Posts filed under Medical news (341)

It’s not often that you see a special interest group make a claim about the economic impact of their chosen problem and think “I never imagined it could be so small”.

Today is, apparently, World Sleep Day, and we have a problem

A quarter of New Zealanders have a chronic sleep problem, according to the World Association of Sleep Medicine.

Studies by the World Association of Sleep Medicine show sleep disorders cost New Zealand at least 40 million dollars a year in lost productivity

A quarter of (working-age) New Zealanders is a bit under a million people, so that’s an average of about a buck a week, or about five minutes per sufferer per week at minimum wage.   Can lack of sleep really be that unimportant economically, or has someone dropped a decimal place somewhere?

The Herald did a good job itself in providing statistics to put today’s front-page story in context

BREAST CANCER

2700 number of new cases in 2008

624 number of deaths in 2008

8: number of women who had something unspecified wrong with their diagnosis, for reasons we don’t give, having unknown impact on their future health, in circumstances that are still being investigated but might not be exciting enough for the front page if we wait for the facts.

The Heart Foundation is calling for approval of a new drug, ivabradine (for subsidy — it’s already approved for prescription).  The report in Stuff, unfortunately, puts in a bunch of numbers of varying relevance.

We are told the pill costs “as little as $3 a day” and that “Up to 160,000 people” in New Zealand have heart disease.  If ivabradine was actually useful in all those 160,000 people, the total cost would be $175 million per year, or about a quarter of Pharmac’s budget.   And you would know about it already.

The randomized trials of ivabradine, which do look very promising, are in people with one specific type of heart failure.  Heart failure is a particularly nasty form of chronic heart disease where the heart can’t pump enough blood to supply oxygen to the body.  Slowing down the heart rate helps — for centuries, foxglove extract (digitalis) was used, and the introduction of standardised versions of digitalis in 1785 is regarded as the start of modern therapeutics.  Fortunately, heart failure is a relatively small part of heart disease in the population.   There’s about 10,000 hospitalisations per year for heart failure, but that’s not 10,000 different people.  A 2005 paper found 8000 deaths over 9 years, or about 900 per year.   Not all of these will be the specific type of heart failure where ivabradine works.

If ivabradine works as well in practice as in the trials, and there don’t turn out to be any nasty side-effects, the Heart Foundation could be right — it could potentially prevent (actually, postpone for a bit) hundreds of deaths per year in NZ.   But the 160,000 people with heart disease or the one death every 90 minutes from all types of heart disease are not relevant to this much more specialised medical question.

News outlets around the world and locally are reporting on a study that found loud music made alcohol taste sweeter.  The research participants drank various concentrations of cranberry & vodka while listening to nothing,  loud annoying music, a news track that they had to repeat back, or both the music and the news.

People who listened to the music rated the drinks as sweeter.  The researchers suggest this explains why people drink more in clubs.  I think they’re missing an important point.  The sweetness of alcoholic drinks is under the control of the manufacturer and the drinker, and there’s no reason to think that people in quiet settings deliberately choose drinks that are less sweet than they would prefer.  If the noise effect is strong enough to be meaningful in practice, it should just mean that people choose less sweet drinks when it’s loud and sweeter ones when it’s quiet — the same way that people allegedly drink more tomato juice on aeroplanes because taste sensations are different at altitude.

The researchers also found that the combination of the music and the news task “was accompanied by increased negative mood”, so if you need to take dictation, choose a bar that plays country and western, not hardcore.

The Herald headline is “Icecream cravings like cocaine: study”, and it’s another paper from our friends at the American Journal of Clinical Nutrition, but this time filtered through the British press.

Co-author of the study, Dr Kyle Burger, from the Oregon Research Institute, told The Daily Telegraph overeating high fat or high sugar foods appeared to change the way the brain responded to the food.

That’s not quite what the paper said he found.  The study looked at brain activity in people drinking a milkshake compared to a tasteless drink, and found that the milkshake effect was smaller in people who had eaten icecream frequently in past weeks.  But it wasn’t smaller in people who had eaten cookies, chocolate, hamburgers, cake, or chips, and there wasn’t any relationship to total dietary fat and sugar.   So, in fact, the study found that overeating high fat or high sugar foods did not appear to change the way the brain responded to the food.  As far as I can tell (and, unlike you, I can get the whole paper), the study does not report at all on the relationship between craving for icecream and the brain activity measurements.

So. The study found that brain response to a milkshake was weaker in people who eat a lot of icecream, but was unrelated to other high-fat or high-sugar foods, and that people who have cravings for icecream eat more icecream than people who don’t have cravings for it.

Stuff has a story on robot-assisted surgeries, claiming

Patients who have robot-assisted surgeries on their kidneys or prostate have shorter hospital stays and a lower risk of having a blood transfusion or dying – but the bill is significantly higher, a study found.

That’s not quite what the study found.  The abstract says

While robotic assisted and laparoscopic surgery are associated with fewer deaths, complications, transfusions and shorter length of hospital stay compared to open surgery, robotic assisted laparoscopic surgery is more costly than laparoscopic and open surgery.

The researchers used the Nationwide Inpatient Sample, a random subset of US hospital admissions, to compare three approaches to prostate and kidney surgery: laparoscopic (‘keyhole’) surgery by hand, robot-assisted laparoscopic surgery, and open (non-keyhole) surgery.  They found that laparoscopic surgery, whether robot-assisted or not, was safer than open surgery, but they didn’t report an advantage of robot over non-robot keyhole surgery, just an increase in cost.

Now, you might well be muttering about causation and correlation, and asking “How do we know the open surgeries weren’t just more difficult cases?” If you aren’t, then you can start now and I’ll let you pretend you were doing it all along.  Since surgeon experience makes a big difference, we should also worry whether it’s the most experienced surgeons who get the expensive and shiny new robots.

The researchers did try to cope with this problem using a technique called propensity scores.  Essentially, they tried to classify patients according to how likely they were to have an open surgery vs manual laparoscopic surgery vs a robot surgery, and match the patients so comparisons were done only between similar cases.  However, the researchers did say in the main body of the paper  “Results from unadjusted and propensity adjusted analyses were largely similar”, ie, the attempt to remove bias didn’t actually remove any bias.  The optimistic view is that this means there wasn’t any bias; the pessimistic realistic view is that it means the adjustment probably failed.

Surgical robots have been a bit of a disappointment.  It’s not that they don’t work, but they were supposed to have huge and dramatic advantages (over and above “ooh, shiny”) and these huge advantages don’t seem to have materialized.

The American Journal of Clinical Nutrition missed an opportunity when they put a meta-analysis of randomized studies of chocolate in the March issue rather than the February issue, but that hasn’t stopped the media coverage.  Stuff has a headline asking “Is chocolate really heart-healthy?”  There’s a law of journalism that states any headline ending in a question mark can be answered by the word “No”, and Stuff does not disappoint us here.

The newspaper story is actually pretty good — very good by the standards of nutrition journalism.  There are four key points, and the story makes three of them clearly and alludes to the fourth (more…)

There were two stories on avoidable medical errors last night when I was watching the news.  The obvious one was on statistics from the District Health Boards on errors made in hospitals. These were up last year, though we don’t know whether it was better reporting or more errors.  On this topic, the best person to read is US surgeon Atul Gawande, especially his book The Checklist Manifesto.  As he points out, doctors do the wrong thing a lot more than they did a century ago, because there are so many more things they have to do right — medicine is getting more and more complicated.   It’s also helpful context to remember that avoidable errors in driving cause about 300 deaths and 6000 serious injuries per year in New Zealand.

The other story was on avoidable public health errors: the rate of infectious disease in New Zealand and its relationship to poverty and ethnicity. There are a lot of different diseases involved, but the most dramatic example is rheumatic fever.   Rheumatic fever is a nasty and almost completely preventable complication of  streptococcal throat infections, and in industrialized nations with modern healthcare systems it just shouldn’t be happening.   In the US, rheumatic fever is sufficiently obscure that it showed up in an episode of House, and even then it was just due to the patient not taking prescribed antibiotics properly.   There are major NZ initiatives to reduce rheumatic fever,  but this is the sort of medical statistic that should be in the news, because public awareness and public pressure on government is helpful in getting the problem fixed (rather than just getting it hidden, as is the risk with hospital errors).

Stuff is reporting on a new paper in the BMJ (or as Stuff calls it, only 24 years after the name change, the British Medical Journal) saying that smoking dope doubles your chance of  a serious or fatal car accident.  Regular readers of StatsChat posts on drug journalism will be pleasantly surprised to hear that this is actually what the research paper says, and that the researchers had moderately good evidence for this conclusion.

The paper compiled the results of previous studies, restricting their attention to studies that had a control group, and that measured  actual THC concentration in the blood, rather than the inactive metabolites that can be detected days later in blood or urine.   Some of the studies compared drivers in crashes to drivers not in crashes, others compared the driver responsible for the crash to other drivers involved in the crash.

The summary of the findings looking at various ways of breaking up the data is:

That’s a forest plot, with the dots showing the estimated risk ratio [technically odds ratio, but it doesn’t matter in this context] and the lines showing the 95% margin of uncertainty.   Though some of the lines include the null value 1.0 and others don’t, there’s pretty clear agreement across the analyses that cannabis increases crash risk, by a factor of two or so.

After getting it right so far, Stuff unfortunately went further and said “The research found cannabis significantly impaired the psychomotor response, or muscle activity linked to mental processes.”  That isn’t actually what they found. That’s in the Introduction section of the paper, because it’s telling us what was already known — dope makes you slower and clumsier.  The BMJ isn’t publishing research telling us that, any more than they publish conclusions on the spatial distribution of ursine excretory activities, or the religious affiliation of the Pope.

They finish up by saying “The Land Transport Amendment Act 2009 will be reviewed this year and police are investigating the possibility of introducing more effective roadside drug tests.” This paper doesn’t really lend much support to changes in current roadside drug tests, which have the advantage of testing for actual impairment and not being specific to a single drug.

There has been a lot of fuss recently in the West Island around a paper by Dr Alan Barclay on trends in sugar consumption and obesity.  When read as a reaction to a rather extreme US paper in the prominent journal Nature claiming ‘sugar is as toxic as alcohol‘ it is a reasonable piece of analysis, but it is being overinterpreted.

The New Zealand Science Media Centre (who are typically sensible and well-informed*) and their Australian counterparts have commentary on the ‘evil sugar’ paper from three experts, who agree that specific effects of sugar beyond its calorie content are not that strong, and, of course, that excess sugar consumption doesn’t directly hurt anyone but you: it doesn’t make you get into fights or crash cars.  On the other hand, there is the calorie content.

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