Friday, June 22, 2007

The art and science of medicine

A response

The following is a slightly expanded response I wrote in a comment thread regarding the "On evidence based medicine and the art of healing" post. It is interesting to dicuss the fallacious and not so fallacious claims (mostly the former). If any one has ideas of communicating how science works in a medical context, please feel free to comment.

''Evidence-based medicine doesn't rely on clinical insight, medical training or personal experience.''

On the contrary, EBM relies intimately on them. EBM is "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research." (Sackett D, 1996) The evidence, by itself, does not make a decision for you, but it can help support the patient care process. The full integration of these three components into clinical decisions enhances the opportunity for optimal clinical outcomes and quality of life.

"It is based on data from medical journal articles, epidemiology and economics, which relies on randomized clinical trials, which doesn't even require a medical education.”

Evidence-based medicine "converts the abstract exercise of reading and appraising the literature into the pragmatic process of using the literature to benefit individual patients while simultaneously expanding the clinician's knowledge base." (Bordley DR, 1997) You need that DVM or MD title to put it all together for your patient.

''Nonphysicians trained in social science, science or even public policy analysis, have judgement over medicine. Where doctors defined the "standard of care," now payers and purchasers of medical services redefine the standards for appropriate medical care, encouraging doctors to act in ways to promote their financial interest when they make medical decisions.''

Here you are comparing apples to oranges. First, the general body of science based information is gathered by a broad representation of professionals from the basic sciences (chemistry, biology, biochemistry, physiology…), research physicians, tenured faculty, practicing doctors to name some. It is from this body of evidence and understanding that medicine needs to rely.

On the other hand, I agree that there are big problems with third party intrusions, socio-political interests, big corporate lobbying pressures…that inhibit the medical profession- but this is not EBM. That these special interests twist and deform whatever they touch does not change the essence of EBM, science, and an honest and open pursuit of knowledge.

''When evidence from a clinical trial suggests that one therapy is superior to another, it can be used to change prevailing medical practice. The effects of this information requires that some medical specialties and medical suppliers lose income while others gain income. And sometimes evidence may be preliminary rather than well established so that their long-term effects are not known.''

This is part of the human condition and the knowledge gaining process- a science based perspective at least provides a self critical, self correcting mechanism to seek the best balance through time.

''Predictive "accuracy" is the chief criterion traditionally used to validate all diagnostic laboratory tests currently in use in cancer medicine.''

Not sure what you mean here. The specificity and sensitivity of diagnostic, prognostic, and therapeutic analysis will vary depending on what you are evaluating- this includes the history and discussion with the patient, examination, and so on- the whole picture helps dictate the interpretation and validity of whatever the modality in question is.

''The "establishment" itself (NCI) has stated on its official cancer information website on "state of the art" chemotherapy, it is unclear whether single-agent or combinations of drugs is preferable for first-line treatment. No data support the superiority of any particular regimen.''

You need to look at what type of neoplastic process you are dealing with before you can state anything about treatment approaches such as chemotherapy. A plethora of information is available to assist in validating what therapies to use.

What the NCI says:

“When doctors discuss a person’s prognosis, they carefully consider all factors that could affect that person’s disease and treatment, and then try to predict what might happen. The doctor bases the prognosis on information researchers have collected over many years about hundreds or even thousands of people with cancer. When possible, the doctor uses statistics based on groups of people whose situations are most similar to that of an individual patient.”

''So it would appear that published reports of clinical trials provide provide precious little in the way of guidance.''

What the NCI says:

“A clinical trial is one of the final stages of a long and careful cancer research process. Studies are done with cancer patients to find out whether promising approaches to cancer prevention, diagnosis, and treatment are safe and effective.”

''The use of clinical trials to establish prescribing guidelines for evidence-based medicine is highly criticized because such trials have little relevance for the individual patient in the real world, the individuality and uniqueness of each patient. The sample of participants in a randomized controlled trial is typically drawn from those deemed most likely to benefit from the protocol. It usually excludes the very young or old, the non-compliant, and those with co-existing illness. In clinical trials, many patients are excluded because they could not complete the rather arduous treatment. So randomized comparisons are of healthier treated patients against all the controls, rendering a lot of trials invalid. While the evidence obtained from the clinical trial may apply to the sample of trial participants, it may have little relevance for the individual patient in the real world.''

“The evidence that supports the validity or truthfulness of the information is found primarily in the study methodology. Here is where the investigators address the issue of bias, both conscious and unconscious. Study methodologies such as randomization, blinding and accounting for all patients help insure that the study results are not overly influenced by the investigators or the patients.

Once you have determined that the study methodology is valid, you must examine the results and their applicability to the patient. Clinicians may have additional concerns such as whether the study represented patients similar to his/her patients, whether the study covered the aspect of the problem that is most important to the patient, or whether the study suggested a clear and useful plan of action.

Anything that happens after randomization can affect the chances that a patient in a study has an event. Patients who forget or refuse their treatment should not be eliminated from the study analysis. Excluding noncompliant patients leaves behind those that may be more likely to have a positive outcome, thus compromising the unbiased comparison that we got from the process of randomization. Therefore patients should be analyzed within their assigned groups. This is called "intention to treat" analysis.

Blinding means that the people involved in the study do not know which treatments are given to which patients. This eliminates bias and any preconceived notions as to how the treatments should be working. When it is difficult or unethical to blind patients to a treatment, such as a surgical treatment, then a "blinded" researcher is needed to interpret the results.

Decision making involves choosing an action after weighing the risks and benefits of the alternatives. While all clinical decisions are made under conditions of uncertainty, the degree of uncertainty decreases when the medical literature includes directly relevant, valid evidence. When the published evidence is scant, or less valid, uncertainty increases.

Decision analysis is the application of explicit, quantitative methods to analyzing decisions under conditions of uncertainty. Decision analysis allows clinicians to compare the expected consequences of pursuing different strategies.”

''There is no proof beyond reasonable doubt for any approach to treating advanced cancer today. There is only the bias of clinical investigators as a group and as individuals.''

There is no proof beyond a reasonable doubt that gravity exists or that the sun will rise tomorrow, so?

Some thoughts:

"In 1998, Dr. David Sackett, using an "evidence cart" on rounds, reported that of 71 information searches to answer clinical questions, 37 (52%) confirmed the management decision, but 18 (25%) lead to a new therapy or diagnostic test and 16 (23%) corrected a previous plan.” (Sackett D, 1998)

“Similar results were report by Crowley et al in 2003. The CAR study showed that of 520 clinical questions for which answers were sought in the medical literature, in 53% of these cases the literature confirmed the management decision, but in 47% of these cases the literature changed the medication, diagnostic test, or prognostic information given to the patient. (Crowley S, 2003)”

“According to G. Michaud, "Most primary therapeutic clinical decisions in 3 general medicine services are supported by evidence from randomized controlled trials. This should be reassuring to those who are concerned about the extent to which clinical medicine is based on empirical evidence. This finding has potential for quality assurance, as exemplified by the discovery that a literature search could have potentially improved these decisions in some cases." (Michaud G, 1998)

“The medical literature is immense, but only a small portion of it is immediately useful in answering clinical questions. The literature reports the whole spectrum of the scientific research process -- the long journey from in-vitro studies to double-blind randomized controlled trials. This has been called the "wedge of evidence" or the "pyramid of evidence."

“An understanding of how various levels of evidence are reported and how this literature is organized will help the searcher retrieve the highest levels of evidence for a particular clinical question. High levels of evidence may not exist for all clinical questions because of the nature of medical problems and research and ethical limitations.”

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