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Archive for Clinical Trials

When impressive science fails to impress patients

One of the greatest challenges in medicine can sometimes be to convince patients that the results of scientific and medical research apply to them, or, at the very least, to explain how such results apply. One of the reasons that medicine based not on science or evidence fluorishes is because it can be so hard to explain to patients why a particular intervention is viewed as effective. My co-blogger Steve Novella wrote about some of the fallibilities of human perception that lead to perceiving correlations and treatment effectiveness where there are none. R. Robert Bausell wrote about the same thing in his recent book Snake Oil Science. While it is undoubtedly true that people tend to pay more attention to anecdotes than to studies and statistics, there is also another reason why doctors often have problems convincing patients of the value of health interventions, and that’s the difference in perception and how we value different kinds of evidence.

A couple of years ago, I came across an article that explains this gulf between how those of us trying to practice science- and evidence-based medicine perceive the world and how most human beings not trained in medicine or science perceive it. The article, which was published in 2006 in the New York Times and written by Dr. Abigail Zuker, proposed one reason why this might be, beginning with a discussion with her mother in which she tries to convince her of the benefit of exercise, even in the elderly, a concept that her mother would have none of and dismissed contemptuously:

“Studies,” she says, dripping scorn. “Don’t give me studies. Look at Tee. Look at all the exercise she did. She never stopped exercising. Look what happened to her.”

End of discussion. Tee, her old friend and contemporary, took physical fitness seriously, and wound up bedbound in a nursing home, felled by osteoporosis and strokes, while my mother, who has not broken a sweat in the last 60 years, still totters around on ever-thinning pins. So much for exercise. So much for studies. So much for modern clinical medicine, based on the randomized allocation of treatment and placebo. All that beautiful science, stymied by the single, incontrovertible, inescapable image of Tee, the one who exercised but grew hunched and crippled anyway.

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Posted in: Clinical Trials, Public Health, Science and Medicine

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Do Antidepressants Work? The Effect of Publication Bias

A recent meta-analysis of the most commonly prescribed antidepressant drugs raises some very important questions for science-based medicine. The study: Initial Severity and Antidepressant Benefits: A Meta-Analysis of Data Submitted to the Food and Drug Administration, was conducted by Irving Kirsch and colleagues, who reviewed clinical trials of six antidepressants (fluoxetine, venlafaxine, nefazodone, paroxetine, sertraline, and citalopram). They looked at all studies submitted to the FDA prior to approval, whether published or unpublished. They found:

Drug–placebo differences in antidepressant efficacy increase as a function of baseline severity, but are relatively small even for severely depressed patients. The relationship between initial severity and antidepressant efficacy is attributable to decreased responsiveness to placebo among very severely depressed patients, rather than to increased responsiveness to medication.

The press has largely reported this study as showing that “antidepressants don’t work” but the full story is more complex. This analysis certainly has important implications for how we should view the body of evidence for these antidepressants. It also illuminates the possible role of publication bias in the body of scientific literature – something that has far ranging implications for science-based medicine.

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Posted in: Clinical Trials, Neuroscience/Mental Health, Pharmaceuticals, Science and Medicine

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RCT Plausibility Scale

RCT Plausibility Scale

After a few intro paragraphs, I want to present a scale of probability to estimate a value of a “prior” to plug into the formula for obtaining a Bayes Factor. The scale can help to estimate a value, but will still rely on an estimate, the non-quantitative element in Bayesian simulations. However, the checklist may at least provide some objective bases on which to hang a value, and that value would actually make a semi-quantitative statement of its own. Although that value would retain some subjective quality, it would at least be backed by known quantities and laws of nature.

Begging your patience again, I became aware of this problem in 1999 when asked to moderate an online (BioMednet.com) debate on “CAM” among 4 physicians. My role soon morphed into participant-debater when I could not get all to agree on what I thought was obvious common ground to proceed with the discussion – that 1) concepts that violate scientific laws do not have to be subjected to clinical trial (RCT) and that trial results had to be interpreted in light of previous knowledge; and 2) clinical trials could not constitute adequate evidence in the absence of plausibility because their results were too varied and inconsistent. The matter was p-recipitated by systematic reviews (SRs) showing efficacy of acupuncture in back pain. I was truly surprised when one of the participants (Dr. Edzard Ernst) assured me that indeed, RCTs were now the gold standard for efficacy. The debate went downhill from there.

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Posted in: Clinical Trials, Science and Medicine

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Bad scientific arguments in the service of animal rights activism

One of the greatest threats to the preclinical research necessary for science-based medicine today is animal rights activism. The magnitude of the problem came to the forefront again last week with the news that animal rights terrorists tried to enter the home of a researcher at the University of California Santa Cruz (UCSC) whose research uses mice to study breast cancer and neurologic disease while she and her husband were having a birthday party for one of their children and assaulted her husband, who had gone to the front of the house to confront them. Fortunately, the license plate number of the car fleeing the scene was reported to police, leading to a raid on a house by police and the confiscation of computers and other materials. This attack appeared to be the latest crescendo in an increasing campaign of harrassment and intimidation by animal rights “activists” that has also been observed in nearby Berkeley.

This sort of threat to researchers is not a problem just in Santa Cruz and the Bay area, but in particular has been a problem in southern California as well. Just earlier this week, the University of California Los Angeles announced that it was suing several animal rights groups and individuals suspected of attacks on researchers who use animals, including UCLA Primate Freedom Project, the Animal Liberation Front (ALF), and the Animal Liberation Brigade (ALB), as well as several individuals believed to affiliate with these groups. The inciting event for this action was the second attack on the home of Edythe London, Professor of Psychiatry and Bio-behavioral Sciences and of Molecular and Medical Pharmacology at the David Geffen School of Medicine at UCLA, in early February. Her research involves the use of primate models to study nicotine addiction. In this most recent attack, an attempt was made to set her house on fire. This came on the heels of a previous attack in October, in which animal rights activists flooded her house. Prior to that, animal rights terrorists had indeed succeeded in their aim of intimidating a scientist sufficiently that he gave up animal research after a fellow researcher was targeted with a Molotov cocktail meant for her home that was mistakenly placed on the porch of an elderly neighbor. Also, we in the U.S. often forget how much more radical animal rights extremists are in the U.K., where the campaign of intimidation takes the form of death threats, intimidation of personnel of companies that supply researchers, and even in one case digging up the grave of Gladys Hammond, whose family ran a farm that raised Guinea pigs for use in medical research, and stealing her remains.

Readers may make the argument that my introduction to this discussion is unfairly inflammatory, but I have my reasons for starting this way, and I think they are good ones. First, make no mistake, the aim of the most radical of these activists is nothing short of the cessation of the use of all animals in biomedical research. Second, sooner or later, someone will be hurt or killed. As a researcher who on occasion uses mouse models of cancer myself, I state up front that I could be on the firing line just as much as the UCSC researcher or others and am justifiably disturbed when I hear spokesperson for the ALF Dr. Jerry Vlasak, for example, repeatedly advocate violence against researchers who use animals. In this article, I am not going to discuss the moral issues involved in animal research. What I am going to discuss is the seemingly scientific arguments that some opponents of animal research and animal rights activists like to invoke, arguments increasingly used in addition to the moral arguments that extremists use to justify their actions. If the arguments of opponents of animal rights research were indeed good science, then their appropriation by extremists would not allow me to do much other than bemoan the misuse of valid science as a justification for extremism. Unfortunately, such is not the case, and the bad scientific arguments used by opponents of animal research are often piled onto the extreme moral arguments that fuel actions such as those earlier this week at UCSC. Consequently, given the events of the last month or so, I thought I would take this opportunity to look at some of the common scientific indictments of animal research by its opponents.
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Posted in: Basic Science, Clinical Trials, Politics and Regulation, Science and Medicine

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Glucosamine Update: A New Study and a New Product

ResearchBlogging.orgWhen I recently wrote about glucosamine, I discussed the evidence up through the New England Journal of Medicine study of 2006, which I thought was a pretty definitive study showing that neither glucosamine, chondroitin or a combination of the two was more effective than placebo.  Subsequent studies have continued to fuel the controversy. One 2007 study showed that glucosamine sulfate was better than placebo for knee osteoarthritis.  Another 2007 study showed that glucosamine HCl and chondroitin, with or without exercise, were no better than placebo for knee osteoarthritis. Sources like the Natural Medicines Comprehensive Database believe the evidence favors glucosamine sulfate but not glucosamine hydrochloride.

A new study was published 19 February 2008 in the prestigious Annals of Internal Medicine.  It is arguably the best study to date, and may shed some light on the controversy. Carried out in the Netherlands in a primary care setting, it studied 222 patients with hip osteoarthritis over a 2 year period. Half the patients took glucosamine sulfate 1500 mg a day; half took a placebo. They concluded that glucosamine sulfate was no better than placebo in reducing symptoms and progression of hip osteoarthritis. (more…)

Posted in: Clinical Trials, Herbs & Supplements

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When the popularity of new surgical procedures outpaces science

ResearchBlogging.orgIn science- and evidence-based medicine, the evaluation of surgical procedures represents a unique challenge that is truly qualitatively different from the challenges in medical specialties. Perhaps the most daunting of these challenges is that it is often either ethically unacceptable or logistically impossible to do the gold-standard clinical trial, a double-blind, randomized placebo trial for an operation. After all, the “placebo” in a surgical trial involves patients to anaesthesia, making an incision or incisions like the ones used for the operation under study, and then not doing the operation. Clearly, even leaving the ethics aside, it’s impossible to blind the surgeons and operative team involved to which treatment, real surgery or placebo, the patient is receiving without having a different surgeon do the surgery from the one overseeing the postoperative care of the patient, with the operative surgeon barred from communicating to the postoperative surgeon what happened in the operating room and from participating in the postoperative care of the patient upon whom he operated. This sort of restriction, besides being also highly dubious ethically speaking, goes against the grain of surgical culture, in which a surgeon is expected to provide the postoperative care for his patients almost as a matter of surgical honor. A final problem that complicates any surgical trial is that surgeons of differing technical operating skill will necessarily be involved, and surgical skill is indeed very important in determining outcome. Although there have been examples of double-blinded trials with sham surgery as placebo, for example, in injecting dopamine-producing cells into the brain to treat Parkinson’s disease, difficulties doing such studies tend to force us as surgeons in many cases either to rely on retrospective data, prospective non-randomized data, or, when we’re lucky, a prospective randomized (but not double-blinded) trial of one surgical procedure versus another.
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Posted in: Clinical Trials, Medical Ethics, Science and Medicine, Surgical Procedures

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Prior Probability: the Dirty Little Secret of “Evidence-Based Alternative Medicine”—Continued

This is an addendum to my previous entry on Bayesian statistics for clinical research.† After that posting, a few comments made it clear that I needed to add some words about estimating prior probabilities of therapeutic hypotheses. This is a huge topic that I will discuss briefly. In that, happily, I am abetted by my own ignorance. Thus I apologize in advance for simplistic or incomplete explanations. Also, when I mention misconceptions about either Bayesian or “frequentist” statistics, I am not doing so with particular readers in mind, even if certain comments may have triggered my thinking. I am quite willing to give readers credit for more insight into these issues than might be apparent from my own comments, which reflect common, initial difficulties in digesting the differences between the two inferential approaches. Those include my own difficulties, after years of assuming that the “frequentist” approach was both comprehensive and rational—while I had only a cursory understanding of it. That, I imagine, placed me well within two standard deviations of the mean level of statistical knowledge held by physicians in general.

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Posted in: Clinical Trials, Medical Academia, Science and Medicine

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Prior Probability: The Dirty Little Secret of “Evidence-Based Alternative Medicine”

This is actually the second entry in this series;† the first was Part V of the Homeopathy and Evidence-Based Medicine series, which began the discussion of why Evidence-Based Medicine (EBM) is not up to the task of evaluating highly implausible claims. That discussion made the point that EBM favors equivocal clinical trial data over basic science, even if the latter is both firmly established and refutes the clinical claim. It suggested that this failure in calculus is not an indictment of EBM’s originators, but rather was an understandable lapse on their part: it never occurred to them, even as recently as 1990, that EBM would soon be asked to judge contests pitting low powered, bias-prone clinical investigations and reviews against facts of nature elucidated by voluminous and rigorous experimentation. Thus although EBM correctly recognizes that basic science is an insufficient basis for determining the safety and effectiveness of a new medical treatment, it overlooks its necessary place in that exercise.

This entry develops the argument in a more formal way. In so doing it advocates a solution to the problem that has been offered by several others, but so far without real success: the adoption of Bayesian inference for evaluating clinical trial data.
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Posted in: Basic Science, Clinical Trials, Homeopathy, Science and Medicine

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Another Acupuncture Study – On Heartburn

Blogging on Peer-Reviewed ResearchPatients with heartburn are often diagnosed with GERD (gastroesophageal reflux disease) and treated with a drug called a proton pump inhibitor (PPI) to reduce stomach acid production. It is pretty effective, but it doesn’t always work. When it doesn’t, standard practice has been to double the dose of PPI. Doubling the dose only improves symptoms in 20-25%. Most patients who fail the single dose turn out to have normal esophageal acid exposure, or “functional” heartburn. In other words, the symptoms appear to be due to something other than excess acid – so it really may not make much sense to double the PPI dose. What else could doctors try?

How about acupuncture? A recent clinical trial compared acupuncture to doubling the proton pump inhibitor dose in refractory heartburn. (more…)

Posted in: Acupuncture, Clinical Trials, Energy Medicine

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Hype over science: Does acupuncture really improve the chances of success for in vitro fertilization?

There it was on Friday greeting me on the ABC News website: “Study: Acupuncture May Boost Pregnancy” in bold blue letters, with the title of the webpage being “Needles Help You Become Pregnant.” The story began:

It sounds far-fetched sticking needles in women to help them become pregnant but a scientific review suggests that acupuncture might improve the odds of conceiving if done right before or after embryos are placed in the womb.

The surprising finding is far from proven, and there are only theories for how and why acupuncture might work. However, some fertility specialists say they are hopeful that this relatively inexpensive and simple treatment might ultimately prove to be a useful add-on to traditional methods.

By the end of the day, the story was all over the media, including radio, TV, news websites, the blogosphere, and various other outlets, all trumpeting the message that a scientific study says that acupuncture can help infertile couples conceive. Nary a skeptical word seemed to be found. Knowing very well just how far parents will go to conceive, I was curious: Did this study actually say what the media says it said? What was so new and radical about this study that it rated a press release and a lot of promotion? Do we here at SBM (particularly Steve) need to rethink our extreme skepticism about acupuncture, given the poor quality evidence and lack of even a glimmer of a convincing physiologic mechanism to explain its supposed activities?
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Posted in: Acupuncture, Clinical Trials, Energy Medicine, Science and Medicine, Surgical Procedures

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