Monday, June 25, 2007

Warning on drugs to cut post-surgical heart attacks

The journal article is here

DOCTORS are routinely giving drugs to patients in the belief they reduce post-surgical heart attacks when there is little or no evidence that they do any good - and in fact can cause significant harm. Tens of thousands of surgery patients every year in Australia alone are given beta-blockers, which slow the heartbeat, and cholesterol-lowering drugs called statins, just before or after non-cardiac surgery.

About 100 million patients are given the drugs each year worldwide, in the belief they reduce cardiac complications such as heart attack that affect between 0.5 and 1 per cent of patients. But an editorial by Australian experts published in the British Medical Journal says the basis for this practice is flawed and no patient should be given the drugs for this purpose.

Co-author Stephen Bolsin, director of anaesthesia at Victoria's Geelong Hospital and associate professor of patient safety, said the most recent and reliable studies suggested that contrary to earlier beliefs, the drugs had no effect on reducing complications. But patients were still exposed to their side-effects, which in the case of beta-blockers could include causing blood pressure to plunge dangerously, or the heartbeat to slow too much.

Statins are associated with liver and muscle toxicity. While Associate Professor Bolsin said these effects were rare when used after surgery, these drugs were more expensive than beta-blockers and cost health systems vast amounts for no patient benefit. "We suggest that patients already receiving beta-blockers or statins before surgery should continue with treatment," Associate Professor Bolsin wrote in the editorial.


Military suicide hoax

By Steven Milloy

Researchers and the media did their best this week to scare military personnel and their families with the widely reported headline, "Military Service Doubles Suicide risk". "Male veterans are twice as likely as their civilian counterparts to die by suicide," Portland State University professor Mark Kaplan told the Atlanta Journal Constitution. "We don't know why. But this finding may foreshadow what is going to come with the current cohort of military personnel who have served in Afghanistan and Iraq," he added.

Published in the Journal of Epidemiology and Community Health (July 2007), Kaplan's study consisted of 320,890 men who were followed for 12 years. As it is a statistical correlation study - rather than an investigation into whether an actual cause-and-effect relationship exists between military service and suicide - I naturally was skeptical. From the very beginning, the study didn't disappoint me.

The study summary stated that the veterans' suicide rate was 2.04 times that of non-veterans. When I read the study to see how the 2.04 figure was derived, I found no explanation. Mysteriously, the 2.04 figure did not even appear in the study itself - that's pretty unusual. I did, however, find a bar graph in the study that presented 2.13 as the difference in suicide rate between veterans and non-veterans.

You might think that this solved the mystery. A typographical or editorial foul-up must have inadvertently led to the 2.04-figure, rather than the 2.13 figure, being spotlighted in the study summary, right? We'll get to that later. In the meantime, my discovery of the 2.13-figure only deepened the mystery. Kaplan wrote in his study that the 2.13-figure represented the difference in suicide rates between veterans and non-veterans after statistical adjustment to account for other potential risk factors for suicide, including age, marital status, living arrangement, race, education, family income, employment status, geographic region, interval since last visit to a doctor, self-rated health and body mass index.

This list seemed impressively comprehensive and ostensibly strengthened the case for his claimed result - until, that is, I discovered that a key potential suicide risk factor apparently was omitted from his statistical adjustment. There's a table in Kaplan's study in which he presents the difference in veteran suicide rates by individual risk factors, including age, race, marital status, living arrangement, education, employment status, region of residence, urban/rural locality, self-rated health, body mass index, psychiatric conditions and activity limitation.

With the exception of race, education and activity limitation, none of these risk factors were statistically significantly associated with increased suicide rates. But since race, education and activity limitation were associated with increased suicide risk, all three should have been among the potential risk factors Kaplan considered when he did his statistical adjustments to produce the 2.13-figure. If you compare the above-mentioned lists of suicide risk factors, however, you'll note that while activity limitation was identified as a significant risk factor for suicide, it apparently was not included in the statistical adjustment that produced the 2.13-figure. And of the three statistically significant risk factors for suicide, activity limitation was by far the greatest - veterans with activity limitations had a 4.44 times greater rate of suicide than veterans with no activity limitations, as compared to race (3.23) and education (2.67).

Is the omission of the activity limitation factor another study typo? Was it inadvertently omitted from the statistical adjustment? Or was it omitted from the analysis because it would produce a non-result that rendered the study non-publishable and non-newsworthy? It certainly cannot be said that Kaplan was ignorant of the significance of the activity limitation risk factor. "According to Kaplan, the risk of suicide was highest among men whose activities were limited by health problems," reported the Atlanta Journal-Constitution.

Kaplan also published a study earlier this year entitled, "Physical illness, functional limitations and suicide risk: A population-based study" in the American Journal of Orthopsychiatry (Jan. 2007) in which he stated, "After controlling for potential [confounding risk factors], functional limitations were shown to be a significant predictor of suicide."

When I contacted Kaplan about these issues, he immediately acknowledged that the 2.04-figure was a typo and that the 2.13-figure was correct. Interestingly, he also provided me with a dubious error bar for the 2.13 figure. When I asked him about that, another acknowledgment of error was made. These may seem like small errors, but they certainly build no confidence.

As to the crucial omission of activity limitation as a risk factor, Kaplan deferred responding, writing that he needed to consult with one of his statistician co-authors. As of the time of this column, I had not heard back from Kaplan on that point. But you might think that a lead study author who gave many media interviews this week would be readily familiar with such a key component of his analysis. Of all the researchers I've interviewed over the years about their results, none has ever failed to immediately provide an answer to such a basic question.

I don't know whether Kaplan ultimately will produce a satisfactory explanation for the activity limitation omission - the study's remaining mystery. In some ways it doesn't matter. The study's other shortcomings - particularly that veteran suicide rates weren't higher across the vast majority of demographic groups examined, which indicates that military service itself isn't a causative factor in suicide - are alone enough to debunk it and the scary headlines it spawned.

But the wide reporting of a paper with such major and easily discoverable problems - as well as Kaplan's questionable effort to foment concern about suicide risk among veterans of Afghanistan and Iraq - reflects poorly on him and his co-authors, the publishing journal and the media.



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.


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