Using GIS to investigate

multiple deprivation

David Briggs

Small Area Health Statistics Unit

Imperial College, London

A few thoughts and several questions

SAHSU and Environmental Injustice

• Socio-economic deprivation shows (often strong) associations with health outcome and exposure in most SAHSU studies

• Studies designed to minimise potential confounding by deprivation (small-area, case-crossover etc)

• Control is typically by using a (group-level) measure of socio-economic deprivation (Carstairs) in the logistic regression analysis

But….

• Do we over-control?

• Is deprivation really a confounder or effect-modifier?

• What is it about deprivation that affects health – and how should it be measured?

Question 1. Why are we interested in Environmental

Injustice

• Good science

• Good policy

• Moral justice

• Trendy subject

Landfill site density and population

density, UK Nr of landfill sites per 5 x 5 km21

2

3 - 4

5 - 8

9 - 68

0.00

1.00

2.00

3.00

4.00

5.00

6.00

0 - 9 10 - 19 20 - 29 30 - 39 40 - 49 50 - 59 60 - 69 70 - 79 80 - 89 90 - 100

Percentage Urban

Rat

e ra

tio

: ex

po

sed

/un

exp

ose

d

0

50

100

150

200

250

300

350

1 2 3 N/A

Nu

mb

er

of

po

stc

od

es

(th

ou

sa

nd

s)

< 2km

> 2km

Not known

Affluent Deprived

Proximity to landfill sites by

socioeconomic status and urban

area

0

20

40

60

80

100

0.00-0.10 >0.10-0.48 >0.48-1.00 >1.00-4.80 >4.79-10.0 >10.00

Distance from powerlines

Pe

rce

nta

ge

Affluent 2 3 4 Deprived

`

Socio-economic status by

distance from powerlines (km)

Odds ratios of living within 100 metres of a powerline, by

socio-economic status

0.6

0.8

1

1.2

1.4

1.6

1 2 3 4 5

Carstairs quintile

Od

ds

ra

tio

Affluent Deprived

1966-69

Black Smoke

Car

stai

rs

50 100 150 200 250

-50

510

15

1970-73

Black Smoke

Car

stai

rs

0 50 100 150 200

-50

510

15

1974-77

Black Smoke

Car

stai

rs

0 20 40 60 80 100 120

-50

510

15

1978-81

Black Smoke

Car

stai

rs

0 20 40 60 80

-50

510

15

1982-85

Black Smoke

Car

stai

rs

0 20 40 60

05

1015

1986-89

Black Smoke

Car

stai

rs

10 20 30 40 50 60

05

1015

1990-93

Black Smoke

Car

stai

rs

5 10 15 20 25 30 35

05

1015

Exposure to black smoke and deprivation for different time

periods, urban wards UK

Socio-economic deprivation and environment

Exposure Direction Comment

Traffic-related air pollution + Strong

Industrial air pollution + Strong

Road traffic noise + Strong

Aircraft noise +/ Varies by country

Disinfection byproducts +/ Varies by region

Landfill sites + Urban/industrial

Radon Rural/upland

Powerlines/EMF +/ Varies urban/rural

Mobile phone masts +/ Varies urban/rural

Question 2

How do these associations develop?

• Imposed (via planning process) – e.g. major point emitters?

• Evolved (as population changes in response) – e.g. roads, airports?

• Geographic coincidence (i.e. shared, but independent, geography of hazard and SES) – e.g. radon, powerlines?

• Historical legacy (i.e. inherited from past) – e.g. landfill sites

Health Period 1: 1981-84

Carstairs

Rela

tive R

isk

-5 0 5 10 15 20

1.0

1.5

2.0

Health Period 2: 1985-88

Carstairs

Rela

tive R

isk

-5 0 5 10 15 20

1.0

1.5

2.0

Health Period 3: 1989-92

Carstairs

Rela

tive R

isk

-5 0 5 10 15 20

1.0

1.5

2.0

Health Period 4: 1993-96

Carstairs

Rela

tive R

isk

-5 0 5 10 15 20

1.0

1.5

2.0 Respiratory deaths

Cardiovascular deathsAll deaths

Mortality and deprivation for four time periods:

urban wards, UK

Year Unadjusted

Adjusted

1981-84 1.11 1.06

1985-88 1.09 1.07

1989-92 1.05 1.06

1993-96 1.14 1.16

Adjusted and unadjusted risks of respiratory mortality for a 10

ppb increase in SO2

Outcome Mean 1% 99% Mean 1% 99%

Neural tube defects

1.07 1.02 1.12 1.05 1.01 1.10

Hypospadias/ epispadias

1.03 1.00 1.065 1.07 1.04 1.10

Abdominal wall defects

1.16 1.08 1.27 1.08 1.01 1.15

Stillbirths 1.04 1.02 1.05 1.00 0.99 1.02

Low birth weight

1.10 1.095 1.104 1.05 1.047 1.055

Very low birth weight

1.07 1.06 1.08 1.04 1.03 1.05

Abdominal wall defects*

1.13 1.03 1.24 1.07 0.98 1.18

Gastroschisis/ exomphalos*

1.26 1.12 1.42 1.19 1.05 1.34

Unadjusted Adjusted

Landfills: relative risks for ‘exposed’ versus ‘unexposed’

Outcome Mean 1% 99% Mean 1% 99%

Neural tube defects

0.98 0.82 1.16 1.05 0.99 1.10

Hypospadias/ epispadias

1.08 0.98 1.19 1.05 1.02 1.09

Abdominal wall defects

1.24 0.97 1.60 1.06 0.98 1.14

Stillbirths 1.01 0.96 1.06 1.02 1.00 1.03

Low birth weight

1.01 0.99 1.02 1.07 1.062 1.072

Very low birth weight

0.98 0.94 1.02 1.04 1.03 1.05

Abdominal wall defects*

2.26 1.23 4.15 1.12 1.01 1.25

Gastroschisis/ exomphalos*

1.33 0.46 3.81 1.24 1.09 1.42

Before operation During/after operation

* Hospital admissions

Landfills: relative risks for ‘exposed’ versus ‘unexposed’

Health outcome Direction Comment

Traffic accidents +Stronger for pedestrians

Lung cancer + Smoking related

Asthma — Weak

Cardio-vascular illness +

Pulmonary illness +

Congenital malformations

+ Limited evidence

All-cause mortality +

Non-lung cancers — Variable

Communicable diseases

+

Socio-economic deprivation and health

Affluent

Deprived

Exposure

Mort

alit

y

Socio-economic confounding

Deprived

Affluent

Deprived

Exposure

Mort

alit

y

Effect modification

Principle component 1 = traditional aspects of social deprivation; accounts for ca. 57% of the variation in the data and is closely associated with smoking

Principle component 2 = measures relating

to assets and income; accounts for ca. 15%

of the variation in the data

Question 3. How does environmental injustice

work?• What are the mechanisms by which socio-

economic status affects health?

• How do these combine/interact with environmental exposures to affect health?

• What aspects/components of SES?

• What aspects/components of environmental exposure

• Are they necessarily geographical?

• Is it the same everywhere (cultural determinants)?

• How do we study environmental injustice?

Well-being

Morbidity

Mortality

Exposure

Ambient environment

Community

Home

Health outcome

Preventive actions

Remedial actions

Actions

Contexts

Distal

Proximal

Less severe

More severe

Social conditions

Economic conditions

Demographic conditions

causes

attributable to

The ME-ME

Model

Physical injuries

Respiratory illness

Cognitive disfunction

Cardio-vascular disease

Ambient air

pollution

Noise pollution

Traffic accidents

Time activity

Indoor air pollution

Traffic density

Traffic speed

Indoor sources

Housing quality

Road conditions

Smoking

Exposure

Industrial emissions

Emission sources Proximity

Education

‘Road sense’

Diet

Socio-economic factors

Physical injuries

Respiratory illness

Cognitive disfunction

Cardio-vascular disease

Ambient air

pollution

Noise pollution

Traffic accidents

Time activity

Indoor air pollution

Traffic density

Traffic speed

Indoor sources

Housing quality

Road conditions

Smoking

Exposure

Industrial emissions

Emission sources Proximity

Education

‘Road sense’

Diet

Socio-economic factors

Diet

Questions 4+

What conceptual models do we have?

What IS environmental injustice?

What does it mean?

• For epidemiology

• For policy

• For the way we look at the world