by
Jim Wood
I
am a patient. I used to be a regular
human being, but that was a long time ago.
Back in the 1980s, as a result of a routine office visit and blood work,
I was found to have slightly elevated blood pressure and blood sugar. Nothing to worry about, merely in the upper
range of normal, but probably worth keeping an eye on in the future. Then, a few years later, I was diagnosed with
two conditions called prediabetes and
prehypertension, neither of which I
had ever heard of before; so I was put on a lifetime’s worth of
medication. A few years after that, I
was diagnosed with full-blown type 2 diabetes and essential (if mild)
hypertension. So my meds were augmented
and the dosages upped. By now I was a
definite patient, requiring frequent monitoring and more aggressive treatment.
Sphygmomanometer; Wikimedia Commons |
But
here’s the curious thing: my numbers (blood pressure and blood sugar) had not
become worse. In fact, they had improved
a bit, which presumably had something to do with the meds. Moreover, I had not developed any
symptoms. I did not have peripheral
neuropathy, I had never experienced a coma, my feet and kidneys were just
dandy, I had never had a stroke or any sign of heart disease. In fact, the only major health problem I had
turned out to be the result of one of the medications I was on, which actually
caused serious hypotension, at least
in me. The scrip was withdrawn and now
I’m fine. I remain a patient, but a
patient without a disease.
If
there was no deterioration in my physical condition, how did I go from having
minor not-quite-symptoms to having two life-threatening illnesses? The answer is simple: the magic trick was
performed by a series of Expert Medical Panels – well-known physicians and
epidemiologists who were aided by representatives from the pharmaceutical industry. These worthies decided on several occasions to
lower the threshold values used to diagnose hypertension and type 2
diabetes. Were these changes inspired by
new evidence that even mild elevations in blood pressure or blood sugar caused
serious disease and a greater risk of death?
No. They were inspired by a
longstanding commitment to “preventive medicine” – the well-intentioned idea
that we can intervene in people’s lives before they develop overt disease (i.e.
before they display real symptoms) and delay or prevent those diseases from
ever happening. I remember that, when I
was a callow youth, the idea of preventive medicine was fairly new and the public
reaction to it was overwhelmingly positive.
This was something that just plain made sense. And, in fact, some preventive measures worked
really well: don’t smoke, get some exercise, watch your diet, and get a bunch
of vaccinations. But other preventive
measures had effects that were more equivocal, improving people’s health only
at the margin and mostly turning a whole bunch of perfectly normal people into
patients.
Take
hypertension as an example. The
thresholds (both systolic and diastolic) for diagnosing hypertension were
reduced in 1997 as a result of the Sixth Report of the Joint National Committee
on Detection, Evaluation, and Treatment of High Blood Pressure, which appeared
in Archives of Internal Medicine. It has been estimated that this change
increased the number of people in the U.S. diagnosed each year with the disease
by about 13 million. (This figure comes
from the excellent book by Dr. Gilbert Welch et al., Overdiagnosed, Beacon 2011.)
That’s a lot of new customers, er, patients. Did it help any of those new patients? Well, some no doubt, but while the number of
people being treated for hypertension skyrocketed, the mortality rate from
causes of death associated with hypertension changed pretty much not at
all. What the change in diagnostic
criteria did was greatly increase the number of normal people who have to be
treated without benefit in order to increase the chance that you help just one
person who really needs it (given that you can’t empirically distinguish the
normals from the ones needing help). In
the past, when the diagnostic criteria were set high, nearly everyone who was
diagnosed and treated probably benefitted to some degree (if they didn’t die
from some other cause or indeed from hypertension meds first). Using the current standards, however, a large
fraction, perhaps a majority, of people being diagnosed and treated probably
have no underlying disease and are unlikely to develop it in the future even
without treatment. Am I one of those
people? I have no way of knowing, short
of going off all my medications and waiting to see if I die in short
order. Do I want to do that? Not really (being both a moral and a physical
coward). Do I suspect that I may be
receiving treatment that either is unnecessary or at best will have only
trivial benefits? Well, yes.
The
basic underlying epistemological questions here are (1) can you ever make valid
predictions about future disease risks; (2) how can you turn continuous
biological variation in, say, blood pressure into a simple, dichotomous
(yes/no) criterion for clinical decision-making; and (3) how can you capture
inter-individual physiological variation with a single set of numbers? The answers are: (1) no, (2) you can’t – at
least not without injecting a big dose of arbitrariness and error into the
process – and (3) you can’t, period. In
assessing the value of some diagnostic criterion like a blood pressure cut-off,
we speak of sensitivity and specificity. Sensitivity is the probability that your
criterion correctly identifies everyone with the condition of interest,
including people who are not yet displaying clear-cut pathologies (one minus
the probability of a false negative).
Specificity is the probability of correctly diagnosing only the people with the condition of
interest and not those with some other condition or no condition at all (one
minus the probability of a false positive).
Both sensitivity and specificity are virtues, and you’d like to design
your diagnostic methods so as to maximize both of them simultaneously. But, generally speaking, you can’t because
they compete with each other. To
guarantee that you catch all criminals, jail everyone (a rather Javert-like
solution, I admit). By the same token,
to guarantee that you treat all cases or potential cases of a disease, diagnose
and treat everyone. Sure, most people
won’t actually have the specific disease you’re trying to diagnose (the
specificity will be as low as it could ever get), but that’s the price you pay
for perfect sensitivity. Although what
I’ve just described is, of course, a gross exaggeration of current clinical
practice, there’s no doubt that things have been moving in that general
direction. The whole goal of preventive
care is to maximize sensitivity (in this case the ability to detect a disease
even when there’s no overt sign of it) at the expense of specificity in order
to “improve” prediction. But that’s a
mug’s game because a prediction with a high false positive rate is not a good
prediction.
Is
all this the result of an evil conspiracy of greedy drug manufacturers and
health-care providers? I honestly don’t
know (even if I sometimes have my suspicions).
I think it’s entirely possible that it’s simply the result of
misdirected good intentions and a fervent if wrongheaded faith in preventive
medicine. I genuinely like and respect
my primary care physician, who assures me that I’m going to die if I go off my
meds. (I’m pretty sure I’m going to die
anyway, but that’s another story.) I
truly think she has my best interests at heart.
But do I think she’s bought into a mind-set that seriously needs to be
rethought? Absolutely. Do I enjoy her treating me like a patient in
the absence of any discernible disease? Not
a bit. Do I have the courage to tell her
so? See the comment about moral
cowardice above.
There
are many reasons that unnecessary patienthood is annoying and costly (to me,
never mind the general public) and maybe sometimes even dangerous. As already noted, I’ve had a non-trivial
medical emergency (which landed me in the hospital) caused by one of my medications. And I have to do “co-pays” for all my exams,
treatments, and prescriptions – even though, by U.S. standards, I’m
ridiculously well-insured. And God knows
I’ve experienced my fair share of annoyance scheduling frequent physical exams
and blood tests and taking the time to refill my many prescriptions. But my real objection to being a patient runs
deeper than any of that – being treated like a patient is infantilizing. I bristle at that subtle hint of moral disapproval
when my doctor tells me my numbers have “worsened” (often within the range of
measurement error). I bristle even more at
that slight tone of “What a good boy!” that accompanies any “improvement” in my
numbers. I was treated like a child for
the first several years of my life, and I got thoroughly fed up with it. Why is it happening to me again?
There
are those in our society who need health care and are not getting it. I am not one of them. If we want to improve the health of the U.S.
population in general, the single best thing we can do is eliminate disparities
in access to health care. My being
treated is not furthering that goal at all, although it is increasing the costs
of health care for everyone. Let’s face
it: the lovely idea of preventive medicine comes in a poisoned chalice.
9 comments:
It's ridiculous how we try to handle this, and after my most recent visit to the doctor, and his frightening diagnosis, I have changed my view.
Doc told me I had 'premortis sapiens'. "What the ... is that?" I asked. It's the multitudinous progress towards inevitable death of a wise (hence sapiens) organism.
The solution is this: For every known cause of disease and death, there is a risk. For most of them there are at least some treatments. So, with the pharmaceutical industry's approval, my doc has now put me on a coctail of meds for all of the causes, with dose proportional to estimated risk.
That approach should settle all these issues for once and all.
And, hell, then there was more! I went to my doctor to be poked and prodded because otherwise I wouldn't be able to get Penn State's affordable health care insurance. I had my phenome typed, I had my genome typed, I had my PET, CAT, and MRI reports, I had my nutrition evaluated, and I don't even smoke (any longer).
Then, damn! I was leaving the doctor's office, feeling safe and satisfied as I wended my way to Rite-Aid with my fat sheath of prescription orders to treat my premortis, when I saw this story:
http://www.bbc.co.uk/news/technology-23709009
Now, it turns out that using _Facebook_ is bad for your health! Double damn!
What do we need to do next??
Jim: I resemble your remarks, thank you.
The BP goalpost-shifting was briefly a topic of controversy at the turn of the century. For views harmonising with yours, see:
Port et al. Systolic blood pressure and mortality. Lancet (2000) 355:175-180.
www.ncbi.nlm.nih.gov/pubmed/10675116?dopt=Abstract
Port et al. There is a non-linear relationship between mortality and blood pressure. Eur Heart J, (2000) 21:1635-1638.
www.ncbi.nlm.nih.gov/pubmed/11032685?dopt=Abstract
There is also the truly cogent but overlooked point that if BP really is predictive and you lower it, you very directly risk surviving a quick cardiovascular demise and increasing risk of a slow and nastier one from cancer and other degenerative disorders. Public health policy nor medicine have really dealt with such issues; they are too inconvenient to think about.
Congratulations, Ken. You've achieved immortality. Oh, wait, some day you'll get struck by lightening or run over by a Mack truck. Best never to leave your house. Wait, then you'll be exposed to asbestos or radon and...
Your comment raises the important issue of competing causes of death: if one thing don't getcha, another thing will. Competing causes (and especially competing and interacting causes) are, as you suggest, difficult to think about, let alone analyze using real data. But basically they mean that if you were to completely eliminate a disease that currently causes, say, 40 percent of all deaths in a population, that would achieve nothing even close to a 40 percent reduction in mortality. People would just die of something else.
Thanks, Anonymous. I look forward to reading them.
Yes, and then there's the Catch 23 that being immortal will be very boring perhaps and depressing. So that means some more anticipatory meds.
Untreated hypertension and diabetes were associated with Alzheimer's disease. Based on that I'd say people with increased genetic risk for Alzheimer's Disease should be treated more aggressively for even slight elevation in blood pressure and blood sugar. Those without such risk - less so.
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