A recent study published in the Archives of Opthalmology compare patching of one eye vs acupuncture in the treatment of amblyopia in older children, and finds positive results from acupuncture. The study, and its press, are a good example of the hazards of studying highly implausible modalities.
First let’s dissect the study itself – from the abstract:
In a single-center randomized controlled trial, 88 eligible children with an amblyopic eye who had a best spectacle-corrected visual acuity (BSCVA) of 0.3 to 0.8 logMAR at baseline were randomly assigned to receive 2 hours of patching of the sound eye daily or 5 sessions of acupuncture weekly. All participants in our study received constant optical correction, plus 1 hour of near-vision activities daily, and were followed up at weeks 5, 10, 15, and 25. The main outcome measure was BSCVA in the amblyopic eye at 15 weeks.
For background, amblyopia occurs when the brain tends to ignore visual information from one eye. This results from a variety of causes, but commonly from the two eyes having different refractive errors (anisometropic) – one eye may be more near-sighted or far-sighted than the other. The brain cannot combine information from both eyes, so it ignores one. This can be corrected in younger children, up to age 7, by correcting the vision for the refractive problems. If visual correction alone is not enough, then patching one eye (the strong eye) to force the brain to use the weak eye can be effective. This is usually done for only 2 hours a day, otherwise amblyopia of the patched eye can occur.
Cell phones continue to be a focus of epidemiological studies and public concern, despite the fact that so far there is no compelling evidence of any health risk from cell phones. Concerns are likely to be sparked anew with the report of a study linking cell phone use to behavioral problems in children.
The study, by Divan, Kheifets, Obel, and Olsen, is a follow up of a prior study which showed a correlation between cell phone use in pregnant women and behavior problems in their children. They sought to replicate this study with a larger data set and taking into consideration more possible confounding factors. They found:
Results The highest OR for behavioural problems were for children who had both prenatal and postnatal exposure to cell phones compared with children not exposed during either time period. The adjusted effect estimate was 1.5 (95% CI 1.4 to 1.7).
Conclusions The findings of the previous publication were replicated in this separate group of participants demonstrating that cell phone use was associated with behavioural problems at age 7 years in children, and this association was not limited to early users of the technology. Although weaker in the new dataset, even with further control for an extended set of potential confounders, the associations remained.
I have the pleasure of announcing that this is the 1000th post of Science-Based Medicine. The first post introducing the blog was on January 1st 2008 – almost three years ago. We have published steadily since then, and this post marks number 1000.
I would like to take this time to thank the many regular contributors and editors who have added to the success of SBM, as well as the regular readers and commenters. I would especially like to thank David Gorski, the managing editor, who has done much of the day-to-day management of SBM and is largely responsible for its growth.
We have plans to continue to build SBM into a better and better resource for science in medicine. We are just getting started, so stay tuned.
The controversy over the human consumption of meat and dairy products from cloned cows continues. The UK Advisory Committee on Novel Foods and Processes, after reviewing the evidence, concluded that there was no substantial difference between meat and dairy from cloned cows compared to conventional cows. However, food products from cloned animals and their offspring remain banned in Europe.
Use of offspring of cloned cows, sheep and pigs are legal in the US, South America, and Asia. Australia is likely to follow suit in a year or two. The European Union (EU) has an effective ban at the moment, but the policy is under review. The UK is also negotiating with the EU regarding the use of clones.
There is not much of a theoretical reason to suspect that cloned animals would present a health risk. The primary concern is that something unanticipated might have occurred during the cloning process, causing the animal to be genetically or developmentally abnormal. However, if the cloning process works properly this should not happen. Further, if mutations do occur, but the animal lives, it is likely that any changes do not represent a risk to humans who consume the meat or dairy from such clones.
One of the core features of science (and therefore science-based medicine) is to precisely identify and control for variables, so that we know what, exactly, is exerting an effect. The classic example of this principle at work is the Hawthorne effect. The term refers to a series of studies performed between 1924 and 1932 at the Hawthorne Works. The studies examined whether or not workers would be more productive in different lighting conditions. So they increased the light levels, observed the workers, and found that their productivity increased. Then they lowered the light levels, observed the workers, and found that their productivity increased. No matter what they did, the workers improved their productivity relative to baseline. Eventually it was figured out that observing the workers caused them to work harder, no matter what was done to the lighting.
This “observer effect” – an artifact of the process of observation – is now part of standard study design (at least well-designed studies). In medical studies it is one of the many placebo effects that need to be controlled for, in order to properly isolate the variable of interest.
There are many non-specific effects – effects that result from the act of treating or evaluating patients rather than a physiological response to a specific treatment. In addition to observer effects, for example, there is also the “chearleader” effect from encouraging patients to perform better. There are training effects from retesting. And there are long-recognized non-specific therapeutic effects just from getting compassionate attention from a practitioner. It is a standard part of medical scientific reasoning that before we ascribe a specific effect to a particular intervention, that all non-specific effects are controlled for and eliminated.
One of the recurrent themes of science-based medicine is that any medical intervention that can plausibly cause physiological benefit can also plausibly cause physiological harm. There is no such thing as “it can’t hurt.” Sometimes the risk may be minuscule – but we should never assume that it is zero. Being “natural” or “holistic” or being blessed with some other alleged marketable virtue does not affect the risk vs benefit calculation of an intervention.
Vitamins are an excellent example. There is widespread sentiment that vitamins are harmless, and that supplementing with vitamins is therefore a no risk-possible benefit scenario. It is certainly reasonable to conclude from the evidence that vitamins (at usual supplemental levels) are low risk, compared to many other types of medical interventions. High doses, or megadoses, of vitamins, however, risk toxicity and this risk increases with the dose.
But even at sub-toxic doses vitamins should not be assumed to be risk free. This is especially true when we take a public health perspective – what is the net effect of large scale supplementation on the population? A new meta-analysis looking at the net effects of Vitamin E supplementation on stroke risk reinforces this caution.
Most shots in the dark miss. Scientists learn this early in their career – most of the guesses we make as to how things work will turn out to be wrong. In fact, a proper understanding of science requires thorough knowledge of all the ways in which humans deceive themselves into believing things that are not true. In fact, most shots in well-lit conditions (informed by prior knowledge) miss. Ignoring prior knowledge results in chances that are all but hopeless.
Therefore the title of the 1985 book DPT: A Shot in the Dark by Harris Coulter and Barbara Loe Fisher, is perhaps unintentionally ironic. The book sparked the first modern popular concern about the risk of neurological damage from vaccines, in this case the pertussis vaccine that is part of the DTP vaccine.Fisher, of the National Vaccine Information Center (NVIC) still promotes the book and its content, even though the science has progressed in the last 25 years.
At the time the whole cell pertussis vaccine was part of the diptheria, tetanus, pertussis vaccine (DTwP). This combination has been largely replaced with the DTaP vaccine, which contains an acellular pertussis component. This change was partly due to safety issues, rare cases of neurological disease (seizures and encephalopathy) following DTwP being given. DTaP has a lower incidence of fever, seizures, and other side effects.
Over the last couple of days I have been engaged at NeuroLogica in a discussion with a fellow blogger, Marya Zilberberg who blogs at Healthcare, etc. Since the topic of discussion is science-based medicine I thought it appropriate to reproduce my two posts here, which contain links to her posts.
A Post-Modernist Response to Science-Based Medicine
I receive frequent commentary on my public writing, which is great. The feature that most distinguishes blogs is that they are conversations. So I am glad to see that science-based medicine (a term I coined) is getting targeted for criticism in other blogs. One blogger, Marya Zilberberg at Healthcare, etc., has written a series of posts responding to what she thinks is our position at Science-based medicine. What she has done, however, is make many of the logical fallacies typically committed in defense of unscientific medical modalities and framed them as one giant straw man.
She is partly responding to this article of mine on SBM (What’s the harm) in which I make the point that medicine is a risk vs benefit game. Ethical responsible medical practice involves interventions where there is at least the probability of doing more benefit than harm with proper informed consent, so the patient knows what those chances are. Using scientifically dubious treatments, where there is little or no chance of benefit, especially when they are overhyped, is therefore unethical. And further, the “harm” side of the equation needs to include all forms of harm, not just direct physical harm.
Tonight (Friday Night) we will be moving SBM to a new faster host. This will improve the performance of SBM, which has been sluggish recently, and give us the ability to increase our resources as needed as SBM continues to grow.
Comments posted between Friday night and approximately Sunday morning may be lost in the gap as the location of the new servers propagates through the internet. The site will be up throghout this process, but comments may be lost during this period. We are making the move over the weekend because that is when traffic is lowest. SBM should be fully functional by Monday morning, and in any case I will update this post when it appears that the move is complete.
Thanks for your patience.
The SBM move is now complete. If you are seeing this addendum then you are pointing to the new host. Performance seems much better already, but we will be closely monitoring it to keep performance optimal.
In my group practice, the Yale Medical Group, drug-company sponsored lunches and similar events have been banned. This is part of a trend, at least within academic medicine, to create some distance between physicians and pharmaceutical companies, or at least their marketing divisions. The justifications for this are several, and are all reasonable. One reason is the appearance of being too cozy, which compromises the role of academic physicians as independent experts.
But the primary reason is the belief that “detailing” by pharmaceutical sales representatives has a negative effect on the prescribing habits of physicians. There is reason to believe this may be the case because of cases of bad behavior on the part of pharmaceutical marketing divisions – ghost writing white papers, for example. The concern, backed by evidence, is that pharmaceutical companies introduce spin and bias into the information they provide to physicians, whether though CME, detailing, literature, or sponsored lectures. Even when the information itself is not massaged, it is cherry picked, so in the end physicians are not getting a thorough and unbiased assessment of the facts.
The FDA does heavily regulate the marketing of information about pharmaceuticals, but marketers are very clever about exploiting loopholes and seem to be one step ahead of the regulators.
On the other hand there are those who argue that physicians can handle access to information and they are equipped to take it with a grain of salt and put it into context. Certainly most physicians I speak to believe this about themselves. Further, information provided by pharmaceutical companies may actually improve prescribing habits if it makes physicians aware of new products on the market and new information about the drugs they prescribe. The information itself is FDA approved (or at least should be), even if it is selective and wrapped in spin.