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Hygeia and Panacea: is prevention better than cure?
CH
RIS
TO
PH
ER
DY
E
What's the single best method of prevention or
cure ever devised to improve public or personal health?
Prevention is better than cure Dangerous myth…
“Dad always thought
laughter was the best
medicine, which I guess is why several of us
died of tuberculosis.”
Prevention is better than cure …or universal truth?
Scurvy, "limeys" and vitamin C
James Lind 1716-94A Treatise of the Scurvy
Treatise on Preparation for DeathOn Civility in ChildrenAdagia
"Prevention is better than cure"
Desiderius Erasmus 1466-1536
1. When prevention is better than cure
Where 60 million people die double burden of disease in low-income countries
0
2
4
6
8
Communicable,pregnancy,
nutrition
Non-communicable
Injuries
Dea
ths
per
mill
ion
po
pu
lati
on
Low-middle income
High income
Currency of illness and death
WHAT'S THE HUMAN COST OF RABIES…
…AS COMPARED WITH HEART
DISEASE?
Currency of illness and death
HOW TO COMPARE RABIES WITH HEART DISEASE?
DISABILITY-ADJUSTED LIFE YEAR (DALY)
DALY = YEARS LOST TO ILLNESS
× DISABILITY WEIGHT
+ YEARS LOST BY DEATH
0
0.2
0.4
0.6
0.8
1
Upper
resp
Primar
y sy
philis
Asthm
a
Mea
sles
Liver
can
cer
TB
Lower re
sp
Heart
atta
ckAID
S
Men
inig
itis
Term
inal
can
cer
Death
pe
rfe
ct
he
alt
h...
...d
ea
thDisability weights for selected conditions
An ounce of prevention or a pound of cure?
100
1000
10000
100000
1000000
Tobaccoprice
increase
Nicotinereplacement
Promotingcessation
etc
Treatmentlung, liver,stomachcancer
Co
st/y
r h
ealt
hy
life
($/D
AL
Y)
TOBACCO: 5 MILLION DEATHS ANNUALLY
Tobacco tax works! Cigarette sales New Zealand
4
5
6
7
8
1980 1985 1990 1995 2000 2005
$ p
rice
20
cig
are
tte
s
6
8
10
12
14
Mill
ion
s s
old
DALYs: all we need to know?
Prevention or treatment of terminal cancer?
Choose:
(a) Palliative treatment to extend days of healthy life in people with cancer
Or:
(b) Preventive measures (advertising, taxation etc) to reduce cancer incidence
Assume cost per DALY is the same
"The benefits of strong, early action on climate change outweigh the costs"
STERN REVIEW November 2006: The Economics of Climate Change
Climate & health: An inconvenient truth?
Michael Mann's "hockey stick"
Global warming: damage to health
Rise ºC Some health consequences
1 300,000 people die each year from climate-related diseases - diarrhea, malaria, malnutrition
2 40 – 60 million more people exposed to malaria in Africa
3 1 – 3 million more people die from malnutrition (if carbon fertilization weak)
4 Up to 80 million more people exposed to malaria in Africa
5+ Major disruption and large-scale movement of population
Stabilization beyond reach?
Stabilization feasible
0
10
20
30
40
50
60
70
2000 2020 2040 2060 2080 2100
Glo
ba
l em
iss
ion
s (
GtC
O2
) Delayed action
Prompt action
Easier and harder ways to keep CO2
at or below 550 parts per million
"The cost of investment would be
trivial by comparison with the possible damage"
Investment 1% per year of global GDP over next 50 years
Damage2-3 ºC : 0-3% GDP in late 21st century5-6 ºC : 5-20% GDP ($4 trillion per year)
Bond…
“the rates of return from upfront investment in water and sanitation would significantly outweigh the costs of borrowing from bond markets…”
Human Development Report 2006
Market BondFinancing sanitation and vaccines
Smallpox: what value eradication?
Day 3
Synchronous eruption of lesions
Day 5
Rash turns to vesicles and pustules
Day 7
Large lesions with central well
Case fatality
30%
From inoculation to vaccination to eradication
Edward Jenner (1749-1823)
Lady Mary Wortley
Montague
(1689-1762)
DA HendersonWHO Eradication
campaign (1966-1977)
Smallpox inoculation: tools of the trade
Cost of eradication
inexternal funding
$125 million
"Just eradicate the disease, and
let the skeptics talk to each other" UNICEF
1967
About 10,000 cases per month
1977
Last case 26 October 1977
Poliomyelitis: prevention far better than cure
Polio vaccines
Sabin & Salk
Polio eradication?>1600 cases in 2006
Total external spending ~ $4 bnInitial estimate $300 million
IndiaPakistan
AfghanistanNigeria
2. When cure is the only option
Leprosy: curable but not preventable
3. When cure is also prevention
TUBERCULOSIS: 1.7 MILLION DEATHS ANNUALLY
1
10
100
1000
10000
100000
Treat latentinfection
Treatresistant TB
BCGvaccination
Treat activeTB
Co
st/y
r h
ealt
hy
life
gai
ned
($/
DA
LY
)
Cure
Prevention
4. When cure is the sister of prevention
Hygeia and Panacea cleanliness (and healing) are next to
godlinessAsklepios - medicine and healing
Hygeia - cleanliness
Panacea - healing
0
20
40
60
80
Bednets withinsecticide
Housespraying
insecticide
Prophylacticdrugs forchildren
Prophylacticdrugs in
pregnancy
Drugtreatment
children withmalaria
Co
st/
ye
ar
he
alt
hy
life
($
/DA
LY
)MALARIA:1.2 MILLION DEATHS ANNUALLY
Combine prevention and curelow- and middle-income countries: up to
4 methods of prevention 1 method of cure
0
1000
2000
3000
4000
5000
Wat
er &
sanit
ation
Choler
a or
rota
vacc
Oral r
ehyd
ratio
n
Breas
tfeed
ing p
rom
o
Wat
er p
ump
Latri
nes
Co
st/y
ear
hea
lth
y li
fe (
$/D
AL
Y)
Cure
Prevention
DIARRHEA: 1.8 MILLION DEATHS/YEARmethods for prevention and cure
The 60 countries with the highest numbers or rates worldwide of child mortality
-5 -4 -3 -2 -1 0
East Asia
Europe & Central Asia
Latin America
Middle East
South Asia
Sub-Saharan Africa
Annual fall in child mortality (U5M %)
Faster economicgrowthFall 1990-2000
target -4.3%
Child deaths: task is not to choose prevention or cure, but to implement all feasible solutions
Effective prevention and curePrevention Cure
Child deaths Breastfeeding handwashing
Oral rehydration
Antibiotics
Maternal deaths Family planning
Micronutrients
Obstetrics
Antibiotics
Nutrition Breastfeeding
Hygiene/sanitation
Macro- and micronutrients
HIV/AIDS Safe sex
Treat STI
Antibiotics
Antiretrovirals
Tuberculosis Treat active TB
BCG
Treat active TB
Treat TB/HIV
Malaria Bednets
House spraying
Case management
5. How individuals approach
prevention and cure
Why take the risk?
Are you "risk averse" or "risk prone"?
Plain ignorance (AIDS is not curable) It'll never happen to me (delusional) The future may never come
(discounting) Peer pressure (Kool and the Gang) For kicks (excitement, bore/freedom) Refusal to pay for insurance
Type of GambleExpected average valuerelative to amount bet
Roulette You lose 5% of each bet
Large group health insurance
You lose 10% of each bet
Individual health insurance
You lose 40% of each bet,the price of "peace ofmind"
Risk, roulette and health insurance
see www.gresham.ac.uk
6. Magic bullets & Nobel Prizes
Cure is cleverer than prevention?186 Nobel Prizes for Medicine, 1901-2006
Basic science 172Cure/therapy 12Prevention 2
Theiler 1905
Ehrlich 1908 +
Mechnikov 1908
Paul Ehrlich's (1854-1915)
"magic bullets"
Prevention: "side-chain" theory of immunity based on antibody
Cure: drugs selectively targeting pathogens -- arsenic-based Salvarsan to treat syphilis
Smoking one of his "25 strong cigars a day"Died of stroke
Magic bullets, besides penicillin…
Fleming Chain Florey
1928/41
Aspirin (acetylsalicylic acid, 1899)
Analgesic against minor pains and aches Antipyretic against fever Anti-inflammatory against arthritis Anti-platelet blood-thinner Anti-stick stops bacteria growing on
contact lenses Side effects gastrointestinal distress
(ulcers, stomach bleeding), tinnitus, bleeding in menstruation
Aspirin reduces strokes in women (17%) and heart attacks in men (32%)
women have slightly more strokes than heart attacks, men tend to have more heart attacks than strokes (JAMA vol 295, p 306, 2005)
Sir John Vane, Nobel Prize 1982
Praziquantel vs schistosome flukes
250 million people infected with schistosomes Adult flukes killed with a single dose of PZQ
Is prevention better than cure?
In formal analysis, not necessarily…
• Aetiology of some diseases unknown
some conditions unpreventable
• Prevention vs cure is not always the right question
both are needed and feasible e.g. child mortality in LDCs
• We value more than is captured in formal analysis
which gives guidance, not rules
PREVENTION VS CURE: A STRAW POLL AT WHO
0 1 2 3 4
Vaccination
Clean water
Handwashing
Nutrition
The pill
Seatbelts
Sterilization
Coveredcough
Vitamins
Votes for prevention
0 1 2 3 4 5
Antibiotics
Surgery
Gooddoctors
ORTdiarrhea
Votes for cure