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How we know what we know

Posted in Denialism, Medicine by Skepdude on August 19, 2008

CLICK HERE TO GO TO THE ORIGINAL ENTRY AT THE “DENIALISM” BLOG.

Over the last few decades, the nature of medical knowledge has changed significantly. Before the revolution in evidence-based medicine, clinical medicine was practiced as more of an art (in the “artisan” sense). Individuals were treated empirically with a strong knowledge of medical biology, and the guidance of “The Giants”, or particularly skilled and respected practitioners. While the opinions of skilled practitioners is still valued, EBM adds a new value—one of “show me the evidence”.

Evidence-based medicine refers to the entire practice of gathering and applying medical knowledge. This includes evaluating diagnostic tests (e.g. how well does an CT scan diagnose pulmonary embolism?) and evaluating treatments (e.g. which anticoagulant is most effective, which one is safer, how long should you treat, etc.) There will always be some questions that are untestable, and some for which no testing is needed, and practices for which evidence is sketchy.

In corresponding with a friend recently, I started thinking about how we look at the quality of medical evidence, and how we can communicate this to the lay public.

Let’s take, for example, cholesterol.

It has been found over the years that there is a strong association between elevated cholesterol and coronary artery disease. Through many studies, it was found that LDL cholesterol is a useful marker of cardiac risk due to elevated cholesterol. Finally, it was found that lowering LDL cholesterol, especially with statin drugs, dramatically reduces heart disease risk and mortality.

That’s the facts. But what are they based on? How strong is the evidence?

Evidence-based medicine has many ways of grading quality of evidence. The primary reference for cholesterol treatment in the U.S. is the National Cholesterol Education Program’s Adult Treatment Panel III (NCEP and ATP III).

Before the report gets to any recommendations, it presents a table explaining how evidence used in the report is graded. First is the type of evidence (from randomized controlled trials down to clinical experience) then is the quality (from “very strong evidence” to “strong trend”).

For example, the ATP gives the following recommendation (among many):

Evidence statements: Secondary prevention trials demonstrate that reduction of LDL-cholesterol levels significantly reduces risk for recurrent major coronary events in persons with established CHD (A1).

That “A1” at the end gives an idea what kind of evidence we’re working with. In this case the statement is based on RCTs and there very strong evidence to support it.

Evidence-based medicine is about evidence. Sometimes that evidence is quite good, sometimes it isn’t: the quality of evidence is something we take into consideration when treating patients.

This is in stark contrast to so-called alternative medicine. Alternative medicine never discusses quality of evidence. The quality is usually, however, quite poor, relying on patient and physician anecdotes, uncontrolled “trials”, and fantasy.

Making use of EBM doesn’t have to be difficult. You don’t have to be able to interpret every chi-squared analysis, you don’t have to calculate every number needed to treat. You just have to be able to read the basic literature in your field, look up recommendations, and know how strong they are.

Anyone practitioner who ignores evidence-based medicine is not practicing the best of modern medicine. Anyone who treats disease without understanding the difference between evidence-based practice and non-evidence-based practice should hand you a Quack Miranda Warning when you walk in the door.

CLICK HERE TO GO TO THE ORIGINAL ENTRY AT THE “DENIALISM” BLOG.

Conscientious objector or deserter?

Posted in Denialism, Medicine by Skepdude on August 4, 2008

CLICK HERE TO GO TO THE ORIGINAL ENTRY AT “DENIALISM”

The discussion we’ve had since Friday regarding the Bush administration’s latest foray into theocracy brought up some interesting points. We discussed implications of the draft regulations including likely limitations on access to safe and effective birth control. But there is another issue here that disturbs me greatly.

Last week we talked a little bit about medical ethics. I’m not an Ethicist (Mike! Are you reading?), but I am a “practical ethicist”, as are all health care providers. How do ethics inform the discussion of what care we can or cannot provide?

First, let’s take the gloves off for a moment. What is a “pharmacist”?

A pharmacist is a trained professional with an expert knowledge of medications. In the retail setting, their primary role is to dispense medications, but their actual role is far greater. Pharmacists check patients’ records for drug interactions, counsel patients on how to properly store and take medications, and communicate with doctors regarding potential problems with prescriptions. Pharmacists are not, in most settings, the patient’s clinician, and do not have the same type of (ethical) relationship to their customers as doctors do with their patients. They are, at the simplest level, technicians and scientists who help maintain the safety and integrity of patients’ medications. It is a great responsibility—one small mistake on the part of a pharmacist can kill, and one small mistake caught by a pharmacist can save a life.

When a pharmacist receives a prescription from a physician that they believe may pose a threat to a patient, they call the doctor. For example, if I were to write a prescription for levothyroxine 125mg daily, the pharmacist would call me up to see if I meant micrograms rather than milligrams (125 mg is a helluva lot of this drug). If I tell the pharmacist to shut up and dispense the damned drug as written, they might refuse to pending further research, discussion, etc. This often happens with opiates. I may prescribe a cancer patient a very large dose of morphine and the pharmacist will call me to confirm. I’ll explain that they have been on this dose and tolerated it well, and the pharmacist will likely be satisfied that I know what I’m doing.

A pharmacist that receives a properly written prescription for a medication that any reasonable doctor would consider safe may not ethically refuse to fill it. The doctor and patient are the ones who make the decision on what meds are proper. In this case the pharmacists only remaining job, after checking for allergies and drug interactions, is to fill the legal prescription. If they don’t wish to do that, they should be fired, just as the check-out clerk would be fired for refusing to ring up a candy bar (and no, it doesn’t matter how fat the customer is). It has come up frequently that pharmacists sometimes refuse to fill birth control pills. This is unconscionable. The doctor and patient have a clinical relationship; the pharmacist in this instance is an intermediary, and could theoretically be replace by a sophisticated vending machine. Hmmm….

__________

The relationship between physician and patient is a bit more complicated. There is an asymmetry in the power relationship—anything the doctor says and does is potentially coercive. The doctor and the patient both count on this asymmetry—a patient goes to the doctor for advice, a doctor hopes their position of authority will help persuade the patient to do what is necessary (more on this issue of autonomy vs. paternalism here).

If a doctor tells a patient that smoking is dangerous, the patient is likely to believe them and will treat the words differently than if they had come from someone else. The same goes for a doctor’s opinions. If I tell my patient that I love Obama and that voting for McCain would ruin the American health care system, I’m probably using my influence in a bit of a shady manner. If a young woman comes to me wishing to terminate a pregnancy, and I tell her it is tantamount to killing a child, it means something very different to her than if she sees it on a billboard. If I oppose abortion, and feel I wish to be a “conscientious objector”, to share that with the patient is no longer an act of conscience, but an act of coercion. It is a desertion of my duty as a physician. I have patients who are Jehovah’s Witnesses. I give them very detailed information about the medical (not moral) consequences of their beliefs, but I stop there.

Doctors are activists—activists for the rights and needs of our patients, to which we subsume our own values to a great extent. This is one of the great challenges of medicine, and if you’re not up to the task, it’s time to get out.

CLICK HERE TO GO TO THE ORIGINAL ENTRY AT “DENIALISM”