Disabling chronic conditions in childhood
and social disadvantage: exploring the
temporal pathway
Dr Clare Blackburn, Professor Nick Spencer and Dr Janet Read
BACCH Annual Scientific Meeting 2012
Chronic disabling conditions in childhood
• In the UK, between 5% - 7% of children defined as disabled and
have legal entitlements under Equalities legislation
• Children with chronic disabling conditions experience greater
material hardship, adversity and social exclusion than other children
• Substantial impacts on children themselves, their families and on
health, social care and education systems
• Reducing both the prevalence of childhood disabling conditions and
the impact on the lives of children and their families is important
• Need for robust evidence
Current knowledge
• Aetiology not fully understood
• Large number of studies but many lack robust methods and
measures
• Cross-sectional studies give a snapshot of the circumstances of
disabled children and their households at specific point in time
• Need longitudinal studies to answer questions about causality (World
Report on Disability 2011)
Our study
• Data from a systematic review and secondary analysis on ONS
Longitudinal study
• We use the term ‘children with chronic disabling conditions’
• ‘disability is an evolving concept…..disability results from the
interaction between persons with impairments and attitudinal
and environmental barriers that hinders their full and effective
participation in society on an equal basis with others’ (UNCRPD)
The study: acknowledgements
•
Thanks to the project advisory group for their support and guidance: Rachael Barnes,
Liz Willetts, Jan Sunman, Grahame Whitfield, Eric Emerson, Neil Raymond .
•
We would like to acknowledge the help we received with this major literature review from
Diane Clay who did the searches and Jas Bain who sourced the papers for review,
helped us organise the data and provided administrative support.
•
The permission of the Office for National Statistics to use the Longitudinal Study is
gratefully acknowledged, as is the help provided by staff of the Centre for Longitudinal
Study Information & User Support (CeLSIUS). CeLSIUS is supported by the ESRC
Census of Population Program). The authors alone are responsible for the
interpretation of the data.
•
Census output is Crown copyright and is reproduced with the permission of the
Controller of HMSO and the Queen's Printer for Scotland.
•
This work was supported by the Economic and Social Research Council [grant number
RES-062-23-2883].
What does the international literature tell us
about childhood disability and social
disadvantage in high income countries?
How we searched the literature
We conducted a systematic review of population-based studies which reported data
on the association of socio-economic status (SES) with chronic disabling
conditions in childhood in high income countries
We searched a wide range of electronic databases (including Medline, Embase,
Psych-Info, EBSCO, Web of Science) and other sources
Inclusion criteria:
1. Published between 1st January, 1991 to 8th February 2011
2. Original study [reviews excluded]
3. Relationship of SES with chronic disabling conditions in childhood reported
4. Reported conditions must be chronic AND associated with limitation of normal
daily activity
5. Whole population studies – studies of selected population groups excluded
6. Studies using valid SES measures
7. High income countries
How many papers/reports did we find?
Abstracts identified by search
4620
Full papers/reports obtained
699
Main exclusions:
Not chronic/limiting
SES/disability relation not
reported
Not whole population study
Included studies/reports
134
What do the included papers show?
• Studies from 15 countries – majority from UK and USA
• 83.6% show a statistically significant relationship with social
disadvantage (low income/poverty/low education [usually
maternal]/ low occupational social class/ area-based
deprivation) by at least one outcome – see following slides
• Not all conditions associated with social disadvantage – Type 1
Diabetes Mellitus & less common psychological disorders such
as autism show no relationship & Crohn’s disease appears to
have a positive relationship with social advantage
Chronic disabling conditions (CDCs) 1
CDCs
combined
Psych
disorder
(any)
ID (all;
mild;
mod/
severe)
CP
Epilepsy
Asthma
(severe/
hospital)
20
58
23
6
7
9
Related to 17
low SES
(p<0.05)
50
23
6
5
7
Related to None
high SES
(p<0.05)
1
None
None
None
None
Number
of studies
Chronic disabling conditions
(CDCs) 2
Neural
Tube
defects
Cleft lip
& palate
Hearing
Vision
Congenital
anomaly
Other
6
4
6
4
6
8
Related to 4
low SES
(p<0.05)
3
4
2
3
3
Related to None
high SES
(p<0.05)
None
None
None
None
1
Number
of studies
Focus on specific outcomes: Chronic
disabling conditions combined
• These studies were of particular relevance to our project as we
studied all chronic disabling conditions in the Office of National
Statistics Longitudinal Study (ONSLS)
• Countries: 9 UK; 7 USA; 2 Nordic; 1 Canada; 1 Canada & UK
• Study design: 19 Cross-sectional; 1 longitudinal
• Range of ages but mainly covering ages from 2 to 17 years
• Overall clear evidence of relationship with social disadvantage
Meta-analysis of CDCs combined
Summary meta-analysis plot [random effects]
Blackburn
1.49 (1.30, 1.71)
Hogan
1.40 (1.28, 1.52)
Lipman 6-11
1.58 (1.04, 2.38)
Lipman 12 -16
1.53 (1.04, 2.23)
Newacheck 1
1.80 (1.64, 1.99)
Newacheck 2
2.71 (2.04, 3.71)
Nikiema Quebec
8.01 (2.83, 22.70)
Nikiema UK
1.69 (1.26, 2.25)
Reinhardt
1.19 (0.95, 1.48)
Spencer
3.40 (3.12, 3.70)
Currie
1.71 (1.57, 1.86)
N/check3
1.87 (1.64, 2.14)
Berntsson '84
1.09 (0.93, 1.27)
Berntsson '96
1.24 (1.08, 1.42)
combined
1.73 (1.41, 2.12)
0.5
1
2
5
10
odds ratio (95% confidence interval)
100
Focus on specific outcomes:
2. Intellectual disability (ID)
• These studies include those reporting on mild ID (IQ 50-70),
moderate/severe (<50) and on all ID (<70)
• Countries: 8 UK; 8 USA; 4 Finland; 2 Australia; 1 Israel
• Study design: 9 cross-sectional; 6 routinely collected data; 4
longitudinal; 4 case-control
• Range of ages: child (<13) = 7; adolescent (13+) = 1; child &
adolescent = 15
• Both mild and moderate/severe ID related to social
disadvantage (see next slide)
Meta-analysis of moderate/severe
ID
Summary meta-analysis plot [random effects]
Chapman
2.50 (2.10, 2.90)
Croen
2.50 (1.70, 3.30)
Leonard
2.58 (1.20, 5.58)
M/koski
2.70 (0.20, 30.40)
Drews
1.70 (0.90, 3.20)
Heikura'66
2.00 (0.80, 4.90)
Heikura'86
3.10 (1.40, 6.70)
Resnick
1.75 (1.47, 2.09)
combined
2.19 (1.84, 2.62)
0.2
0.5
1
2
5
10
odds ratio (95% confidence interval)
100
Focus on specific outcomes:
3. Cerebral Palsy (CP)
• These studies include those reporting on children born with CP
and CP acquired usually due to trauma
• Countries: 3 UK; 1 USA; 1 Sweden; 1 Denmark
• Study design: 3 routinely collected data; 2 register-based; 1
longitudinal
• Range of ages: most diagnosed by age 2 years
• Relationship to SES disputed in past but our findings suggest
social disadvantage is associated with CP
Meta-analysis of Cerebral Palsy
Summary meta-analysis plot [random effects]
Dolk
1.60 (1.24, 2.07)
Dolk
1.16 (1.00, 1.35)
Hjern
1.45 (1.15, 1.83)
Hvidtjorn
1.66 (1.44, 1.91)
Sundrum
1.55 (1.06, 2.25)
combined
1.46 (1.23, 1.72)
1
2
odds ratio (95% confidence interval)
5
Focus on specific outcomes:
4. Visual impairment
• These studies include children reported to be visually impaired
by their parents
• Countries: 1UK; 1 USA; 1 Nordic countries; 1 Australia
• Study design: 2 Cross-sectional; 2 Longitudinal
• Range of ages: 2 in early childhood (<9); 2 across childhood &
adolescence (0-17)
• Relationship with SES less clear than for other conditions partly
as very few studies & all parental report
Systematic review summary
• Our review indicates that chronic disabling conditions in childhood
are associated with social disadvantage in rich nations confirming
our UK findings
• Studies of the most common chronic disabling conditions in
childhood (psychological disorders, ID, CP and severe asthma)
are consistent in showing relationship with social disadvantage
• A few conditions show no relationship and only 2 studies suggest
a positive relationship with high SES
• More robust studies needed in relation to sensory impairment
Social disadvantage in early childhood
and the reported onset on chronic
disabling conditions in later
childhood/early adulthood
Exploring the temporal pathway
What did we want to find out?
Our research questions
In children without any reported chronic disabling conditions:
•Is exposure to social disadvantage in early childhood associated with
reported onset of chronic disabling conditions in later childhood?
•If so, is the association graded by degree of social disadvantage?
•In other words, is the risk of reported onset of a chronic disabling
condition in later childhood greater the poorer the child’s
circumstances?
Study design and methods
•
We analysed data from the Office for National Statistics Longitudinal Study
(ONS-LS)
•
The ONS- LS contains linked Population Census and vital event data for 1 per
cent of the population of England and Wales.
•
Information from the 1971, 1981, 1991 and 2001 Censuses has been linked
across censuses as well as information on events such as births, deaths and
cancer registrations.
•
ONS-LS also has data on other people living in the same household as ONSLS members e.g. parents
•
People with chronic disabling conditions identified through census question:
Do you have any long-term illness, health problem or disability that limits your
daily activities or the work you can do?
Children in the sample
• 61,603 children born between 1981 and 1991 who were ONS-LS
members and tracked in 1991 and 2001 Population Censuses
• Information on the children and their household circumstances
• Two groups:
– Index group: children reported as not having a chronic disabling
condition in 1991 but reported as having one in 2001 (2049 with
complete data)
– Comparison group: children not reported to have disabling chronic
condition in 1991 or 2001 (50790 with complete data)
Analysing the data
•
Used the data on household circumstances to construct a social
disadvantage index built up from 3 pieces of information (variables):
– Housing tenure: owner occupied v rented/other
– Social class of household: high (1-3 ) v low (4-5)
– Car/van ownership: 1 or more cars/vans v 0 cars/vans
•
Scored each factor (variable):
– 0 = no disadvantage
– 1 = indicates disadvantage.
– Scores summed to give an aggregate score of 0-3, where 0 = not
disadvantaged on any factor and 3 = disadvantage on all 3 factors
•
Logistic regression models
– Controlled for potential confounders: child’s age, child’s sex, child’s
ethnicity, family status
Data analysis
• Logistic regression models fitted on
index/comparison :
– Model 1: Social disadvantage index entered alone
– Model 2: Social disadvantage index plus child’s
age & sex
– Model 3: above plus child’s ethnicity
– Model 4: above plus family status
Findings
Children in the sample
Characteristics
p value
Index group
Comparison group
(no CDC in 1991 but developed CDC
by 2001)
n = 2049
(no CDC in 1991 or 2001)
n = 50790
Sex: Boys
Girls
55.2%
44.8%
50.8%
49.2%
<0.001
Mean age (‘01)
14.67
14.56
<0.01
Ethnicity:
White
Black
Indian
Pakistani/Bangladeshi
Other
91.7%
5.2%
0.5%
1.3%
0.8%
92.4%
5.2%
0.5%
1.5%
0.5%
Compared with White
group:
0.28
0.79
0.57
0.06
Family status in ‘91:
Lone parent household
16%
11.3%
<0.001
8.2%
12.6%
24.6%
54.6%
4.6%
8.1%
20.5%
66.8%
<0.001 (linear trend)
Social disadvantage index in ‘91:
Disadvantaged in 3 areas
Disadvantages in 2 areas
Disadvantaged in 1 area
Not disadvantaged
For children who didn’t have chronic
disabling conditions in 1991
• The reported onset of chronic disabling conditions in later childhood
was positively associated with exposure to social disadvantage in
earlier childhood
• This association persisted after controlling for the effect of child’s
age, sex, ethnicity and family status (see next slide)
• The odds of reported onset of chronic disabling conditions in later
childhood increased as the level of household disadvantage rose
• For children in the most disadvantage group in 1991, the odds of
reported onset of chronic disabling conditions by 2001 were more
than twice those for children living in the least disadvantaged
households.
Odds of a child without any reported chronic
disabling condition in 1991 reported as developing
one by 2001
Independent
variables
Model 1
Model 2
Model 3
Model 4
Odds ratio (95%CI)
Adjusted odds
ratio (95% CI)
Adjusted odds
ratio (95%CI)
Adjusted odds
ratio (95%CI)
Social disadvantage index
Disadvantage in 3
2.20 (1.86,2.59)*
2.21 (1.87,2.62)*
2.20 (1.87,2.62)*
2.11 (1.76,2.53)*
Disadvantage in 2
1.49 (1.25,1.79)*
1.50 (1.26,1.80)*
1.51 (1.26,1.81)*
1.45 (1.20,1.75)*
Disadvantage in 1
1.15 (0.94,1.41)
1.15 (0.94,1.41)
1.16 (0.95,1.41)
1.14 (0.93,1.39)
No disadvantage (ref)
1.00
1.00
1.00
1.00
Model 1: social disadvantage index
Model 2: social disadvantage, sex and age
Model 3: social disadvantage index, sex, age and ethnicity
Model 4: social disadvantage index, sex, age, ethnicity and family status
* P = or < 0.05
Population attributable risk
• For children reported as exposed to social
disadvantage in earlier childhood, the population
attributable risk for reported onset of chronic
disabling conditions in later childhood was 17.5%
• If all children had the same chances as children
reported as not exposed to social disadvantage in
earlier childhood, there would have been 359 fewer
children reported as having chronic disabling
conditions in later childhood.
Strengths and limitations of the study
•
•
Strengths:
• ONS-LS is a large, representative data source with sufficient power to
account for potential confounding by age, sex, gender, family structure,
social disadvantage
• Longitudinal design thus able to examine temporal ordering
(sequencing)
• High response rate (94%) due to legal requirement to complete census
form
Limitations
– Non-participation, loss at follow up, missing data are possible threats to
validity
– Participation in UK census is socially patterned, with lower response
from socially disadvantaged areas – findings likely underestimate the
impact of social disadvantage on the relationships considered
– 1991 and 2001 censuses used a single, generic question to identify
report chronic disabling conditions
In summary
Children reported as not having any chronic disabling conditions
when they were 0-10 years:
• Were at greater risk of being reported as having a chronic
disabling condition in later children (10-20 years) if they
experienced social deprivation in early childhood
• Their degree of risk was associated with the extent of social
disadvantage experienced
• The level of exposure to social disadvantage matters
Concluding remarks
•
Need for further studies to clarify length of exposure, clarify mechanisms and
pathways
•
Research is crucial to the development of policies and programmes to reduce
both the prevalence of childhood chronic disabling conditions and the impact
on the lives children and their families.
•
Issues of prevention of impairment and chronic disabling conditions need
careful and informed discussion
•
Need for a multi-dimensional strategy to reduce social disadvantage in early
childhood
•
In an age of austerity, children and their families are particular vulnerable