Transcript LSHTM February 23 2006 - IRR

The Global Burden of Disease
Due to Urban Air Pollution:
Estimates and Uncertainties
Aaron Cohen
Health Effects Institute
CRA project and WHR 2002
www.who.int/whr
www.thelancet.com
Urban Air Pollution Working
Group
H Ross Anderson (Co-Chair)
Aaron Cohen (Co-Chair)
Kersten Gutschmidt
Michal Krzyzanowski
Nino Künzli
Bart Ostro
Kiran Dev Pandey
Arden Pope
Isabelle Romieu
Jonathan Samet
Kirk Smith
SGHMS U London
Health Effects Institute
WHO/Geneva
WHO/Euro-Bonn
University of Basel
California Health Dept
World Bank
Brigham Young
PAHO
Johns Hopkins
UC Berkeley
The Global Burden of Disease Due
to Urban Air Pollution: Estimates
and Uncertainties
• The Global Burden of Disease
Comparative Risk Assessment
• Estimating the Global Burden of
Disease Due to Urban Air Pollution
• Magnitude and distribution of the
attributable burden
• Major sources of uncertainty
• Estimating the avoidable burden
Risk factors in CRA
Child & maternal under-nutrition
Childhood and maternal underweight
Iron deficiency
Vitamin A deficiency
Zinc deficiency
Other nutrition-related risks & inactivity
High blood pressure
High cholesterol
Overweight and obesity
Inadequate fruit and vegetable intake
Physical inactivity
Addictive substances
Smoking and oral tobacco
Alcohol
Illicit drugs
Environmental risks
Unsafe water, sanitation, and hygiene
Urban air pollution
Indoor smoke from solid fuels
Lead exposure
Climate change
Occupational risks
Risk factors for injury
Carcinogens
Airborne particulates
Ergonomic stressors
Noise
Other selected risks to health
Contaminated health care injections
Child sexual abuse
Sexual and reproductive health risks
Distributions of risks by poverty
Unsafe sex
Non-use and ineffective use of contraception
14 WHO mortality sub-regions
A: very low child and adult
mortality
B: low child and adult mortality
C: low child, high adult
D: high child, high adult
E: high child, very high adult
Basic CRA framework and goals
Risk factor levels
• current distribution
• counterfactual
distribution(s)
Risk factor-disease
relationships
• risk accumulation
• risk reversal
Disease burden
Attributable burden in 2000
Avoidable burden in 2010 & 2020
Mortality and Burden of Disease
• Mortality = Numbers of Deaths
• Burden = Disability Adjusted Life Year or
DALY
• DALY = YLL + YLD
• years of life lost because of premature death (YLLs)
• years of life lived with disability (YLDs)
• one DALY = one lost year of healthy life
Applying the CRA Methods to
Urban Air Pollution
• Choice of indicator pollutant and
estimation of ambient concentrations
• Choice of risk factor-disease
relationships
• Calculation of disease burden
Estimated PM10 Concentration in
World Cities (pop >=100,000)
PM10
(µg/m3)
.
5-14
.
15-29
.
30-59
.
60-99
. 100-254
Population Distribution of Estimated
PM10 Levels for 3200 Cities
Cohen et al 2004
American Cancer Society II Cohort
500, 000 adults followed 1982 – 1998
(Pope et al JAMA 2002)
RR per 10µg/m3 PM2.5 1979-83
RR
95% CI
Cardiopulmonary
1.06
1.02-1.10
Lung Cancer
1.08
1.01-1.16
Random effects Cox proportional hazards model controlling for age,
sex, race, smoking, education, marital status, body mass, alcohol,
occupational exposure and diet
Alternative Scenarios for Burden of
Disease Estimation for Urban Air Pollution
Alternative concentration-response curves for cardiopulmonary deaths
Base Case, PM2.5 Max=50
PM2.5 Max=30
Linear Extrapolation
Log-linear Extrapolation
RR
1.50
Counterfactual
level of 7.5 g/m3
1.25
1.00
0
5
10
15
20
25
30
35
40
45
50
55
PM2.5 (g/m3)
60
65
70
75
80
85
90
% change for 10 unit increase (ug/m3) in PM10
Percent change in mean daily number
of child and infant deaths
8.0
6.0
4.0
2.0
0.0
-2.0
-4.0
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Estimation of attributable deaths and
DALYs
1. Calculate region specific relative risk
RR2.5 = exp [CR * (X – 7.5)]
where CR is slope of the C-R function (β
coefficient) and X is regional population
weighted mean PM.
2. Calculate Attributable Fraction (AF)
AF = P(RR-1) / [ P(RR-1)+1]
where P is proportion exposed, i.e.
proportion living in cities
3. Calculate attributable deaths and
DALYs
(AF * regional totals)
Estimated Burden of Urban Air Pollution
Worldwide
(95% confidence intervals)
AF
(%)
CPD
Lung Ca
ARI (< 5yr.)
All-cause
(from timeseries studies)
Deaths
YLL
(thousands) (thousands)
4
712
4,666
(1, 6)
(245, 1107)
(1,695, 7700)
5
62
572
(1, 9)
(10, 114)
(92, 1,063)
1
26
862
(-1, 3)
(-24, 66)
(-799, 2,228)
1
(NA)
378
(NA)
(NA)
Fraction of Deaths Attributable to Outdoor
Urban Air Pollution by Region
Af
rE
Am
rA
Am
rB
Am
rD
Em
rB
Em
rD
Eu
rA
Eu
rB
Eu
rC
Se
ar
B
Se
ar
D
W
pr
A
W
pr
B
W
or
ld
Af
rD
10
9
8
7
6
% 5
4
3
2
1
0
LCA
CPD
ARI<5 yrs
Mortality attributable to leading risk factors
High blood pressure
Tobacco
High cholesterol
Underweight
Unsafe sex
Low fruit and vegetable intake
Overweight and obesity
Physical inactivity
Alcohol
Unsafe water, sanitation, and hygiene
High-mortality developing
Indoor smoke from solid fuels
Lower-mortality developing
Iron deficiency
Developed
Urban air pollution
Zinc deficiency
Vitamin A deficiency
Contaminated health care injections
Occupational airborne particulates
Occupational risk factors for injury
Lead exposure
Illicit drugs
0
Ezzati et al. 2002; WHO 2002
1000
2000
3000
4000
5000
6000
Mortality in thousands (Total 55.86 million)
7000
8000
Summary results for individual risks
• Substantial disease burden associated with risk factors such
as under-nutrition, poor water and sanitation, and indoor
air pollution remain, especially in the poorest developing
countries
• Simultaneously risks from a number of factors such as
smoking, alcohol, and obesity are becoming increasingly
global
• Some risks, like urban air pollution and lack of
contraception are major causes of burden in specific regions
Excess Deaths from Selected
Environmental Factors
Uncertainties that we quantified
• Random variation in exposure and risk
coefficient estimates
• Choice of PM2.5/PM10
• Choice of counterfactual level
• Choice of concentration-response
function: coefficients and extrapolation
Sensitivity of Attributable
Mortality Estimates
CP
LungCa
Trunc at 30
Full linear
Log-linear
Base 2.5/10
Min 3
Min 15
Av ACS coeff
-40
-20
0
20
40
% relative to base case
60
80
Uncertainties that we did not
quantify
• Burden due to pollutants other than PM, e.g.,
ozone
• Burden in cities with populations <100 K
• Effects of exposure at finer spatial scales e.g., due
to proximity to vehicular traffic
• Relative toxicity of PM from different sources
• Contribution of other potentially important health
outcomes, e.g., LBW, infectious disease
Leading Causes of Mortality and Burden of
Disease 2002
Mortality
•
•
•
•
•
•
•
•
•
•
•
%
Ischaemic heart disease
12.6
Cerebrovascular disease
9.7
Lower respiratory infections 6.8
HIV/AIDS
4.9
COPD
4.8
Perinatal conditions
4.3
Diarrhoeal diseases
3.2
Tuberculosis
2.7
Lung cancer
2.2
Malaria
2.2
Road traffic accidents
2.1
DALYs
•
•
•
•
•
•
•
•
•
•
•
Perinatal conditions
Lower respiratory infections
HIV/AIDS
Depression
Diarrhoeal diseases
Ischaemic heart disease
Cerebrovascular disease
Malaria
Road traffic accidents
Tuberculosis
COPD
%
6.5
6.1
5.7
4.5
4.2
3.9
3.3
3.1
2.6
2.3
1.9
Pediatrics 2005;115:121-128
Tuberculosis All Forms, WHO Regions, 2002
Western Pacific
24%
Africa
27%
Tuberculosis Deaths in HIV-Negatives, 2002
the Americas
4%
South-East Asia
33%
Eastern
Mediterranean
7%
Europe
5%
Western
Pacific
22%
Africa
19%
the Americas
3%
Eastern
Mediterranean
8%
8.9 Million Cases
South-East
Asia
43%
Europe
5%
1.6 Million Deaths
Air Pollution and TB
Millions of
Deaths
(% in
developing
countries)
% Global
Burden of
Disease
(% in
developing
countries)
1.6
(>90%)
2.5
(>90%)
4.8
(50%)
4.1
(>50%)
1.5-4.5
(ever/never)
Indoor Air
Pollution
1.6
(>95%)
2.6
(>95%)
1.8-3.6
(solid fuel use)
Urban Outdoor
Air Pollution
0.8
(>70%)
0.4
(>70%)
None reported
Tuberculosis
Smoking
Modified from Baris and Ezzati 2004
Range of
reported TB
relative risk
estimates
Attributable and avoidable burden
Exposure reduction
at T0
0%
Disease Burden
25%
c
50%
a
75%
d
Unavoidable
b
Past
T0
Time
Future
100%
(Theoretical
minimum)
Tx
What determines the health
effects of air pollution as
economies grow?
 Number of people in cities
 Sources of air pollution
 Emissions
 Air quality
 Susceptibility
Number of people at high CV risk 2000 - 2010
(A Rogers 2005)
36 m
46 m
38 m
18 m
50 m
16 m
5m
5m
12 m
45 m
7m
1m
19 m
4m
A: very low child and adult mortality
B: low child and adult mortality
C: low child, high adult
D: high child, high adult
E: high child, very high adult
>175 million people at
25%+ risk of a major CV
event in the next decade,
by WHO subregion
Reductions in Mortality in Dublin 72 Months
Pre- vs. Post-1990 Ban on Coal Sales
Adjusted % change
5
0
-5
-10
-15
-20
Clancy et al. Lancet 2002
Total non trauma
Cardiovascular
Respiratory
Other
Thank You
[email protected]