Friday, December 21, 2007

Evidence-Based Medicine

There is a rather confused article below. It starts out saying "Proponents of EBM assume it will improve the quality of health care by basing medical decisions primarily on statistically valid clinical trials" and then says "EBM, by contrast, relies primarily on epidemiological data". Which is it? Both cannot be true. I would deplore the latter and support the former. The article is really just another example of the old cry by clinicians that they "just know".

A new buzzword entered the medical lexicon in 1992 when the Evidence-Based Medicine Working Group published one of the first articles on the phenomenon in the Journal of the American Medical Association (JAMA). In the years since, the role that evidence-based medicine (EBM) plays in medical care has increased exponentially. Some now question whether it should play such a prominent role.

"[EBM is not] medicine based on evidence, but the equivalent in the field of medicine of a cult with its unique dogma, high priest ... and fervent disciples," says Dr. John Service, editor-in-chief of Endocrine Practice. Indeed, if a doctor questions EBM today, it seems he or she runs the risk of being branded an infidel or heretic, or worse.

Proponents of EBM assume it will improve the quality of health care by basing medical decisions primarily on statistically valid clinical trials; therefore, information gained from randomized clinical trials (RCT) preempts information from all other sources. Yet, isn't it ironic that a review of the literature by this author and others turns up no evidence as defined by EBM to validate this assumption?

"The failure to conduct a randomized controlled trial, the recognized best form of evidence according to EBM, and reliance on expert opinion, namely theirs (the worst form of evidence according to them), hoist EBM by its own petard," notes Service. EBM purports to provide "statistical proof" when in fact what it provides is "statistical data." Data does not necessarily equate to proof. Data is open to interpretation, which can change over time or vary depending upon one's perspective.

Dr. George Spaeth makes this point in evaluating the Ocular Hypertension Treatment Study, which involved more than 1,000 people who had increased intraocular pressure but no optic nerve damage or visual field loss. Only 5 percent of those treated went on to develop visual field loss, whereas 10 percent of those not treated did.

This data can be used to argue either for or against treatment, Spaeth notes, depending on one's interpretation and incentives. The treating physician could argue that instituting early treatment would reduce visual field loss from glaucoma by 50 percent. Yet, a third-party payer with financial incentive could just as easily argue against treatment, noting that the overwhelming majority of patients with elevated intraocular pressure do not get worse, even when not treated. Consider the evidence. Who is right? They both are.

Is there, indeed, a best practice regarding the approach to elevated intraocular pressure? If so, how should the algorithm be constructed? Who should have the ultimate discretion in making that decision? Should it be the treating physician, with the best interest of the individual patient in mind? Or a third party with the best interest of the bottom line in mind? Clinicians now fear medical malpractice suits if they do not follow EBM guidelines in treating patients. But as one resident recently asked me, which guidelines do you follow? Even guidelines about the same disease can vary substantially, depending upon which professional organization promulgated them. What's more, by following them, don't we freeze medical practice in time? How is progress to be made in health care if we are forced to walk in lockstep with algorithms promulgated last year or the year before?

It is not the epidemiological data of EBM that I question, but rather the manner in which it is used to displace clinical judgment. The physician has taken the history, performed the physical, reviewed the labs, and discussed the illness with the patient and family. He knows the patient's wishes, desires, and values. All this critical information must be considered when treating patients.

EBM, by contrast, relies primarily on epidemiological data, which it uses in a way that preempts all other information collected by the treating physician. In fact, non-quantifiable information such as the patient's values and the physician's clinical experience are not even taken into account in EBM.

It is absurd to think that a third party, operating at a distance in time and space from the patient being treated, is able to make a better medical decision than the treating physician and therefore should be allowed to preempt the treating physician's decisions. Entire medical conferences are devoted to EBM, focusing on the statistical purity of the studies. Statisticians are hired to participate in such conferences. Meanwhile, the clinical question for which evidence was being sought takes a back seat. "The result is form taking precedence over substance," says Service. In the process, it is often forgotten that a group's responses, as an aggregate, can be quite different from an individual's response to a specific therapy. Patients are individuals, not groups. When one treatment is shown to be better than another on a population basis, this does not necessarily mean that it is the best treatment for the patient.

The decisions whether and how to treat a disease ultimately lie with patients, who makes these decisions with their doctors' help. It's a value judgment, and there is no way to measure value. It is not quantifiable in inches, pounds, or miles per hour. The ultimate discretion regarding how information from multiple sources (including EBM, prior clinical experience, and the patient's unique circumstances, wishes, and desires) are integrated for treating individuals should be in the physician's hands. Since he has the ultimate responsibility for the patient's care, he should have the ultimate discretion


When fatness becomes madness

THE world has officially gone mad. I thought we had reached that stage when Lisa Marie Presley married Michael Jackson, but last week we went a step beyond. Someone in a position of authority recommended that children as young as four be weighed on arrival at kindergarten to curb the obesity "crisis". Call me old-fashioned, but further marginalising fat kids at an age when their peers display an apparently innate cruelty is not a good idea. What will we do with those who do not meet the arbitrary body mass index? Send them to kiddie fat camps?

A relative used to tell my curvaceous cousins that the doors would have to be widened if they did not stop putting on weight - and this to prepubescent girls. We live in a PC world now that recoils from such offensive language, but I'd rather that kind of jaw-dropping candour to the subterfuge people resort to these days. My relative's brand of mean-spirited taunts now hides behind "concern" for our "health", but this is not about health - it's about appearance. If the issue is health, why are we not concerned about those skinny people who eat dreadfully? Everyone knows this person - rake thin, a McDonald's bag always in hand, able to inhale a pack of Tim-Tams at one sitting. These lucky folk have their freak metabolisms to thank, which brings me to my next point.

The word hereditary rarely crops up in the obesity debate, despite overwhelming evidence that any health condition and body type is 95 per cent hereditary. As a society we want to assign blame. If you are fat it is your fault: you are slovenly, lazy, undisciplined. A dietitian will dispute this assertion, but society isn't having it. It has gone so far that a television show recently polled viewers on whether Santa was too fat.

A few years ago I had a gig as an in-store Santa at a shopping mall. For 14 days I sat for four hours a day in my chair, facing a US fast food chain outlet that sells ice-cream and mystery-meat hot dogs. I got to see who, if anybody, typified the average customer there. Nine out of 10 were thin. Where were all the "undisciplined" fatties one would expect? As they have been hounded since birth about their weight, they made rare, sheepish appearances.

Did I crack and have an ice-cream after watching others eat for 14 days in a row? Of course not. I was watching my weight.



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].

9). And how odd it is that we never hear of the huge American study which showed that women who eat lots of veggies have an INCREASED risk of stomach cancer? So the official recommendation to eat five lots of veggies every day might just be creating lots of cancer for the future! It's as plausible (i.e. not very) as all the other dietary "wisdom" we read about fat etc.

10). And will "this generation of Western children be the first in history to lead shorter lives than their parents did"? This is another anti-fat scare that emanates from a much-cited editorial in a prominent medical journal that said so. Yet this editorial offered no statistical basis for its opinion -- an opinion that flies directly in the face of the available evidence.

Even statistical correlations far stronger than anything found in medical research may disappear if more data is used. A remarkable example from Sociology:
"The modern literature on hate crimes began with a remarkable 1933 book by Arthur Raper titled The Tragedy of Lynching. Raper assembled data on the number of lynchings each year in the South and on the price of an acre's yield of cotton. He calculated the correlation coefficient between the two series at -0.532. In other words, when the economy was doing well, the number of lynchings was lower.... In 2001, Donald Green, Laurence McFalls, and Jennifer Smith published a paper that demolished the alleged connection between economic conditions and lynchings in Raper's data. Raper had the misfortune of stopping his analysis in 1929. After the Great Depression hit, the price of cotton plummeted and economic conditions deteriorated, yet lynchings continued to fall. The correlation disappeared altogether when more years of data were added."
So we must be sure to base our conclusions on ALL the data. But in medical research, data selectivity and the "overlooking" of discordant research findings is epidemic.


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