09 April 2011

Unhealthful News 99 - LATimes on CT scans and coffee

The past day saw two great bits of unhealthful news in the Los Angeles Times.  The first was what appears to be a syndicated column, in which the author warns readers that hospitals' aggressive use of CT scans, particularly for situations of uncertain urgency like head injuries, causes some risk from the radiation.  The column focused on children, who it is suggested get a larger does of radiation than adults, though it is not entirely clear what the basis for that claim is.  The hook for the report was a study in the journal Radiology which reported the completely unsurprising result that CT scans of kids in the emergency room increased markedly during the period 1995 to 2008, a period during which the equipment became nearly universally available and fairly cheap.

The basic message is a good one, though the columns author, Nicole Brochu, did not actually manage to deliver it:  When a test (or treatment, or whatever) causes a risk, that raises the bar for when we decide it is best to do it.  Instead of making that clear, though, the author writes for several hundred words without ever saying anything even that definitive.  In fairness, the general message is that parents should ask "is this really necessary" type questions in appropriate situations.  But there is no information in the column about which circumstances might be borderline enough to warrant doubts, as opposed to those where the costs clearly outweigh the benefits.  So this just falls into the popular category of someone saying "it is safe and worthwhile" and someone else saying "we should be wary", with no on addressing the tough questions reader actually learning anything. 

Of course, identifying the gray area is tough, so maybe we should let Brochu off the hook.  It is one thing to recognize that there is a level of risk where a physician might blithely recommend a test that (probabilistically) causes more harm than good – that is simple general science knowledge.  It is another to be able say something about where this range is.  Why, you would have to be qualified to, say, write a column about the subject matter before you knew enough to offer such advice.  Oh, wait.

The second article dealt with coffee, and though it did not contain anything new, I just cannot resist the topic.  The story offered a selective review of research on the topic of coffee consumption and cardiovascular disease (stroke and heart attack) and claimed that recent research suggests the net effect might be beneficial.  The research method employed in the article is rather weak, but the conclusion seems defensible based on a more systematic review.  It was generally assumed that any stimulant would increase CVD risk, at least a bit.  There is also the attitude noted by a medic who was interviewed (it is difficult to tell what tone was intended – whether he was trying to criticize the conventional wisdom or explain that it had a good basis – since the reporter gave no further context):
Coffee is fun and it tastes good, so people assumed for many years that it would be bad for you.
This possible beneficial effect of coffee makes you wonder if perhaps consuming tobacco might have CVD benefits (so long as you do not smoke it, of course – that is terrible for CVD and other risk).  Again, we have tended to assume that the effect would be negative, but there is less reason to continue to assume this in the face of the surprising  conclusions about coffee.  They are rather different plants and plant parts, so there is little justification for just assuming that tobacco leaves would work like coffee seeds.  But we should generalize the conclusion "we do not know everything about how stimulant plant exposures affect CVD that we might" and question the assumption a bit more.

The last word in the article was given to the same medic again, suggesting that perhaps the previous quote was not meant to be professionally self-deprecating, but was what he thinks passes for scientific reasoning.  He claimed that to sort out the uncertainty and controversy about whether coffee really was preventing stroke and other other diseases, we:
would need to randomly select people to drink either a lot of coffee or a little coffee, and then researchers would have to closely monitor their coffee intake and health for decades.  And that, says [he], would be "very difficult, and really expensive."
Which is why we still do not know that smoking causes cancer.  Oh, wait.

Strangely, he understates the case against doing such a controlled trial.   manned mission to Mars would be "very difficult and really expensive".  A randomized trial of a lifetime of coffee use would be impossible for several reasons.  But you can always count on a physician to make a naive comment about scientific inference if you want one.  Another physician who was quoted rounded out the stereotypes for bad health advice from that quarter, saying that even if coffee offered a CVD benefit, non-users should not start consuming it because it is not 100% benign.  I wonder if he uses the same reasoning about statin drugs?

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