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

Included studies/reports

134

Main exclusions:

Not chronic/limiting

SES/disability relation not

reported

Not whole population study

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

com-

bined

Psych

disorder

(any)

ID (all;

mild;

mod/

severe)

CP Epilepsy Asthma

(severe/

hospital)

Number

of studies

20 58 23 6 7 9

Related to

low SES

(p<0.05)

17 50 23 6 5 7

Related to

high SES

(p<0.05)

None 1 None None None None

Chronic disabling conditions

(CDCs) 2

Neural

Tube

defects

Cleft lip

& palate

Hearing Vision Con-

genital

anomaly

Other

Number

of studies

6 4 6 4 6 8

Related to

low SES

(p<0.05)

4 3 4 2 3 3

Related to

high SES

(p<0.05)

None None None None None 1

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-analys is plot [random effects]

0.5 1 2 5 10 100

combined 1.73 (1.41, 2.12)

Berntsson '96 1.24 (1.08, 1.42)

Berntsson '84 1.09 (0.93, 1.27)

N/check3 1.87 (1.64, 2.14)

Currie 1.71 (1.57, 1.86)

Spencer 3.40 (3.12, 3.70)

Reinhardt 1.19 (0.95, 1.48)

Nikiema UK 1.69 (1.26, 2.25)

Nikiema Quebec 8.01 (2.83, 22.70)

Newacheck 2 2.71 (2.04, 3.71)

Newacheck 1 1.80 (1.64, 1.99)

Lipman 12 -16 1.53 (1.04, 2.23)

Lipman 6-11 1.58 (1.04, 2.38)

Hogan 1.40 (1.28, 1.52)

Blackburn 1.49 (1.30, 1.71)

odds ratio (95% confidence interval)

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-analys is plot [random effects]

0.2 0.5 1 2 5 10 100

combined 2.19 (1.84, 2.62)

Resnick 1.75 (1.47, 2.09)

Heikura'86 3.10 (1.40, 6.70)

Heikura'66 2.00 (0.80, 4.90)

Drews 1.70 (0.90, 3.20)

M/koski 2.70 (0.20, 30.40)

Leonard 2.58 (1.20, 5.58)

Croen 2.50 (1.70, 3.30)

Chapman 2.50 (2.10, 2.90)

odds ratio (95% confidence interval)

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-analys is plot [random effects]

1 2 5

combined 1.46 (1.23, 1.72)

Sundrum 1.55 (1.06, 2.25)

Hvidtjorn 1.66 (1.44, 1.91)

Hjern 1.45 (1.15, 1.83)

Dolk 1.16 (1.00, 1.35)

Dolk 1.60 (1.24, 2.07)

odds ratio (95% confidence interval)

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 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 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 developing 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 ONS-

LS 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 Index group (no CDC in 1991 but developed CDC

by 2001) n = 2049

Comparison group (no CDC in 1991 or 2001)

n = 50790

p value

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

Social disadvantage index in ‘91: Disadvantaged in 3 areas Disadvantages in 2 areas Disadvantaged in 1 area Not disadvantaged

8.2%

12.6% 24.6% 54.6%

4.6% 8.1% 20.5% 66.8%

<0.001 (linear trend)

For children who didn’t have chronic

disabling conditions in 1991

• The 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 developing 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

developing 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 developing one by 2001

Independent variables

Model 1 Odds ratio (95%CI)

Model 2 Adjusted odds ratio (95% CI)

Model 3 Adjusted odds ratio (95%CI)

Model 4 Adjusted odds ratio (95%CI)

Social disadvantage index Disadvantage in 3 Disadvantage in 2 Disadvantage in 1 No disadvantage (ref)

2.20 (1.86,2.59)* 1.49 (1.25,1.79)* 1.15 (0.94,1.41) 1.00

2.21 (1.87,2.62)* 1.50 (1.26,1.80)* 1.15 (0.94,1.41) 1.00

2.20 (1.87,2.62)* 1.51 (1.26,1.81)* 1.16 (0.95,1.41) 1.00

2.11 (1.76,2.53)* 1.45 (1.20,1.75)* 1.14 (0.93,1.39) 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