich. No one really knew what Hitler wanted to do — not even Hitler himself — and the organs of state were in turmoil, certainly incapable of providing rapid guidance at the local level to the government’s plans. So everyone’s obligation was to surmise what the Führer’s ultimate objectives were, and work toward accomplishing it, without needing specific instructions.

Compare that to these recent decisions of the completely apolitical Centers for Disease Control and Prevention:

CDC abruptly cancels long-planned conference on climate change and health

The Climate and Health Summit, which had been in the works for months, was intended as a chance for public health officials around the country to learn more about the mounting evidence of the risks to human health posed by the changing climate. But CDC officials abruptly canceled the conference before President Trump’s inauguration, sending a terse email on Jan. 9 to those who had been scheduled to speak at the event. The message did not explain the reason behind the decision.

CDC Indefinitely Postponed LGBT Youth Health Summit After Election

To be fair, the reason seems to be that they needed the resources to focus on their conference on disease transmission by refugees and illegal immigrants.

 

Warnings

Suppose your football coach exhorts the team with all the great coach clichés: “We win or lose together”, “There’s no I in ‘Team'”, maybe “We can still win if we pull together and give 110 percent in the second half”. Would anyone say this was a “warning”? But when Angela Merkel says Europe needs to work together to deal with the current influx of migrants, we get this headline in the Guardian:

 

guardian_merkel

It reminds me of the peculiar set of mandatory texts that were introduced for cigarette packets in the US in 1981: Among the warnings of carbon monoxide and foetal injury was this one:

SURGEON GENERAL’S WARNING: Quitting Smoking Now Greatly Reduces Serious Risks to Your Health.

“Greatly reduces serious risks to your health” doesn’t sound like a warning to me.

I didn’t even know it was a strategy…

Headline in today’s Times:

Obesity Strategy ‘is Failing’

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