Posts filed under Medical news (328)

July 24, 2016

Disease awareness

One News tonight had a story about venous thromboembolism (VTE) and how people don’t know about it. I couldn’t find a reference for the research, but it wouldn’t surprise me if 50% of people hadn’t heard that term — and many of those who do recognise it might associate it only with long-distance flights.

I can see people wanting to raise awareness, and the story includes a really good animation of what actually happens in a VTE. On the other hand, this is how VTE risk varies with age (source)

Nature Reviews Cardiology 12, 464 (2015). doi:10.1038/nrcardio.2015.83

On top of that, about half of VTE is due to hospitalisation, as the story went on to describe. Given those risk patterns, it’s kind of weird to have the main example in the story be a 20-year-old law student who got a pulmonary embolism without any obvious risk factors.

Disease awareness can be valuable, but it’s probably more useful when it’s modelled on people who are at high, or at least average, risk of the disease.

June 12, 2016

Walking it back

First the headline (Herald, reprinting Daily Telegraph)

Finger-prick test that can show risk of diabetes

then it’s “on the horizon”

The finger-prick test, which could be available at GP surgeries or even chemists, looks for molecules in the blood that indicate diabetes is developing.

but in the present tense. Then

The specific biomarkers involved are being kept a closely guarded secret for now, but once a prototype test has been developed, trials will take place.

This ‘test’ not only hasn’t been evaluated in real patients; it doesn’t even exist yet.

And

Currently, doctors can test for diabetes only by taking blood glucose readings that show whether the disease is already present.

That’s only true if you squint from exactly the right angle. Since 2012, testing for HbA1c, a byproduct of elevated glucose, has been a general screening recommendation in NZ and one of the public health performance indicators. One of the reasons given for screening is

effective screening aims to reduce the incidence of diabetes through detection of people with pre-diabetes

You could argue ‘the disease is already present’ in people with pre-diabetes, but not in the sense that’s relevant to screening.

The current test isn’t all that good, and perhaps when they finish inventing it the new one will be better. But it’s not a test yet; it’s not a ‘health’ story yet; and with so little disclosed information it’s not clear that it’s even a science story yet.

June 3, 2016

Value-added?

From Stuff

Kiwi researchers have come up with a solution to the global obesity epidemic – a bitter plant extract that suppresses appetite.

As you’d expect, calling it “a solution” is completely over the top at the moment. They’ve done a placebo-controlled trial, but lasting less than one day, in only 20 men. The press release is more detailed and more restrained.

What made me mention this story, though, is the numbers. From Stuff

The researchers found that the Amarasate extract stimulated significant increases in hormones that regulate appetite and reduced food intake from 911 kJ (218 calories) to 944 kJ (226 calories).

That sounds incredibly unimpressive: an 8 calorie reduction. It’s wrong, or at least the press release is different and more plausible

.. both gastric and duodenal delivery of the Amarasate™ extract stimulated significant increases in the gut peptide hormones CCK, GLP-1 and PYY while significantly reducing total (lunch plus snack) ad libitum meal energy intake by 911 kJ (218 calories) and 944 kJ (226 calories), respectively.

They looked at two capsules to control where in the gut the stuff was released, and both types reduced calorie intake by a bit more than 200 calories, compared to placebo. The story was off by a factor of 25 or so.

 

 

[update: Those of you who read more carefully than either me or the journalist will have noticed that “reduced .. from 911 kJ .. to 944 kJ ” in the Stuff story is actually an increase, and even less excusable]

[Update next day: The numbers have been fixed —“reduced food intake by up to 944 kJ (226 calories).”  — but not the opening claim. ]

March 14, 2016

Dementia and rugby

Dylan Cleaver has a feature story in the Herald on the Taranaki rugby team who won the Ranfurly Shield in 1964. Five of the 22 have been diagnosed with dementia. Early on in the process he asked me to comment on how surprising that was.

The key fact here is 1964: the five developed dementia fairly young, in their 60s and early 70s. That happens even in people who have no family history and no occupational risks, as I know personally, but it’s unusual.

I couldn’t find NZ data, but I did find a Dutch study (PDF, Table 3) estimating that a man who is alive and healthy at 55 has a 1.5% risk of diagnosed dementia by 70 and 3.2% by 75. There’s broadly similar data from the Framingham study in the US.   The chance of getting 5 or more out of 22 depends on exact ages and on how many died earlier of other causes, but if these were just 22 men chosen at random the chance would be less than 1 in 10,000 — probably much less.  People who know about rugby tell me the fact they were all in the back line is also relevant, and that makes the chance much smaller.

There are still at least two explanations. The first, obviously, is that rugby — at least as played in those days — caused similar cumulative brain damage to that seen in American football players. The second, though, is that we’re hearing about the 1964 Taranaki team partly because of the dementia cases — there wouldn’t have been this story if there had only been two cases, and there might have been a story about some other team instead. That is, it could be a combination of a tragic fluke and the natural human tendency to see patterns.  Statistics is bad at disentangling these; the issue crops up over and over again in cancer surveillance.

In the light of what has been seen in the US, I’d say it’s plausible that concussions contributed to the Taranaki cases.  There have already been changes to the game to reduce repeated concussions, which should reduce the risk in the future. There is also a case for more systematic evaluation of former players, to get a more reliable estimate of the risk, though the fact there’s nothing that can currently be done about it means that players and family members need to be involved in that decision.

March 7, 2016

A good source of iron

Stuff has a story under the lead

Now that it’s autumn, flu season isn’t far off and there’s plenty you could be doing in the kitchen to give your body that extra oomph for the cold months ahead.

Sadly they don’t mean making a phone call to book a flu vaccine shot: they have a list of herbs and spices with unsupported health claims.

Take the first, cinnamon.  Stuff says “It is high in antioxidants, is an anti-inflammatory and has an effect in lowering blood sugar.”  The  National Center for Complementary and Integrative Health , who are about as sympathetic as you can get to this sort of thing “High-quality clinical evidence (i.e., studies in people) to support the use of cinnamon for any medical condition is generally lacking. An analysis of five clinical trials concluded that cinnamon does not appear to affect factors related to diabetes and heart disease.”

Or, for a total failure to do arithmetic, saffron. Stuff says “It is a good source of vitamins, magnesium and iron.” Now, it’s true that saffron is high in nutrients for its weight. A mere 100g of saffron will supply about two-thirds of your daily iron and magnesium, and substantial amounts of vitamins C and B-6. By weight, it does better than spinach. But the typical serving of saffron is a small fraction of a gram, with nutrient contents that would round to zero in any sensible display.

Following the lines of previous StatsChat food advice, I think the photo caption  just needs a bit of editing: “Herbs and spices are an easy way to add healthy elements  flavour to your diet.

(via Mark Hanna and Bart Janssen)

February 29, 2016

‘Cure’ exaggeration

A Herald headline says “Dementia cure just five years away – world expert“. That’s even worse than the Telegraph headline for the original piece “Dementia cure may be just five years away, says world expert“.

The ‘world expert’ is Dennis Gillings, an expert in clinical trials, who is the G8 ‘World Dementia Envoy’, so his opinions are worth listening to. What he says doesn’t really support the headline.

Dr Gillings… said progress was being made on treatments that might halt or reverse the progress of dementia, with some kind of brain training used to help rebuild lost neural pathways.

and

scientists increasingly believed it had been a mistake to treat dementia as one disease, saying it was likely that breakthroughs would come from targeting subtypes of the condition.

and

Saluting recent British investment in science, and the creation of a 150 million Dementia Research Institute, he said that, none the less, breakthroughs were more likely in the US, which put more money into research

If a cure was actually going to be available in five years you would have heard about its success in early clinical trials already. He’s talking about making scientific progress within five years to identify a cure, with breakthroughs still needed.

January 25, 2016

Hangover cure?

“The ‘kudzu’ could cure your hangover”, says the Herald (from the Daily Mail)

We’ve had stories based on unpublished research before. This one is a bit special, because the ‘unpublished research’ is a BBC television programme that won’t be shown for a few days (or, at all, in NZ). And because it didn’t study hangovers or people with hangovers.

The BBC programme is apparently going to report a placebo-controlled crossover trial of how much free booze people drank when they had taken kudzu root extract or a dummy pill — they say they saw a 20% difference. The design is a good one, and given the general theme of the show there probably isn’t much risk of publication bias. Having a reasonably good design fits with seeing a benefit that’s only about half of what was seen in earlier US research.

The big problems with the BBC study are that it’s probably small (the stories don’t say) and doesn’t (so far)give any idea of the uncertainty in the 20% reduction, and that open-bar drinking in a television science experiment may be importantly different from the sort of drinking they’d like to decrease.

As science, the BBC study might actually be ok. But reducing alcohol consumption by 20%, if it does, is unlikely to have a big impact in preventing hangovers. And there is not the slightest suggestion in the research that kudzu root would work as a hangover cure.

 

 

January 21, 2016

Mining uncertainty

The FDA collects data on adverse events in people taking any prescription drugs. This information is, as it should be, available for other uses. I’ve been involved in research using it.

The data are also available for less helpful purposes. As Scott Alexander found,  if you ask Google whether basically anything could cause basically anything, there are companies that make sure Google will return some pages reporting that precise association.  And, as he explains, this is serious.

For example, I tried “Adderall” and “plantar fasciitis” as an implausible combination and got 4 hits based on FDA data. And “Accutane” and “plantar fasciitis”, and “Advair” and “plantar fasciitis”, and “acyclovir” and “plantar fasciitis”. Then I got bored.

It’s presumably true that there are people who have been taking Adderall and at the same time have had plantar fasciitis. But given enough patients to work with, that will be true for any combination of drug and side effect. And, in fact, the websites will happily put up a page saying there are no reported cases, but still saying “you are not alone” and suggesting you join their support group.

These websites are bullshit in the sense of philosopher Harry Frankfurt: it is irrelevant to their purpose whether Adderall really causes plantar fasciitis or not. They make their money from the question, not from the answer.

 

(via Keith Ng)

January 19, 2016

Rebooting your immune system?

OneNews had a strange-looking story about multiple sclerosis tonight, with lots of footage of one British guy who’d got much better after treatment, and some mentions of an ongoing trial. With the trial still going on, it wasn’t clear why there was publicity now, or why it mostly involved just one patient.

I Google these things so you don’t have to.

So. It turns out there was a new research paper behind the publicity. There is an international trial of immune stem cell transplant for multiple sclerosis, which plans to follow patients for five years after treatment. The research paper describes what happened for the first three years.

As the OneNews story says, there has been a theory for a long time that if you wipe out someone’s immune system and start over again, the new version wouldn’t attack the nervous system and the disease would be cured. The problem was two-fold. First, wiping out someone’s immune system is an extraordinarily drastic treatment — you give a lethal dose of chemotherapy, and then rescue the patient with a transplanted immune system. Second, it didn’t work reliably.

The researcher behind the current trial believes that the treatment would work reliably if it was done earlier — during one of the characteristic remissions in disease progress, rather than after all else fails. This trial involves 25 patients, and so far the results are reasonably positive, but three years is really to soon to tell whether the benefits are worth the treatment. Even with full follow-up of this uncontrolled study it probably won’t be clear exactly who the treatment is worthwhile for.

Why the one British guy? Well,

The BBC’s Panorama programme was given exclusive access to several patients who have undergone the stem cell transplant.

The news story is clipped from a more in-depth current-affairs programme. That BBC link also shows a slightly worrying paranoid attitude from the lead researcher

He said: “There has been resistance to this in the pharma and academic world. This is not a technology you can patent and we have achieved this without industry backing.”

That might explain pharma, but there’s no real reason for the lack of patents to be a problem for academics. It’s more likely that doctors are reluctant to recommend ultra-high-dose chemotherapy without more concrete evidence. After all, it was supposed to work for breast cancer and didn’t, and it was theorised to work for HIV and doesn’t seem to. And at least in the past it didn’t work reliably for multiple sclerosis.

All in all, I think the OneNews story was too one-sided given the interim nature of the data and lack of availability of the treatment.  It could also have said a bit more about how nasty the treatment is.  I can see it being fine as part of a story in a current affairs programme such as Panorama, but as TV news I think it went too far.

January 18, 2016

Supplement pushing

The Herald has a Daily Mail story about vitamin D for making you generally feel better. It’s not so long ago that the NZ media had a lot of less supportive coverage on vitamin D — Ian Reid, Mark Bolland, and Andrew Grey won the Prime Minister’s Science Prize last year for their work showing that calcium and vitamin D aren’t all they’re cracked up to be.

The story does have some new evidence.

In the study, by a medical team in Edinburgh, volunteers were asked to cycle for 20 minutes. They were then given either a placebo or vitamin D and, two weeks later, were asked to cycle for 20 minutes again.