TCS Daily


Medical "Truths"

By Sydney Smith - March 23, 2004 12:00 AM

A hundred years ago it was accepted as scientific fact that emphysema was an occupational hazard for glass blowers and wind instrument players. Emphysematous lungs are large, limp, and less elastic than normal lungs. Glass blowers and horn blowers suck air in and out of their lungs all day. It only made sense that their lungs would look and behave like a balloon that had been blown up and deflated time and again. It was one theory that was considered well grounded and rational by the standards of its day. But then, someone actually measured the incidence of emphysema in glass blowers and horn blowers and found that the condition was not rampant, but rather rare. Medical science marched on, leaving yet another "fact" in its wake.

And medical science has continued to march on, or so we like to think. Discriminating doctors of the early twenty-first century, unlike the doctors of the early twentieth, pride themselves on practicing "evidence based medicine." Unless there's a paper and statistics to back up a theory, we don't put it into practice. We like to think of medicine as a hard science, as dependent on the observable and quantifiable as chemistry, or some branches of physics. But, the truth is, in many respects medical science has devolved into a science as soft as economics or sociology.

Take for example, the now infamous MMR and autism study that the prestigious Lancet published in 1998. Its purpose was to investigate the connection, if any, between inflammatory bowel disease and autism. It was study of only twelve children in England who had both disorders. In the course of the study, the researchers noted that eight of the twelve children's parents thought that the MMR vaccine was related to their children's illnesses. That was the extent of the connection. This is not so unusual, since the MMR vaccine is given between the twelve and fifteen months of age, the same age range in which autism first becomes recognizable. And, although the researchers were careful in their concluding remarks to say that neither they, nor anyone else to date, found any evidence linking the MMR vaccine to autism, they didn't refrain from expounding on a hypothetical connection between the two in their discussion.

There's nothing wrong with putting forth a hypothesis. That's what science is about, coming up with and disproving hypotheses. But not all hypotheses are created equal, and this one was based on particularly shoddy science -- a very small study, and the confusion of association with causation. Yet, for some reason The Lancet found it worthy of publication, well aware of the potentially devastating effects its poorly thought out conclusions could have on public health. At the time of publication, the article was accompanied by a prescient guest editorial from an official at the CDC that warned that "passion would conquer reason and the facts" if the study's conclusions were taken at face value by the media and the public. And that is just what happened. Blessed with the imprimatur of a world renowned medical journal, and a subject enticing to the media, the lead researcher was treated to a press conference at which he suggested that parents should avoid the MMR vaccine. MMR vaccine rates in Great Britain, where the story got much play, plummeted, and the incidence of measles rose. Within two years of the study's publication, there was a measles outbreak in Dublin that killed two children and hospitalized hundreds more.

And, although most physicians were capable of recognizing the poor science behind the theory, the editors of the Lancet apparently were not. They still are not able to recognize it. They've issued a partial retraction, not because the paper's conclusions were poorly thought out, but because the lead investigator had undeclared financial ties to a group seeking legal action against the vaccine's manufacturer. Presumably, bad science is only bad in the eyes of the Lancet if it's funded by the wrong interest group.

Unfortunately, this fondness for soft science is not unique to the British medical establishment. This month the equally prestigious Journal of the American Medical Association published a paper deceptively titled Actual Causes of Death, 2000 that claimed that obesity was gaining on tobacco as the number one cause of death in the United States. Except that the paper's objective wasn't to quantify actual causes of death, it was to attribute the risk of death to various behaviors -- behaviors that were preselected by the researchers.

And so, after a little statistical manipulation, the top ten actual causes of death -- which are diseases and accidents -- morph into a list worthy of the seven deadly sins: gluttony, sloth, and lust. Presumably, by this logic, if we all lived puritanical lives we could come pretty close to eliminating death all together. It is as much a confusion of association with causation as the MMR and autism study was. But, all the same, it's being used as an impetus for a series of government programs to change our behavior, all at taxpayer expense.

These are but two of the most recent and glaring examples of just how soft medical science has become, or perhaps remained. There's no shortage of marginal hypotheses that appear in the medical literature and are passed on to the lay press as solid fact. That's why one day hormone replacement therapy is good for you and the next it's bad. Why one day fish is a health food, and the next it's a toxin. We may have better technology, better drugs, and a better understanding of many disease processes than our forefathers did a hundred years ago, but we're no more sophisticated than they were in sifting the bad science from the good.

Sydney Smith is a family physician who has been in private practice since 1991. She is board certified by the American Board of Family Practice, and is a Fellow of the American Academy of Family Practice. She is the publisher of MedPundit. She recently wrote for TCS about the Terry Schiavo case.


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