Tylenol (acetaminophen, also known as paracetamol outside the US) has been in the news recently. Most of the stories I’ve seen have been accurate, but I’ve run across a couple of people who misunderstood what they read. I thought I’d try to put the record straight.
An FDA advisory panel has recommended reducing the maximum allowed single dose from 1000 mg to 650 mg in over-the-counter acetaminophen products. The 1000 mg dose would be available by prescription only. They also recommended eliminating painkillers like Percocet and Vicodin that contain a combination of a narcotic and acetaminophen. They did not recommend removing acetaminophen from over-the-counter cold remedies, cough medicines and similar products that combine acetaminophen with other drugs. Advisory panel recommendations are not binding, but the FDA usually follows them.
Some people got the impression that the FDA had just discovered that acetaminophen can be dangerous. No, we always knew that. The danger is when you take too much: it can damage the liver. The “new” information is just that acetaminophen overdose is now the leading cause of liver damage, causing an estimated 1600 cases of liver failure each year. (more…)
So many of the posts on this blog are critical and deal with examples of poor science or other problems. I’d like to offer a breath of fresh air in the form of a book by Mark Sloan, MD: Birth Day: A Pediatrician Explores the Science, the History, and the Wonder of Childbirth.
It is a very positive book. Sloan has attended over 3000 deliveries but he has not lost his sense of wonder. He tells us what life is like in the womb – how much the fetus can see and hear – and smell! He explains the labor process. He explains how a fetus has to rapidly adapt to life outside the womb with a number of physiologic changes. He reflects the joy of bringing a new life into a family, and the experience of becoming a father. He delves into the history of childbirth, with fascinating anecdotes about “salting” newborns, Queen Victoria’s influence on obstetric analgesia, and the attempt to keep forceps a proprietary secret of one family.
He shows the many contributions science has made to childbirth, some of the mistakes it made along the way, and how it corrected those mistakes. (more…)
A study published in Alternative Therapies in Health and Medicine is being cited as evidence for the efficacy of healing touch (HT). It enrolled 237 subjects who were scheduled for coronary bypass, randomized them to receive HT, a visitor, or no treatment; and found that HT was associated with a greater decrease in anxiety and shorter hospital stays.
This study is a good example of what I have called “Tooth Fairy Science.” You can study how much money the Tooth Fairy leaves in different situations (first vs. last tooth, age of child, tooth in baggie vs. tooth wrapped in Kleenex, etc.), and your results can be replicable and statistically significant, and you can think you have learned something about the Tooth Fairy; but your results don’t mean what you think they do because you didn’t stop to find out whether the Tooth Fairy was real or whether some more mundane explanation (parents) might account for the phenomenon. (more…)
It’s easy to think of medical tests as black and white. If the test is positive, you have the disease; if it’s negative, you don’t. Even good clinicians sometimes fall into that trap. Based on the pre-test probability of the disease, a positive test result only increases the probability by a variable amount. An example: if the probability that a patient has a pulmonary embolus (based on symptoms and physical findings) is 10% and you do a D-dimer test, a positive result raises the probability of PE to 17% and a negative result lowers it to 0.2%.
Even something as simple as a throat culture for strep throat can be misleading. It’s possible to have a positive culture because you happen to be an asymptomatic strep carrier, while your current symptoms of fever and sore throat are actually due to a virus. Not to mention all the things that might have gone wrong in the lab: a mix-up of specimens, contamination, inaccurate recording…
Mammography is widely used to screen for breast cancer. Most patients and even some doctors think that if you have a positive mammogram you almost certainly have breast cancer. Not true. A positive result actually means the patient has about a 10% chance of cancer. 9 out of 10 positives are false positives.
But women don’t just get one mammogram. They get them every year or two. After 3 mammograms, 18% of women will have had a false positive. After ten exams, the rate rises to 49.1%. In a study of 2400 women who had an average of 4 mammograms over a 10 year period, the false positive tests led to 870 outpatient appointments, 539 diagnostic mammograms, 186 ultrasound examinations, 188 biopsies, and 1 hospitalization. There are also concerns about changes in behavior and psychological wellbeing following false positives.
Until recently, no one had looked at the cumulative incidence of false positives from other cancer screening tests. A new study in the Annals of Family Medicine has done just that. (more…)
In May 2008, the article “Why the NIH Trial to Assess Chelation Therapy (TACT) Should Be Abandoned” was published online in the Medscape Journal of Medicine. The authors included two of our own SBM bloggers, Kimball Atwood and Wallace Sampson, along with Elizabeth Woeckner and Robert Baratz. It showed that the existing evidence on treating heart disease with IV chelation did not justify further study, and that the TACT trial was questionable on several ethical points. Their ethical concerns were taken seriously enough that enrollment in the trial was put on hold pending an investigation. It has now been re-opened after a few band-aids were applied to the ethical concerns. The scientific concerns were never addressed.
I have seen many critiques of the Atwood study, and not a single one has offered any cogent criticism of its factual content or reasoning. Most of them could have been written by someone who had not bothered to read beyond the title. Their arguments can be boiled down to a few puerile points that can be further simplified to:
(1) I believe the testimonial evidence that chelation works.
(2) Atwood and his co-authors are bad guys.
Now Beth Clay has chimed in with an article entitled “Study of Chelation Therapy Should Not Be Abandoned.” I found it truly painful to read, but even the worst has some value as a bad example. Clay’s article could be used for a game of “Count the Errors.” I will point out some of them below. (more…)
A new book, Science Under Siege: Defending Science, Exposing Pseudoscience addresses many of the issues near and dear to the hearts of SBM bloggers and readers. A compilation of some of the best writing from the last few years of Skeptical Inquirer magazine, it’s not only good reading but can serve as a useful reference.
Skeptical Inquirer is the official magazine of what was formerly called The Committee for the Skeptical Investigation of Claims of the Paranormal (CSICOP). It was formed in 1976 and in its early days it concentrated on things like Bigfoot, UFOs and psychics. It has morphed into the Committee for Skeptical Inquiry and the magazine is now described on its cover as “The Magazine for Science and Reason.” It has gone way beyond paranormal claims to address everything from intelligent design to AIDS denial. In the 3 decades of its existence it has performed an invaluable service by investigating alleged phenomena and testing claims scientifically, providing natural explanations for weird observations, refuting pseudoscientific arguments, and teaching people how science works and how to think critically.
We now have many skeptical magazines, including Michael Shermer’s Skeptic in the US and similarly named publications in the UK, Australia and elsewhere. But Skeptical Inquirer was the first. It was the trailblazer and set the standard.
The word “skeptic” has negative connotations for some. But it is really a positive, inquisitive, reality-based approach to all aspects of life. A skeptic is a person who asks for evidence before accepting a belief and who asks if there could be another explanation other than the first one that is offered. Scientists are skeptics. Skeptics think scientifically. (more…)
I was recently asked to write about vaccines and autism for Skeptic magazine. I approached the project with trepidation. So much has been written, from Paul Offit’s book Autism’s False Prophets to a veritable flood of blogorrhea on the Internet. I didn’t have anything new to add, and I couldn’t hope to cover all aspects of the subject.
After some thought, I realized I could contribute something useful. I could organize the highlights into a concise and accessible story. While it awaits publication in the magazine, Michael Shermer elected to pre-publish it in the e-Skeptic newsletter. You can read it here.
There is a very good chance that you will feel worse after seeing a chiropractor.
According to a new systematic review, serious complications of spinal manipulation are rare, but 33-60% of patients experience milder short-term adverse effects such as increased pain, radiation of pain, headaches, vertigo and even loss of consciousness. The study, published in the journal Spine, involved searching PubMed and the Cochrane Library for the years 1966 to 2007. They identified additional studies by hand searching. They looked for all articles that reported adverse effects associated with chiropractic irrespective of type of design. They omitted any reports where patients had underlying diseases (osteogenesis imperfecta, expansive vertebral hemangioma, osteoporotic fracture, etc.) that predisposed them to complications with manipulation.
They found 46 pertinent studies:
- One randomized controlled trial
- Two case-control studies
- Six prospective studies
- Twelve surveys
- Three retrospective studies
- 115 case reports
They recognized that “the heterogeneity of the study designs did not allow conducting a formal meta-analysis.” But they did the best they could to make sense out of what they found. (more…)
Last month I wrote about a book on evolutionary medicine that I could not recommend. Now I’ve found one I can recommend. Marlene Zuk, an evolutionary biologist at the University of California, Riverside, has written a delightful book entitled Riddled with Life: Friendly Worms, Ladybug Sex, and the Parasites That Make Us Who We Are. She describes how our parasites and diseases co-evolved with us: as we developed better defenses, they developed better weapons. “We do not choose to have them, but our lives are unimaginable without them, and for better or worse, they have made us who we are.” Parasites have altered our bodies in ways that science fiction filmmakers could never have imagined. She even suggests that we can thank parasites for the fact that we reproduce sexually rather than asexually.
She advocates an evolutionary medicine that “places diseases and defects in an evolutionary framework to make sense of the apparent mismatch between the way our bodies often work and the way we would like them to.” Evolution did not design our bodies for health, but to maximize reproduction.
“Just because our species evolved in a different environment does not mean …that following the ways of the past is automatically going to free us from the illnesses of modern life.” She incisively debunks the myth of the Paleolithic diet and points out that if we wanted to copy our hunter-gatherer ancestors we would have no way of deciding which ones to copy – the ones from 10,000 years ago or the ones from 100,000 years ago; the Inuits or the Kalahari Bushmen. She also points out that evolution explains why humans vary and why one diet won’t suit everyone. (more…)
Alcoholics Anonymous is the most widely used treatment for alcoholism. It is mandated by the courts, accepted by mainstream medicine, and required by insurance companies. AA is generally assumed to be the most effective treatment for alcoholism, or at least “an” effective treatment. That assumption is wrong.
We hear about a few success stories, but not about the many failures. AA’s own statistics show that after 6 months, 93% of new attendees have left the program. The research on AA is handily summarized in a Wikipedia article. A recent Cochrane systematic review found no evidence that AA or other 12 step programs are effective.
In The Skeptic’s Dictionary, Bob Carroll comments:
Neither A.A. nor many other SATs [Substance Abuse Treatments] are based on science, nor do they seem interested in doing any scientific studies which might test whether the treatment they give is effective. (more…)