You may have noticed that men and women are different. I hope you have noticed. As the French say, vive la différence! It’s not just that one has dangly bits and the other has bumpy chests. Or that one has to shave a beard and doesn’t like to ask for directions while the other has menstrual periods and likes to discuss feelings. There are differences in physiology and in the incidence of various diseases. For instance, normal lab values for hemoglobin are higher for men than for women, and autism is more prevalent in males while multiple sclerosis is more prevalent in females.
In the past, women have been underrepresented in clinical studies; when the first studies of aspirin for cardiovascular prevention came out, we knew it was effective for men, but we didn’t have enough evidence to recommend it for women. This is changing; researchers today are more aware of the need to include women in their studies. Now the American Heart Association/American Stroke Association (AHA/ASA) has issued the first evidence-based guidelines for reducing the risk of stroke in women. (more…)
A Swedish researcher, Staffan Lindeberg, has been studying the inhabitants of Kitava, one of the Trobriand Islands of Papua New Guinea. He claims that sudden cardiac death, stroke, and exertion-related chest pain never occur in Kitava; and he attributes this to their eating a Paleolithic diet.
2,250 people live on Kitava. They are traditional farmers. Their dietary staples are tubers (yam, sweet potato and taro), fruit, fish, and coconut. They don’t use dairy products, alcohol, coffee, or tea. Their intake of oils, margarine, cereals, and sugar is negligible. Western foods constitute less than 1% of their diet. Their activity level is only slightly higher than in Western populations. 80% of them smoke daily and an unspecified number of them chew betel. The macronutrient composition of the Kitavan diet was estimated as 21% of total calories from fat, 17% from saturated fat, 10% from protein, and 69% from carbohydrates.
Lindeberg’s Kitava study examined a sample of 220 Kitavans aged 14-87 and compared them to healthy Swedish populations. They found substantially lower diastolic blood pressure, body mass index, and triceps skinfold thickness in the Kitavans. Systolic blood pressure was lower in Kitava than in Sweden for men over 20 and women over 60. Total cholesterol, LDL cholesterol, and apolipoprotein B were lower in men over 40 and in women over 60. Triglycerides were higher in Kitavans aged 20-39 than in Swedes of the same age. HDL was not significantly different. (more…)
A new review published in the BMJ once again opens the question of the risks vs benefits of daily aspirin as a prevention for heart attacks and strokes. The reviewers looked at nine randomized trials involving over 100,000 patients and found that aspirin is effective in reducing heart attacks and strokes, but also increases the risk of gastrointestinal bleeding and that in some patients this risk outweighs the benefit.
This is an old and enduring controversy, and one with significant public health ramifications. Aspirin is an anti-platelet agent – it inhibits platelets, the cell fragments in the blood that are the first line against bleeding, from aggregating (clumping together). Platelets aggregate in order to quickly stop bleeding from damaged veins or arteries. But they can also aggregate around cholesterol plaques in arteries, causing a large thrombus (blood clot) that can block off the artery, or that can break off and lodge in a downstream artery (an embolus) and cause a stroke or heart attack.
By inhibiting platelet aggregation daily aspirin reduces the risk of forming a thrombus or embolus, and thereby reduces the risk of heart attack or stroke. Of course, the real story is always more complex than our straightforward explanations. There is some research to suggest that the anti-inflammatory effects of aspirin may also be important to their role in reducing vascular risk. The relative contribution of anti-platelet and anti-inflammatory effects have not been fully teased out. Further, the anti-inflammatory effects of daily aspirin may have non-vascular benefits, like reducing the risk of some cancers.
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.
While manipulation of any kind has the potential to cause injury, stroke caused by neck manipulation is of greatest concern. Risk must always be weighed against benefit when upper neck manipulation is considered. Risk of stroke caused by neck manipulation is statistically low, but the risk is serious enough to outweigh benefit in all but a few rare, carefully selected cases.
When the RAND (Research and Development) organization published its review of the literature on cervical spine manipulation and mobilization in 1996, it concluded that only about 11.1% of reported indications for cervical spine manipulation were appropriate and that stroke and other serious complications occurred about 1.46 times per one million neck manipulations.1 In the same year, after examining 183 cases of vertebrobasilar stroke that occurred from 1934 through 1994 following neck manipulation, the National Chiropractic Mutual Insurance Company (NCMIC) concluded that “It has to be accepted that VBS [vertebrobasilar stroke] following SMT [spinal manipulative therapy] does occur.”2
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…)
The chiropractic industry must be feeling the pressure. Billboards, signs on the sides of buses, chiropractic victims’ organizations, and lawsuits are telling the world that chiropractic neck adjustments can cause strokes. The risk is very small, but it is very real. We have addressed the subject before on this blog here, here, and here.
Chiropractors are in denial and are trying to shift the blame elsewhere. A correspondent sent me copies of a pamphlet and a “distribution kit” that the FCER (Foundation for Chiropractic Education and Research) is selling to chiropractors so they can inform the public about cervical artery dissection (CAD). It is advertised as a campaign to help the public recognize warning signs of stroke; but in my opinion, it amounts to a cynical, self-serving ploy to divert attention away from neck manipulation and to spread biased information about the recent study in Spine by Cassidy et al. (more…)
Over 26 million Americans are taking statin drugs. Some people think they should be available over-the-counter without a prescription, and it has even been facetiously suggested that they should be added to our drinking water. The protective effect of statins in cardiovascular disease and in high-risk patients with high cholesterol levels is well established. But what about people with no heart disease and normal cholesterol levels – can they benefit too?
The New England Journal of Medicine has pre-released an important new study on statins online prior to its planned publication date of November 20, 2008. It is certain to stir up a lot of controversy, and the International Network of Cholesterol Skeptics will not be happy, because it contradicts some of their favorite arguments. They have claimed that statins do more harm than good, that reducing cholesterol levels is harmful to health, that the benefits of statins and/or cholesterol lowering do not extend to women and the elderly, and that studies showing benefits of statins are meaningless because they do not show reduction of overall mortality. This study indicates otherwise. (more…)
Sandra Nette is a prisoner, condemned to spend the rest of her life in the cruelest form of solitary confinement. Her intact mind is trapped in a paralyzed body and she is unable to speak. She can move one arm just enough to type on a special keyboard. She cannot swallow or breathe on her own, and must be frequently suctioned. She feels sensations and is in pain. Her condition is known as “locked-in syndrome” and has been described as “the closest thing to being buried alive.” She is suing those responsible for her cruel fate and I hope she wins.
She was a healthy 40 year old woman who wanted to stay healthy. She did all the right things like watching her weight, eating right, and not smoking. She followed the advice of a chiropractor to include regular maintenance chiropractic adjustments in her health regimen. On September 13, 2007 she had the last adjustment she would ever have.
There was nothing wrong with her. She didn’t see the chiropractor for headaches, neck pain, back pain or any other complaint. She went for a “tune-up” that she thought would help keep her healthy. The chiropractor did a rapid-thrust adjustment on her neck. Right afterwards, she complained of feeling “sore, dizzy and unwell.” She tried to leave but had to sit down. The chiropractor failed to recognize the medical emergency, and instead of calling an ambulance he recommended that she would benefit from purchasing massage therapy from his clinic. He let her leave the office and drive home alone. She only made it part way. (more…)