Hygeia and Panacea: is prevention better than cure?

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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

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ing p

rom

o

Wat

er p

ump

Latri

nes

Co

st/y

ear

hea

lth

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fe (

$/D

AL

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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