Medicine is an uncertain business. It is an applied science, applying the results of basic science knowledge and clinical studies to patients who are individuals with differing heredity, environment, and history. It is commonly assumed that modern science-based doctors know what they are doing, but quite often they don’t know for certain. Different doctors interpret the same evidence differently; there is uncertainty about how valid the studies’ conclusions are and there is still considerable uncertainty and disagreement about things like guidelines for screening mammography and statin prescriptions.
Snowball in a Blizzard by Steven Hatch, MD, is a book about uncertainty in medicine. The title refers to the difficulty of interpreting a mammogram, trying to pick out the shadows that signify cancer from a veritable blizzard of similar shadows. (more…)
Whether you call them hot flashes or “power surges,” the symptoms of menopause can be very distressing. They were routinely treated with hormone replacement therapy (HRT) until the Women’s Health Initiative study in 2002 persuaded many patients and doctors to abandon that treatment. The results of that study were misunderstood by some and questioned by others, and there continues to be confusion about what the evidence shows and how menopausal symptoms should be treated. We have learned much more about this subject since 2002. HRT is still the most effective treatment and can be used safely under the new treatment guidelines.
The history of hormone replacement therapy
In the second half of the 20th century, there was much enthusiasm about estrogen. Mimicking the estrogen levels of a young woman was seen as a way to remain young and healthy. Doctors recognized that there were risks, but they seemed minor. There were studies showing that HRT protected women from the increased risk of heart disease after menopause. Few if any doctors prescribed it solely to prevent heart disease, but cardiovascular protection and osteoporosis prevention were seen as added benefits that served to tip the balance towards a decision to prescribe it for menopausal symptoms.
Then the Women’s Health Initiative study (WHI) dropped a bomb. It found that HRT didn’t protect women from cardiovascular disease after all. It showed that HRT did more harm than good. The number of prescriptions dropped by as much as 80%. Many women turned to alternative treatments that had not been studied anywhere near as extensively as HRT. (more…)
Back in 1943 a Dutch physician, David Karel de Jongh, wrote a PhD dissertation on homeopathy. It was based on his experience working in a homeopathic hospital and on all the published information he could find, and was highly critical of homeopathy. It was an impressive opus, with over 200,000 words. It is way too long for the average reader to wade through; and since it is in Dutch, few of us could read it even if we wanted to. Jan Willem Nienhuys, secretary of the Dutch skeptics’ organization Skepsis, has done us a great favor by summarizing its contents and updating it with information about recent developments. He has kindly had his summary translated into English and published in full on the Skepsis website. He comments “Basically Dr. de Jongh’s conclusions were that homeopathy is an incoherent mess.”
We all should know by now how monumentally silly homeopathy is (“delusions about dilutions”). I had investigated the subject and knew enough about it to have written about it repeatedly, but there is much more that I didn’t know. Nienhuys’ article is full of surprising facts and fascinating details. (more…)
We think of cancer as caused by mutations. Mutations are necessary, but not sufficient, to cause cancer. New research indicates that it’s the body’s response to mutant cells that determines whether cancer will develop. James S. Welsh, MD, a radiation oncologist and researcher, has written a book on the immunology of cancer, Sharks Get Cancer, Mole Rats Don’t: How Animals Could Hold the Key to Unlocking Cancer Immunity in Humans. In it, he pieces together clues from animals, pregnancy, Ebola virus, infections, organ transplantation, parasites, and human cancer patients, weaving a web of insights that point to a better understanding of cancer biology and treatment.
Sharks do get cancer
Shark with cancer
The first book claiming that sharks don’t get cancer came out in 1992. It persuaded so many people to take shark cartilage that the world market exceeded $30 million and shark populations decreased by as much as 80%. Sharks do get cancer, as you can see in this picture.
Ironically, sharks can even get cancer of the cartilage! And of course shark cartilage supplements don’t prevent cancer in humans. Welsh explains how that myth got started. It was magical thinking based on extrapolation from a legitimate scientific study on angiogenesis where tumor growth in lab animals was suppressed by placing rabbit cartilage next to the tumors.
I was approached by The Wall Street Journal to write an article for their Big Issues in Health Care debate series. The subject was “Is the annual physical unnecessary?” I was to take the “yes” side and an internist was to take the “no” side. I wrote the following article. The editor wrote me a couple of times with questions. The internist pointed out the value of preventive medicine, developing a personalized healthcare plan, and developing a meaningful doctor-patient relationship. I said I wholeheartedly agreed, but I thought those goals could be accomplished just as well (arguably even better) with a periodic health maintenance interview or consultation. I pointed out that the traditional “physical” exam with stethoscope, routine lab tests, etc. provides no further advantages and can be counterproductive, with false positive or harmless findings leading to unnecessary worry, further testing, and expense. I said there was nothing magical about the interval of a year. I don’t know what the optimum interval would be; that could be studied. I suspect it would vary with the patient’s age, medical conditions, risk factors, and other considerations, and might be left up to the judgment of patient and doctor deciding together.
Finally I got an e-mail with apologies, saying they had decided not to continue with the debate because the internist and I agreed on too many important details. While I understand that stirring up a fight is good for selling newspapers, I think it’s a much better thing when people on two sides of a debate reach an agreement. It reassures me that they are converging on the truth. So I thought it would be worthwhile to publish my article here on SBM. (more…)
Six years ago I wrote about the evidence for breastfeeding. I questioned an article that claimed 900 babies’ lives could be saved every year in the US if 90% of mothers breastfed for at least 6 months. I didn’t think that was true, but I did think the evidence supported the claim that breastfeeding was clearly better for babies. Now I’m not so sure we can trust that evidence.
A new study reevaluated the evidence from previous studies and found that the studies hadn’t adequately ruled out significant confounders. There are social, cultural and economic factors that contribute to the choice to breastfeed, factors that may have skewed the results of those studies to favor breastfeeding. The new study tried to correct for these issues.
Results from standard multiple regression models suggest that children aged 4 to 14 who were breast- as opposed to bottle-fed did significantly better on 10 of the 11 outcomes studied. Once we restrict analyses to siblings and incorporate within-family fixed effects, estimates of the association between breastfeeding and all but one indicator of child health and wellbeing dramatically decrease and fail to maintain statistical significance. Our results suggest that much of the beneficial long-term effects typically attributed to breastfeeding, per se, may primarily be due to selection pressures into infant feeding practices along key demographic characteristics such as race and socioeconomic status.
NOTE: Today we offer a double feature on the treatment of cervicogenic headache. My article is about a study that compared manipulation to mobilization; it is followed by retired chiropractor Sam Homola’s guest article on manipulation for cervicogenic headache. The two posts complement each other and also complement my post from last week on the possible risk of stroke with neck manipulation.
If a headache originates in the neck, does manipulation provide more relief than mobilization?
Cervicogenic headache (CGH) refers to headaches that are caused by problems in the neck, as opposed to headaches of non-neck etiology that may be accompanied by neck pain. There is controversy over whether CGH is even a valid diagnosis. Diagnostic criteria usually include unilateral headache triggered by head/neck movement or by pressure on the neck, headache that spreads to the neck, shoulder or arm; and often limited range of motion in the neck. If a nerve block in the neck relieves the headache, that would confirm that the pain originates in the neck, but nerve blocks are not routinely done and are not required for diagnosis.
Is manipulation effective for CGH?
There is controversy over whether spinal manipulation is an effective treatment for CGH. A 2005 systematic review concluded that “A greater number of well-designed, randomized, controlled trials are required to confirm or refute the effectiveness of spinal manipulation.” (more…)
Can neck manipulation (by chiropractors or by other practitioners) cause strokes? Many of us think it can, but definitive proof is lacking. A recently published study looked at the available evidence. A systematic review found a small association between stroke and chiropractic care but concluded that the association was spurious and that there was no evidence for causation. My colleagues and I have written about this subject several times; some of the links are listed here. I certainly agree that there is no definitive evidence for causation, but I think there is evidence to support a strong enough probability of causation to constitute a good reason to avoid neck manipulation. (more…)
One treatment for carotid artery stenosis: stent placement
The carotid artery in the neck is a common site of atherosclerosis. As plaque builds up, it leaves less room for blood flow and can cause strokes through clotting or embolization. Carotid stenosis is defined as a greater than 70% narrowing of the lumen (the space through which the blood flows in an artery). It can cause symptoms, including transient ischemic attacks (TIAs) and minor strokes; but it is frequently asymptomatic. It can be treated with carotid endarterectomy (CEA) or carotid angioplasty and stenting (CAAS). There has been much discussion about which procedure is better and when it is better not to do either. (more…)
Whatever is in this water, it isn’t testosterone
Ponce de Leon is said to have been looking for the Fountain of Youth when he explored Florida. That’s only a myth. Now there’s a new myth, that testosterone supplements are a Fountain of Youth for aging men. Men are urged to get their testosterone levels checked if they have any of a long laundry list of vague symptoms. Anti-aging clinics promote testosterone supplementation in many forms: prescription, bioidenticals from compounding pharmacies, natural remedies, testosterone boosters, and precursors. There are highly inflated estimates of the number of men who need supplementation, often relying on broadened criteria for diagnosis or non-standard lab tests. Testimonials abound: “My depression symptoms disappeared in 20 minutes when I started using Androgel.” (That one’s particularly hard to believe. Suggestion can be powerful.)
Until recently, evidence for the benefits of testosterone supplements was scanty, and there was concern about increased cardiovascular and prostate risks and other side effects. A 2013 study found that while testosterone was clearly indicated for younger men with classic hypogonadism caused by known diseases, a general policy of testosterone replacement in all older men with age-related decline in testosterone levels was not justified. In 2003 an Institute of Medicine panel called for a set of coordinated clinical trials to determine whether testosterone would benefit older men who had low testosterone levels for no known reason other than age and who had clinical conditions to which low testosterone might contribute. The results of those trials are starting to come in. The findings to date were covered in an article in the New England Journal of Medicine in February 2016. The full text is available online.