Anecdotal evidence. An oxymoron? Or a valid approach to understanding data?
The problem is there are different kinds of anecdotes, used for different purposes, but the purpose of anecdotes is rarely if ever defined explicitly. Anecdotes are used for one purpose by one speaker/writer but interpreted in a different context by the listener/reader. People love anecdotes, especially if the anecdotes are about them or their beliefs. Anecdotes are how patients transmit the particulars of their disease to their health care providers. The medical history, as taken from the patient, is an extended anecdote, from which the particulars of the disease have to be extracted. Anecdotes are how physicians explain disease and treatments. Anecdotes are a tool with which teachers instruct their students. Anecdotes are how CAM proponents validate their particular system, and how skeptics invalidate them.
Anecdotes are useful tools for presenting yourself and your ideas. The convention season is over and is was striking how the candidates attempted to win over voters with anecdotes about their lives rather than the particulars of their policies. Using variations of ‘anecdote’ as a pubmed search term yields little of substance. The predominant theme on medline is to contrast anecdotes with evidence, always to the detriment of anecdotes. Anecdotes have power to influence far greater than evidence.
On The Skeptics Guide to the Universe #165 there was an interview with Ben Goldacre, who noted that there was the popular misbelief that the MMR vaccine was a cause of autism. The belief waned not when the voluminous data on the safety and lack of association with autism and the MMR was released, but when it was discovered that the primary proponent of the MMR/autism link received large sums of money to testify about that MMR/autism link. It was the anecdote about his conflict of interest that invalidated the idea, not the science.
“If you’ve done six impossible things this morning, why not round it off with breakfast at Milliway’s—the Restaurant at the End of the Universe!”–Douglas Adams
I recently finished reading the book “The Joy of Pi” by David Blatner. There is a chapter about the concept of squaring a circle, also called the quadrature of a circle. The idea is that, with just a ruler and a compass, you construct a square of equal area to a given circle.
It turns out it cannot be done. It is, in this iteration of the multiverse, impossible. Not difficult, or implausible or really hard. Impossible. You cannot square a circle in a finite number of steps given the conditions of using only a ruler and a compass.
That it is impossible does not prevent people from trying. Individuals do derive solutions to squaring the circle, and sometimes the derivation is erroneous, and sometimes they have a solution that requires a new value for pi.
Pi is the ratio of the circumference of a circle to its diameter. Take the circumference of a circle, divide it by its diameter and get the endless, or transcendental, number 3.141592654….(1) That number is part of the fabric of this universe. It is a fundamental part of how life, the universe, and everything is put together (2). It is a curious psychopathology that some people feel that all of known mathematics is wrong, and that they have a solution to an impossible problem and that they have discovered the hither to unknown, one true value of pi as a result.
“The graveyards are full of (unvaccinated) men.” Charles de Gaulle, modified by the author.
We live longer than anytime in history. Our long lives are due in large part to good nutrition, sanitation, and vaccines.
There have been numerous posts here and elsewhere about the vaccine deniers, primarily focused around the modern myth that vaccines cause autism.
That is not the topic of this post. Instead, I am going to take a brief tour of the childhood vaccines and review the morbidity and mortality caused by vaccine preventable diseases and the efficacy of the vaccines in preventing these diseases. With the brouhaha surrounding vaccines it is beneficial to step back and contemplate the death and misery that the vaccine preventable disease have caused and continue to cause.
In the interests of full disclosure, I am an Infectious Disease doctor. I make a living from treating diagnosing and treating infections. I don’t make dime one if people do not get infected, so I am against any and all vaccines as they cut into my bottom line (2).
Do not trust the cheering, for those persons would shout as much if you or I were going to be hanged.”
~ Oliver Cromwell
In the blogosphere, the proponents of chiropractic often quote the following paper, with the abstract:
Risk of Vertebrobasilar Stroke and Chiropractic Care
Results of a Population-Based Case-Control and Case-Crossover Study
Spine. 2008 Feb 15;33(4 Suppl):S176-83.
by Cassidy JD, Boyle E, Côté P, He Y, Hogg-Johnson S, Silver FL, Bondy SJ.
Why be different? Here is the abstract.
STUDY DESIGN: Population-based, case-control and case-crossover study. OBJECTIVE: To investigate associations between chiropractic visits and vertebrobasilar artery (VBA) stroke and to contrast this with primary care physician (PCP) visits and VBA stroke.
SUMMARY OF BACKGROUND DATA: Chiropractic care is popular for neck pain and headache, but may increase the risk for VBA dissection and stroke. Neck pain and headache are common symptoms of VBA dissection, which commonly precedes VBA stroke.
METHODS: Cases included eligible incident VBA strokes admitted to Ontario hospitals from April 1, 1993 to March 31, 2002. Four controls were age and gender matched to each case. Case and control exposures to chiropractors and PCPs were determined from health billing records in the year before the stroke date. In the case-crossover analysis, cases acted as their own controls.
RESULTS: There were 818 VBA strokes hospitalized in a population of more than 100 million person-years. In those aged <45 years, cases were about three times more likely to see a chiropractor or a PCP before their stroke than controls. Results were similar in the case control and case crossover analyses. There was no increased association between chiropractic visits and VBA stroke in those older than 45 years. Positive associations were found between PCP visits and VBA stroke in all age groups. Practitioner visits billed for headache and neck complaints were highly associated with subsequent VBA stroke.
CONCLUSION: VBA stroke is a very rare event in the population. The increased risks of VBA stroke associated with chiropractic and PCP visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke. We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care.
King Arthur: Now stand aside, worthy adversary.
Black Knight: ‘Tis but a scratch.
King Arthur: A scratch? Your arm’s off.
Black Knight: No it isn’t.
King Arthur: What’s that, then?
Black Knight: [after a pause] I’ve had worse.
King Arthur: You liar.
Black Knight: Come on ya pansy.King Arthur: [after Arthur's cut off both of the Black Knight's arms] Look, you stupid Bastard. You’ve got no arms left.
Black Knight: Yes I have.
King Arthur: Look!
Black Knight: It’s just a flesh wound.Monty Python and the Holy Grail
I am, I think, in a minority on this blog, in that I do not think there is a placebo effect. Period. None. Zip. Zero. Nada. Zilch.
For analysis purposes, I divide the lack of placebo effect into outcomes that do not occur with objective measurement and those that do not occur with subjective measurement.
Why the dichotomy? Those studies where there have been an active treatment, a placebo treatment and an observation group, have demonstrated no difference between observation and placebo (1). To summarize from the conclusion of the compelling NEJM review:
“We found little evidence in general that placebos had powerful clinical effects. Although placebos had no significant effects on objective or binary outcomes, they had possible small benefits in studies with continuous subjective outcomes and for the treatment of pain. Outside the setting of clinical trials, there is no justification for the use of placebos.”
I have a friend who’s an artist and he’s some times taken a view which I don’t agree with very well. He’ll hold up a flower and say, “look how beautiful it is,” and I’ll agree, I think. And he says, “you see, I as an artist can see how beautiful this is, but you as a scientist, oh, take this all apart and it becomes a dull thing.” And I think he’s kind of nutty.First of all, the beauty that he sees is available to other people and to me, too, I believe, although I might not be quite as refined aesthetically as he is. But I can appreciate the beauty of a flower.
At the same time, I see much more about the flower that he sees. I could imagine the cells in there, the complicated actions inside which also have a beauty. I mean, it’s not just beauty at this dimension of one centimeter: there is also beauty at a smaller dimension, the inner structure…also the processes.
The fact that the colors in the flower are evolved in order to attract insects to pollinate it is interesting – it means that insects can see the color.
It adds a question – does this aesthetic sense also exist in the lower forms that are…why is it aesthetic, all kinds of interesting questions which a science knowledge only adds to the excitement and mystery and the awe of a flower.
It only adds. I don’t understand how it subtracts.
Taken from Richard Feynman: What Do You Care What Other People Think?
Stein: When we just saw that man, I think it was Mr. [PZ] Myers, talking about how great scientists were, I was thinking to myself the last time any of my relatives saw scientists telling them what to do they were telling them to go to the showers to get gassed.Stein (speaking about the Holocaust): …that was horrifying beyond words, and that’s where science — in my opinion, this is just an opinion — that’s where science leads you.Crouch: That’s right.
Stein: … Love of God and compassion and empathy leads you to a very glorious place, and science leads you to killing people.
I am a full time Infectious Disease physician. In the short hand of the medical field, I am an ID doc. Recently, saying I do ID is kind of like having last name like Himmler. No relation, but a vague discomfiture that I might be misrecognized as something else.
My ID, the real ID, along with medicine, is a branch of science (I always hear Mangus Pyke in the Thomas Dolby song when I type the word) with a long history, of, well, saving lives. Lots of lives. Millions and millions of lives. And relieving suffering. The simplest of things have been responsible for the long and reasonably healthy lives we get to have here in the industrialized world.
The Science-Based Medicine Blog deals with what Merlin Mann refers to as first world problems. The fine points of botanicals and prostatism or whether the placebo effect is the cause of the response to acupuncture. Interesting though these topics can be to some, when it comes to the overall health of most of us in the first world the main triumphs of science (Or is Ducks Breath I hear? “I have a masters degree in Science”) occurred over a century or two ago. The science of 200 years ago, by the standards of today, was simple, with simple results, but lead to remarkable advances in longevity and health.
MIRACLE MAX: See, there’s a big difference between mostly dead, and all dead. Now, mostly dead: he’s slightly alive. All dead, well, with all dead, there’s usually only one thing that you can do.
INIGO: What’s that?
MIRACLE MAX: Go through his clothes and look for loose change.
— The Princess Bride
Can you trust anyone when they purport to tell you what the medical literature says? No. As an example we will use the issue of near death experiences, or NDE’s.
We will avoid the obvious paradox in this entry, sort of the ‘everything I say is a lie paradox’ that will cause computers in the Federation to shut down.
Why am I going to comment on this issue? Well, this months Skeptic has a back and forth between Michael Shermer and Deepak Chopra about life after death.
No. I am not going to comment on whether there is life after death. I am more interested in life during life, thank you very much. I’ll let the afterlife take care of itself.
But in their point counterpoint, they both refer to a Lancet article about NDE’s and it then begs the question:
Does anyone actually read or understand the literature they quote ?
CUSTOMER: Here’s one — nine pence.
DEAD PERSON: I’m not dead!
CUSTOMER: Nothing — here’s your nine pence.
DEAD PERSON: I’m not dead!
MORTICIAN: Here — he says he’s not dead!
CUSTOMER: Yes, he is.
DEAD PERSON: I’m not!
MORTICIAN: He isn’t.
CUSTOMER: Well, he will be soon, he’s very ill.
DEAD PERSON: I’m getting better!
CUSTOMER: No, you’re not — you’ll be stone dead in a moment.
Monty Python and the Holy Grail
For some unexplained reason, people at work like to tell me of the positive interactions they have had with acupuncturists and chiropractors and others of that ilk. I must have a friendly face, but I keep checking my back for a “CAM me” sign.
One of the oncology nurses was telling me how she has chronic neck pain, and that she was skeptical about acupuncture, and would never recommend these therapies for one of her cancer patients, but she went to an acupuncturist, and by gosh and by golly if her pain wasn’t better, what do you think of that Mr. Skeptic?
Call me Dr. Skeptic, I replied. Show some respect for the dead.
It does make for an awkward conversation.
I cannot deny that she isn’t better. How can I argue that she doesn’t have decreased pain? She is the one who hurts and is the one who can best judge the degree of her discomfort.
“Nope. You are not better. Sorry. Wrong. You are still in the same amount of pain you were before.”
It is an untenable position.
It’s a case of mind over matter. I have no mind but it doesn’t seem to matter.
— George Burns
I should be working on my taxes. Instead, I’ll dwell on the other, more pleasant, inevitability.
Its been a bad couple of months for death. Everyone dies, and people often die of infection, but the flu season has been busy and with the MRSA lurking in the community, I have seen too many young die who should have otherwise survived their influenza.
I spend most of my professional day working in an acute care hospital, and most people in the hospital die of something. They die when their heart or lungs or liver or brain or some combination sustain more damage than can be compensated for. People live within fairly narrow operational parameters and when those parameters are exceeded for any length of time, they die. It is never a surprise when people die due to organ failure past the point of return or support. That is the cause of death in most of the patients I see.
Sometimes, and not very often, people die of nothing in particular. They just die. You get an autopsy, and there does not appear to be any single event that caused the death, nor does the sum of the underlying diseases seem to have lead to death. Usually it is the advanced elderly who just die. There reaches a point where the organism shuts down. I once had a patient die as I walked into the room on rounds. He looked at me and then died. He had many medical problems, but none that should have killed him, and his blood work on the day of death was normal and his autopsy had no clue as to why he died. Creepy. I like to have a definitive cause of death, but I do not always get one.