On Sat, 5 Feb 2000, Robin Hanson wrote:
> I wrote:
>
> > I think you can attribute modern health to three things: (1) sanitation,
> > (2) antibiotics, and (3) vaccines. ... A fourth factor is the simple
> > understanding of germ theory and communicability and getting medical
> > practicioners to follow practices that minimized transmission. But these
> > factors combined are what has extended average longevity from
> > ~30-40 years to ~75 years.
> >
> This is completely wrong. I'm lecturing my health economics
> class on this topic this last week and this upcoming week, and
> have been reading up on it for fun & preparation.
> (see Sources for: http://hanson.gmu.edu/EC496S00.html )
>
Robin, I've looked at your page and unfortunately those sources don't
seem to be in my library. However, the strength of your opinion made
me start reading through some of sources I do have, and is causing
me to modify the "standard opinion" one gets in microbiology classes
(which do of course tend to be oriented towards PreMeds).
Citing, John Cairns, MD (Harvard School of Public Health), from
"Matters of Life and Death":
"It was aobut then, at the end of the eighteenth century or early in the
nineteeth century, that life expectancy started to climb upward. For
those lucky enough not to be in large cities, life expectancy had been
roughly forty for hundreds or even thousands of years (except, of course,
in times of famine and pestilence). Over the next 150 years, however,
the industrial nations of the world were to see average life expectancy
move up to 75 and beyond". [p. 15]
"The first half of the nineteenth century was therefore a time for
assembling statistics, arguing about causes, and preparing for a reform
in public health.
The main causes of death were certain infectious diseases that the
industrialized nations have now almost completely eradicated (table 1.2)."
[p. 22]
"If therefore we look back over the history of this one disease (diphtheria),
we would have to say it was largely conquered by prevention--first as part
of the general reduction in mortality from many diseases at the end of the
nineteenth centuury (perhaps because of improvements in nutrition),
somewhat later as the result of direct efforts to restrict the spread of
disease, and finally as the result of a specific program of immunization.
Advances in the treatment of diphtheria (as opposed to its prevention),
in particular the discovery of antibiotics, have had only a minor effect
on mortality." [p. 29]
"... we should remember that half of the reduction in mortality from
diptheria had already been achieved before the technological solution
was available." [p. 31]
Based on Cairns comments, I would change my previous statement
that modern longevity is due to: (1) Education; (2) Nutrition;
(3) Sanitation; (4) Vaccines and (5) Antibiotics. His discussions
regarding the health and infant mortality rates in modern countries
would seem to confirm that public knowledge (e.g. prenatal nutrition)
and government health regulations (e.g. for clean drinking water) probably
contribute much more to longevity than do medical practices.
However, when I originally cited antibiotics, I was mainly thinking of
rural farmers having accidents that get infected and require antibiotic
treatment (or alternatively vaccinations). Of couse since more
and more of the population is in the cities, this has a relatively
low impact on the overall mortality rate.
But considering his Table 1.2:
=========================================================
Death Rates (per million) in England and Wales
Deaths due to Infectious Diseases 1848-54 1971
Tuberculosis 2901 13
Bronchitis, pneumonia, influenza 2239 603(a)
Scarlet fever and diphtheria 1016 0
Other airborne diseases 1103 3
Cholera and dysentery 1819 33(b)
Other food & water borne diseases 1743 2
Total for all infectious diseases 12965 714
Total for all non-infectious diseases 8891 4670
(a) Predominantly pneumonia in the very old.
(b) Predominantly infantile diarrhoea.
Source: T. McKeown, "The Role of Medicine, Dream, Mirage, or Nemesis", 1976
===========================================================
I don't think you can discount sanitation and vaccines entirely.
> Medicine overall seems to have very little effect on health. This is the
> usual answer from statistical analyses, and from the few controlled
> experiments we have. The mortality rates of most diseases treated by
> antibiotics didn't change noticably upon the introduction of that treatment.
> I don't think we have controlled experiments regarding sanitation, but the
> statistical analyses we do have don't show any effect of sanitation on health.
I attribute the reduction in Cholera deaths & other food & water borne
diseases directly to sanitation. Tuberculosis in large part seems to
be due to a reduction in crowding in cities, generally higher economic
levels (witness the increase in TB in Russia with the declining economic
conditions), changes in building heating, etc.
>
> I'd guess that Medicine of all forms probably contributes less than 1 year
> to that 40 year increase in lifespan.
If by medicine, you mean antibiotics, I would likely agree. If you include
vaccinations I think I would need some stronger evidence.
> Since sanitation also doesn't seem that important, it is a big puzzle
> why exactly lifespan has increased so.
Again, we may "split" hairs as to exactly what we call sanitation.
Cairns cites the availability of washable cotten clothes allowing
people to actually bathe more frequently.
Sanitary practices (or medical knowledge) are also responsible for
the huge reduction in female mortality following birth in the mid-late
19th and early 20th centuries as physicians learned to wash their
hands between deliveries. It is certainly true that poor hygene
by physicians and irrational practices such as blood-letting probably
contributed to the high mortality rate in cities.
Nutrition (esp. the variety of foods available and/or refrigeration)
may have also played important roles. I can't believe that you get
the MDR for vitamins or minerals (esp. Zn for the immune system) on
a diet of potatoes in the winter.
> It is also a puzzle why the US spends 14% of GDP on medicine.
Cairns alludes to the # of doctors...
"And market forces will lead to an overabundance of doctors, becuase
there is almost no limit to the opportunities for lucrative medical
practice in countries with a rich aging population. (Incidentally,
there does not seem to be much benefit in going above about 10 doctors
per 10,000 population, because an extension of the analysis to other
groups showed that no one, except possibly the very old, benefits
from the presense of a large number of doctors.)
If this is true, the best thing the government could do is reduce
subsidies to medical schools for educating physicians and increase
support for "bioengineering" so we can make increased progress on
designer organs, artificial genomes, etc. (those causes of death
that standard medical practice will be unable to impact).
Robert
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