The favourable results of treatments can fade over time (the Decline Effect, see later post) for
many reasons. Often the
initial enthusiasm (bias) of the proponents is not replicated in later studies
(see previous
blog). But sometimes it can be shown that as the scientific validity of the studies improve, the effect decreases. This is because studies with better
scientific methods will (by definition) have less bias (causes of error) and
therefore the results will provide a better estimation of the truth.
Vertebroplasty (injecting osteoporotic vertebral fractures with cement) is a
recent (and controversial) case in point.
Tuesday, 29 May 2012
Saturday, 26 May 2012
Are you getting your money’s worth from surgery?
There is a common belief that if something costs more, it
must be better; that you get what you pay for. Recently, a friend of a friend
(this is not sounding very scientific, but hear me out) went to see two spine
surgeons about his neck pain. One surgeon advised against surgery. The other
recommended a neck fusion, to be done in the private hospital with an
out-of-pocket “gap” (the fee, above and beyond the health fund rebate) of
$10,000. He is now considering drawing on his retirement fund to pay for the
surgery. Considering that there are surgeons who will perform this operation
for no “gap”, is this worth it? Is the price a reflection of quality?
Wednesday, 23 May 2012
Appendicitis - is surgery necessary?
There is one thing (out of a list of many) that makes me
disappointed with a surgical trainee; it comes after they describe a new case
to me and offer their preferred surgical treatment. I then ask them for the
evidence supporting their recommendation. They say: “Well, I saw a guy do one
once.” This short statement says so much. Firstly, how we are influenced by
what we see, particularly when somebody considered to be
senior or authoritative does it. It also shows how readily we recommend
treatments without good knowledge of the outcomes of that treatment, or of the
alternatives. It is easier just to think: “If this guy did it, then it must be OK”.
This is why appendicectomy is so commonly done. Randomised
trials have told us that removing the appendix is not necessary on first
presentation, and it is associated with a worse long term outcome. Yet if you
present to any of my hospitals with suspected appendicitis, you are unlikely to
be leaving hospital without having your appendix removed.
Sunday, 20 May 2012
Stop attacking my heart
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The idea behind "revascularising" coronary arteries is very
appealing: “My blood vessels were blocked and the doctors unblocked them”. Like so many things addressed in my blog, this sounds good and seems hard to argue
with, unless you look at it scientifically and ask the right questions. ...
Thursday, 17 May 2012
Not such a great IDET
IDET (Intradiscal electrothermal therapy) fits perfectly
into the template for a successful placebo treatment described in my earlier
blog. It has everything: biological plausibility, high tech equipment, high
cost, conflicts of interest, great lab results, encouraging results from early
clinical studies, and no advantage over placebo...
Sunday, 13 May 2012
Cancer screening part 2: PSA for prostate cancer
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For the boys, prostate cancer screening is another case in
point. Screening is easy (just a blood test - a PSA) but like all screening programs
it is plagued by overdiagnosis, and the harms from treatment for this condition
are also quite significant (high rates of incontinence and erectile dysfunction).
Friday, 11 May 2012
Cancer screening part 1: mammography
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Cancer screening is a no brainer for most people, who think:
“why wouldn’t you do it?” It turns out that there are lots of reasons why you
wouldn’t do it; reasons that (of course) fall under the all too familiar
heading of Overestimating the Benefits and Underestimating the Harms. Time to
take a look at the risk-benefit balance.
Monday, 7 May 2012
RF: a harmful placebo
RF (Radio Frequency, or Radio Frequency Ablation) is used widely. The idea is that a
probe is inserted into the affected area which then emits a radio frequency
that “changes” (read: damages) the local tissues. It is used in the spine, the
shoulder, the wrist and even for liver tumours.
The story with this is so similar to my previous blogs that
many of you may be able to fill in the rest of this one for me. In fact, for
things like this I should develop a standard blog template to cut and paste in
the future. Something like this:
Saturday, 5 May 2012
Conflict of Interest, or Concordance of Interests.
My last blog on ultrasound and fracture healing brought up
the topic of authors with conflicts of interest. This is where the authors have
something to gain from publishing favourable results of medical therapies;
benefits that might include royalties, stock options, research funding and my
favourite: consultancy fees (this is fancy term for a relatively simple process whereby a
company gives money to a doctor, often large amounts and at regular intervals).
Sometimes the authors are direct employees of the company making the device or
drug in question. And sometimes these employees write the article for the
esteemed senior author to put his or her name to (ghost writing), thereby
giving the article authority.
Does ultrasound make bones heal? No.
The acronyms are getting bigger. LIPUS (Low Intensity Pulsed
Ultrasound) therapy is commonly used to heal fractures faster, or to get them
to heal when they have not. It is a machine that straps on to the limb and is
worn for minutes or hours each day, for a few weeks or months. Just like the
techniques in my recent posts, it costs several thousand dollars and people
assume that if it costs that much and is high-tech, it must be working. Lets
cut to the chase.
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