From: Robin Hanson (rhanson@gmu.edu)
Date: Fri Feb 11 2000 - 12:11:11 MST
I think I estimated here recently that medicine contributed about
one year to life expectancy over the last century or two. Let me
revise that to perhaps two years. I just read and considered:
Bunker, John P; Frazier, Howard S; Mosteller, Frederick (1994):
Improving health: Measure effects of medical care.
The Milbank Quarterly 72(2), 225-258.
This paper estimates the gains in US life expectancy from various
specific medical treatments, including immunization and screening.
Adding up all the items for which they estimate ranges gives a total
range of 4.9 to 5.5 years. Four items contribute the most by far, so
we can add it up this way:
Item Min Mos. Max Mos. Date Innovation
-----------------------------------------------------
smallpox 3 6 1800
diabetes 6 6 1920
diphtheria 10 10 1950
heart disease 14 14 >1950
all the rest 25 29 Misc.
---------------------------------------------
Total 59 66
I'll accept diabetes, but take issue with other three,
and take issue with just taking them literally.
On diptheria, Bunker et al credit medicine with the
entire fall since 1950, even though the US death rates
from it continued to fall after 1950 at about the same
rate they fell before 1950. The 1999 US Stat Abstract,
chart #1423 says deaths per 100,000 were:
1912 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980
139 139 82.1 54.1 30.8 11.8 14.1 3.8 1.2 0.5 0.1 0.2 0.1 <.05
On smallpox, the question is what the death rate would
be today had medicine never intervened. It seems natural
to suppose that smallpox death rates would have fallen
dramatically to near zero today just as did all the other
once deadly contagious diseases lacking substantial
medical prevention.
On heart disease, I just don't see that we have data tying
it to medicine.
Finally, these numbers assumes that people who die of a
disease were otherwise just as healthy as the people who did
not die of it. Since I don't believe this, I will knock off
1/3 from the total result. So I'll accept an estimate of
(2/3)*(27+10) months, or 22 months life expectancy gain from
medicine.
The paper also discusses contributions of medicine to quality
of life, rather than just mortality. So I'll note that an
analysis, http://papers.nber.org/papers/W6895, of quality-adjusted
life improvements 1970-1990 finds that >80% of the total
improvement is from lifespan changes, with <20% due to other
quality of life contributions.
Robin Hanson rhanson@gmu.edu http://hanson.gmu.edu
Asst. Prof. Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030
703-993-2326 FAX: 703-993-2323
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