Denialism Blog

Category: Medicine

  • Migraines prevent breast cancer!!!!!!!

    ResearchBlogging.orgWhen reporting on science, reporters and editors like sexy stories. Since most science isn’t particularly sexy, there’s usually a hook. If you can squeeze “risk” and “cancer” into a headline, an editor sees good headline. What I usually see is a sensationalist article that is going to get it very wrong.

    One of the questions most often asked in the medical literature is “what is the risk of x?” It’s a pretty important question. I’d like to be able to tell my patient with high blood pressure what their risk of heart attack is, both with and without treatment. And risk is a sexy topic—the press loves it. Whether it’s cell phones and the “risk” of brain cancer, or vaccines and the “risk” of autism, risk makes for cool headlines. Take this one for example:

    Migraines cut breast cancer risk 30 percent: study

    What does this mean? Should I tell my wife to go out and find some migraines? What the hell is risk, anyway?

    Risk, in the most basic sense, is a causal association. If, for example, I find that members of the “Thunderstorm-lovers Golf Association” have a higher incidence of being struck by lightning than golfers who don’t belong to this odd club, I may have stumbled upon a measurable risk. There is both a measurable association, and a plausible reason to causally link the associated variables. If I find that members of the National Association of Philatelists have a higher incidence of heart disease than other folks, I may or may not have stumbled on a risk. Is there a reason that philatelists should have more heart disease? Is it a coincidence? Is it worth investigating further? Is there a confounding variable, e.g. are philatelists in general older, and did I fail to control for this?

    Then there is the question of the degree of risk. How strong is the risk observed?

    Statisticians have ways of measuring risk, but many of these terms—such as relative risk, absolute risk reduction, odds ratio—are not intuitive concepts.

    Let’s take the study in question. The premise is interesting. Migraines and breast cancer are both associated with estrogen. Many breast cancers are estrogen-dependent, and the risk of developing breast cancer correlates with exposure to estrogen.

    Migraines appear to be associated with estrogen as well, but negatively. This is a much more tenuous connection. It has been observed that migraines tend to wax during estrogen-poor times, and wane during estrogen-rich times—high estrogen, fewer migraines; low estrogen, more migraines. Or so it’s been observed.

    The authors of this study invoked migraine as a negative risk factor for breast cancer. The English meaning of “risk” is a bit lost here—what they are saying is that women who have migraines are less likely to develop breast cancer than women who don’t have migraines. This shouldn’t be all that surprising, as migraines and breast cancer are both associated with, well, womanhood.

    But all this aside, it’s the “30%” headline annoys me. That a big number! Get me a migraine, stat! But thirty percent is an “odds ratio“, which is a mathematical way of describing an association in a case-control study such as this one. Odds ratios are not intuitive, and as a measure of risk, they tend to break down when looking at common occurrences, such as migraines.

    If we look directly at the data from the study, the data used to calculate the odds ratio, we see something else. In this study, the control group was post-menopausal women without breast cancer. The case group was women with breast cancer. Among women without breast cancer, 19% had ever had a migraine. Among women with breast cancers, 14-15% had ever had a migraine. So, there was about a 4-5% difference in migraine rates between women with and without breast cancer. Does that still sound like a big number?

    Statistics are non-intuitive. I have to work pretty hard to try to dig out the clinical meaning from stats, and I still get it wrong sometimes. The press gets it wrong much more often. Be very wary of banner headlines about risk. Besides the difficulty of understanding the difference between risk reduction and odds ratios, what does it mean in the real world?

    To be perfectly frank, I think the authors have studied a question that no one is asking. We already know that estrogen is positively associated with breast cancer, and we suspect that estrogen reduces migraine frequency (maybe). What is the point of looking at the relationship between two secondary outcomes? In other words, if a and b are both dependent on c, does it even mean anything to say that a and b vary inversely? I don’t think so. Do you?

    References

    R. W. Mathes, K. E. Malone, J. R. Daling, S. Davis, S. M. Lucas, P. L. Porter, C. I. Li (2008). Migraine in Postmenopausal Women and the Risk of Invasive Breast Cancer Cancer Epidemiology Biomarkers & Prevention, 17 (11), 3116-3122 DOI: 10.1158/1055-9965.EPI-08-0527

  • Choosing a medical specialty

    It’s that time of year, 4th year medical students (like me – kind of) are choosing their future careers and starting to interview all over the country in their residency programs of choice. I’ve been notably quiet – subsumed in work, study and applications – but I am catching up on writing about the clerkships I’ve done in the meantime (Pediatrics, Psych, OB/Gyn and Family Medicine). But since I’m applying for residency now (MD/PhDs have an abbreviated 4th year) I figured now would be a good time to tell people about what this is like, and in the coming months what cities I’m going to be in from time to time.

    Choosing a medical specialty is a big decision. I’ve necessarily made up my mind, am very confident I’ve made the right choice and encourage you to take bets on my choice – it will be fun to see what people think. But the decision making process is famously difficult and many different strategies have been devised to help the indecisive (not me). Perhaps most famous is this chart first published in the BMJ by then-resident Boris Veysman:
    i-edbcd560d6996b5e5b969f2deb9aeb99-Medicalspecialty.gif

    If you’re very patient you can answer 130 redundant questions at this site offered by UVA to help you make up your mind, or read one of the books on the subject.

    Then there is the famous Goo index, which I think may be quite useful. Basically, chose your specialty based on which types of bodily fluid you can stand being in contact with every day for the rest of your life. If you have a low tolerance for any goo, psychiatry or neurology might be up your alley. If you can take any fluid being sprayed at you at high velocity, surgery may be an excellent specialty for you.

    Then there is the general opinion among the goo-heavy specialties that you should avoid the goo you dislike the most. For instance, if snot is bothersome, avoid pulmonary specialties and pediatrics. If it’s urine, maybe you shouldn’t go into urology (or if you don’t want to stare at genitalia all day). If you don’t mind blood but don’t like any of the stinky stuff, maybe neurosurgery is the right match. It’s all about balancing your goo exposure.

    If you don’t want to get divorced during residency, maybe read this paper. The surprising result? Psychiatry is the worst at a 50% cumulative divorce rate followed by surgery at 33%, and most other medical specialties between 22-30%. I guess psychiatrists drive their spouses nuts when they bring their work home.

    There is the Myers-Briggs guide to specialties which is only useful if you’re the type of person that likes astrology or other advice based on vague, general descriptions of people coached in psuedoscientific drivel. There is a lot of study of personality traits specific to different specialties, a review of the subject concludes that for the most part medical students tend to be too homogeneous for the blunt-instrument personality tests to distinguish something so specific as an ideal career choice and there is more variation of personalities within a given field than between fields.

    So, using these highly-scientific and time-tested methodologies, which kind of medicine would you like to practice? Which do you think I chose?

  • Allergies of the first kind—type I hypersensitivity explained in context

    If you have kids you have probably been exposed to the idea that more kids have food allergies these days. Well, the data seem to bear this out. There are several hypotheses about why this is so, but not a lot of data. Rather than engage in speculation, I’d like to wade back into the dangerous waters of real science and tell you a little about allergies. Perhaps after you’ve read my grossly oversimplified explication, you’ll come up with your own science-based hypothesis to explain increased childhood food allergies.

    First, let’s talk about what isn’t going on. The Huffington Post, always a target-rich environment for woo-hunters, has a writer named Sloan Barnett. She is about as well-informed about health issues as Bill O’Reilly is about anger management. Two of her recent posts address child health, and both display a stunning level of ignorance. Her fetishization of “green” bears no relation to actual research on childhood health.

    An example of her ignorance?

    But what really stopped me in my tracks was that children with food allergies are two to four times as likely to have related conditions such as asthma or other allergies. And guess whose very own children have nut allergies AND asthma….

    Um, yeah, Sloane. That’s because food allergies, asthma, and related conditions are, er, related! Asthma, allergy, and atopy are all a type of immune dysfunction known generally as type I hypersensitivity. Its determinants are partly genetic, partly environmental.

    Despite many studies, no one knows why this [increase in allergy] is happening. Here’s what I know. My third child, who was raised in a non-toxic home, eating only organic formula and food, recently tested allergy free. Look, I can’t be certain that our new lifestyle is the reason this baby is allergy free, but it sure does make you think.

    Actually, one of the most popular theories in scientific circles is the “hygiene hypothesis” which roughly states that our cleaner and more sterile environment exposes our kids to allergens later. If they had been exposed earlier, their immune systems may have developed a tolerance for common allergens. This hypothesis is based on observational studies that kids raised with pets, on farms and other “dirty” places have lower rates of environmental allergies.

    Still, we don’t know why we have an increase in childhood allergies, and clearly, neither does Sloane. Her evidence is based on what she’s heard and her own experiences, which is worth bubkes.

    Alright, let’s get to a little actual science.
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  • Antibiotic-associated colitis—a difficile problem

    It’s that time of year again—the time of year when everyone gets the sniffles, and everyone wants an antibiotic. Even folks who know better, who know intellectually that an antibiotic isn’t going to fix their viral illness still harbor a strong suspicion that it just might help—and it couldn’t hurt, right?

    Well, I’ve got two words for ya’ll: eat shit.

    No, I don’t mean that as an insult, I mean it quite literally. But you’ll have to keep reading to see what I’m talking about.

    Many readers are aware of the problem of antimicrobial resistance—the phenomenon whereby bacterial diseases become resistant to antibiotics, a problem exacerbated by the profligate and inappropriate use of these agents. Another serious complication of antibiotic therapy is antibiotic-associated colitis (which also goes by the names “pseudomembranous colitis”, “Clostrium difficle colitis“, or simply “C diff colitis”.) This one is nasty. As diseases go, this is one you really, really don’t want. Really. Think I’m kidding? I’ve got two more words for you: toxic megacolon.

    OK, let’s get down to details.
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  • Why good medicine requires materialism

    I don’t like to repost, but Steve Novella has some great pieces up right now, and this is directly related. –PalMD

    s I’ve clearly demonstrated in earlier posts, I’m no philosopher. But I am a doctor, and, I believe, a good one at that, and I find some of this talk about “non-materialist” perspectives in science to be frankly disturbing, and not a little dangerous.
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  • Man-cow hybrids: has the time finally come?

    In a little over a week, Michigan voters will be asked to vote on Proposal 2. The proposal is very simple. It is a constitutional amendment that makes Michigan a less hostile place for human embryonic stem cell (HESC) research. It forbids state or local government from passing laws that are more restrictive than federal law. Here’s how it will appear on the ballot:

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  • My irony meter just exploded

    How stupid do you have to be for Jenny McCarthy to legitimately toss the epithet back at you?

    This question may seem unanswerable, but in this case, McCarthy may have gotten it half right regarding Dennis Leary. The headline at MSNBC delcares: McCarthy calls Leary ‘obviously stupid’

    I don’t know much about Leary, but like many comedians he has said something that he will probably regret and move on. In attempting to be funny, Leary scored an epic fail (you can tell it’s an epic fail because Jenny did get it half right):

    “There is a huge boom in autism right now because inattentive mothers and competitive dads want an explanation for why their dumb-ass kids can’t compete academically, so they throw money into the happy laps of shrinks . . . to get back diagnoses that help explain away the deficiencies of their junior morons. I don’t give a [bleep] what these crackerjack whack jobs tell you – yer kid is NOT autistic. He’s just stupid. Or lazy. Or both.”

    OK, in or out of context, not very funny. Autism is a serious neuro-developmental disorder, and his unfunny pseudo-Scientological riff doesn’t help advance the cause of autism diagnosis and treatment. So Jenny is right (if somewhat non-specific and unsophisticated) in calling him “stupid”. But Leary is up against some serious competition, and when it comes to bringing the stupid, no one does it quite like Jenny McCarthy.

    “My fight isn’t with Denis Leary, my fight is with the government — a bigger fish to fry. So I’m still gonna work on the vaccines and I’m still working on pediatricians and Denis Leary can go hopefully be more educated by every mother that stops him from this day forward to give him a piece of their mind,” she said.

    I’d argue that Leary’s comments are an opportunity for public education. To minimize a public figure’s idiotic comments about autism in favor of a fight against “the government and vaccines”, is a level of stupid unique to Jenny. The only conspiracy in Jenny’s world is her own conspiracy of ignorance. He’s is a conspiracy that prepares fertile soil for other real conspiracies—those by quacks and charlatans who give parents false hope, steal their money, harm their children, and distract from real autism research.

    Brava, maestra!

  • So what's the good news?

    This thread needed to be moved up for obvious reasons. Have at it. –PalMD

    I’ve been writing quite a bit about “questionable” illnesses, shameless quacks and the like, but there are reasons that people seek out odd diagnoses and cult doctors. They feel crappy, and they haven’t yet found someone who can make them feel less crappy.

    Of course, some people will never feel OK. That’s just human nature. But almost everyone can be helped to feel better in one way or another. What are some of the ways physicians approach difficult-to-treat patients?

    First of all, there are many syndromes that involve unexplainable pain. These include fibromyalgia, irritable bowel syndrome, interstitial cystitis, and others. These diseases are painful, but have no clear pathologic correlate, meaning all the tests in the world don’t clearly explain why the person is in pain. This doesn’t mean the patient is “faking it”—they really do feel miserable. We just don’t understand the cause. The other thing about these syndromes is that they are not life or limb threatening. Unlike, say, heart disease, they can hurt without causing physical damage to the body.

    Some patients have clear “somatization” or “psychosomatic” disorders…
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  • Why should I trust you?

    On call one night as a medical student, I was presenting a case to my intern. As I recounted the patient’s ER course, the intern stopped me and said, “Pal — trust no one.”

    That sounded a little harsh to me, but the intern was nice enough to explain further.

    “Look, you’re going to be taking calls from doctors and nurses the rest of your career. They are going to give you information about a patient, but it’s you who will be responsible for everything that goes right and wrong. Do you want to hang yourself on someone else’s evaluation?”

    As any internist knows, there is a perpetual tension between ER and internal medicine docs. ER docs need to save lives and move meat. The snapshot the ER doc gets is sometimes inconsistent with the bigger picture the internist sees, leading to some conflict. It’s inevitable, really, that how the patient looks in the ER will differ from how they are up on the floor several hours later. And this is what my intern was conveying to me.

    Patients will often complain about the parade of students, interns, residents, and attendings who seem to ask the same set of questions, but this was my intern’s point: things change, stories change, clinical facts change, and you better make sure the facts you report are the facts you verified.

    (As an aside, it’s a not infrequent occurrence that a patient’s story will change significantly with the length of the white coat. The indigestion the student hears about becomes the crushing sub-sternal chest pain the attending rushes to the cath lab.)

    I also remind patients that they don’t know which one of us might be called to their bedside in the middle of the night, so it’s best tolerate us all.

    Anyway, this is my long-winded way of getting to the issue of trust. There are ER doctors who I’ve worked with for years and I know pretty well. I know their quirks, and I know that what they tell me is how it is (at that particular moment).

    If I get an ER call from someone I don’t know, I will listen politely, but I’m probably going to see that patient first and re-check everything myself.

    So “trust no one” isn’t precisely the dictum, but it’s a start. Clearly level of trust is influenced by many different factors.

    At January’s ScienceOnline09 conference, Terra Sig’s Abel Pharmboy and I will be hosting a session on blogging and anonymity. It’s a topic particularly important to us as bloggers of medical science. A number of months ago, I “unmasked” myself and never really explained to anyone why. Pseudonyms are a big part of blog culture, and I preferred to keep mine while no longer guarding my real identity (for various reasons).

    I would argue that in the blogosphere, there are three levels of identity: real name identity, pseudonymity, and anonymity. Real name identity is still not the “real person”. People write and behave differently online. Pseudonymity (my particular choice) involves using a pseudonym, but having one’s true name generally known or available. Anonymity is just that—the attempt to keep your real life identity completely secret. Each of these levels has different implications on both how the writer behaves and how the reader perceives.

    Abel has brought the issue of trust forward—both the reader’s trust of the blogger, and the blogger’s trust in the reader. At our session (which we’d love to have you at, but will probably blog about, or better yet, maybe we’ll live blog it and take questions) I’m sure we’ll address lots of these issues, but we’d like to hear from denizens of the blogosphere. Abel’s question was, “do you trust me?” My question to you is, “Do you consider blogger identity when reading, and if so how? And do you find there to be a difference in the three levels of identity?”

    Or of course, ignore my question, and say whatever you wish.

  • Tissue is the issue–revised version

    NB: images in this post are thought to be in the public domain, but were not well labeled, so if you feel they have been posted without proper attribution, please email me or leave a comment. Thanks. Also, this is a revision of a post from yesterday which I’ve pulled secondary to ethical concerns. I’ve deleted the comments so we can start out fresh. –PalMD

    I can’t seem to get this whole “morgellons” thing out of my head (which gives me something in common with the sufferers). Lots of the “literature” on morgellons focuses on the “fibers” which supposedly infest these people. If you google it, you can get pictures galore of these fibers. The advocacy websites are also full of stories of “fiber analysis” from law enforcement. I’m not much for crime lab analyses when it comes to human pathology. Show me the tissue!

    If morgellons were a disease as such, it would cause pathologic changes in the tissue affected. These should be visible on both a gross an microscopic level. Let me show you what I mean.

    A young woman came to see me a few years back with a rash. She had rashes in the past—poison ivy, mosquito bites, chicken pox—but this one was different. It was all over her legs, many of the bumps were raised, and it was spreading quickly.

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