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Childhood disability and socio-economic circumstances in low and middle income countries: systematic review

  • Douglas E Simkiss1Email author,
  • Clare M Blackburn2,
  • Felix O Mukoro3,
  • Janet M Read4 and
  • Nicholas J Spencer5
BMC Pediatrics201111:119

DOI: 10.1186/1471-2431-11-119

Received: 4 August 2011

Accepted: 21 December 2011

Published: 21 December 2011

Abstract

Background

The majority of children with disability live in low and middle income (LAMI) countries. Although a number of important reviews of childhood disability in LAMI countries have been published, these have not, to our knowledge, addressed the association between childhood disability and the home socio-economic circumstances (SEC). The objective of this study is to establish the current state of knowledge on the SECs of children with disability and their households in LAMI countries through a systematic review and quality assessment of existing research.

Methods

Electronic databases (MEDLINE; EMBASE; PUBMED; Web of Knowledge; PsycInfo; ASSIA; Virtual Health Library; POPLINE; Google scholar) were searched using terms specific to childhood disability and SECs in LAMI countries. Publications from organisations including the World Bank, UNICEF, International Monetary Fund were searched for. Primary studies and reviews from 1990 onwards were included. Studies were assessed for inclusion, categorisation and quality by 2 researchers.

Results

24 primary studies and 13 reviews were identified. Evidence from the available literature on the association between childhood disability and SECs was inconsistent and inconclusive. Potential mechanisms by which poverty and low household SEC may be both a cause and consequence of disability are outlined in the reviews and the qualitative studies. The association of poor SECs with learning disability and behaviour problems was the most consistent finding and these studies had low/medium risk of bias. Where overall disability was the outcome of interest, findings were divergent and many studies had a high/medium risk of bias. Qualitative studies were methodologically weak.

Conclusions

This review indicates that, despite socially and biologically plausible mechanisms underlying the association of low household SEC with childhood disability in LAMI countries, the empirical evidence from quantitative studies is inconsistent and contradictory. There is evidence for a bidirectional association of low household SEC and disability and longitudinal data is needed to clarify the nature of this association.

Background

In 2004 the Global Burden of Disease report estimated that over 100 million children under the age of 15 years had a moderate or severe disability, the majority of whom live in low and middle income countries (LAMI) [1, 2]. Research on these children in LAMI countries however, has been described as 'woefully inadequate' [3]. Reviews of research have found that the majority of studies have focused on cross-sectional, community-based epidemiologic studies aimed at finding the prevalence or aetiology of certain conditions or impairments [3]. In addition, the quality of many studies has been judged inadequate [35]. It has been argued that it is important to move beyond prevalence studies to generate informative data on the circumstances of people with disability, including how these compare with those of their non-disabled peers [5]. There is now widespread acceptance that disability definitions and measures should no longer focus solely on impairments and other individual characteristics and conditions, important though those undoubtedly are. Definitions and measures of disability should also incorporate contextual dimensions which may enable or act as barriers to disabled children's participation and human rights [69]. A paradigm of disability, which incorporates both individual characteristics and social circumstances, is reflected in the recently developed International Classification of Functioning Disability and Health - Children and Youth (ICF-CY) [10] and the United Nations Convention on the Rights of Persons with Disabilities (UNCRPD) [11]. These factors make it an imperative to remedy the significant knowledge gap about the lives of children with disability in LAMI countries [1, 2, 12]. The World Disability Report [1] places emphasis on the role of environmental factors in disability; however, it identifies the absence of clarity on the relationship between household socio-economic circumstances and disability among both children and adults in developing countries. An important starting point is to scope existing studies that address this relationship.

Objective

A number of important reviews of childhood disability in LAMI countries have already been undertaken and point to significant gaps in knowledge about this important group of children and their families [3, 5, 1315]. The purpose of this paper is to establish the current state of knowledge on the socio-economic circumstances (SEC) of disabled children and their households in LAMI countries through a systematic review and quality assessment of existing research. We are taking a broad definition of disability consistent current thinking in the World Report on Disability and for the definition of SEC, we include the following variables; income/asset measures, parental education, poverty, area-based measures of socio-economic factors, occupation-based measures and housing-based measures. To our knowledge, this is the first review specifically reporting the association between childhood disability and the home socio-economic circumstances in LAMI countries.

Methods

We carried out a review of childhood disability in LAMI countries focusing on four areas: methodological issues in studying childhood disability; household SEC of children with disabilities; the rights of children with disabilities; the use of the International Classification of Functioning, Disability and Health - Children and Young people (ICF-CY) in relation in LAMI countries. This paper is concerned only with the household SEC of children with disability in LAMI countries. Further papers will address the literature related to the rights of children with disability and the use of the ICF-CY. The review by Maulik and Darmstadt [3] covers the methodological issues in detail and our review does not add significantly to their conclusions.

Search Strategy

Databases searched

The search for evidence explored six electronic databases, including medical literature (MEDLINE, EMBASE, and PUBMED), Web of Knowledge and CSA databases (PsycInfo, ASSIA). Broad searches were also conducted in Virtual Health Library, and POPLINE databases, as well as in Google scholar http://scholar.google.co.uk. Publications from organisations such as World Health Organisation (WHO), The World Bank and International Monetary Fund (IMF), United Nations Children's Fund (UNICEF); UN Statistics Division; Statistical Information and Monitoring Programme on Child Labour (SIMPOC); Development Banks (Inter-American; African; Asian); Save the Children; Washington Group; Paris21 consortium (Partnership in Statistics for Development in the 21st. century) and The Foundation for Scientific and Industrial Research (SINTEF) were screened. Bibliographies of selected articles were also searched. We set out to identify all relevant publications regardless of language. Only primary studies and reviews from LAMI countries evaluating SEC of disabled children, methodological issues in childhood disability data collection, the use of ICF-CY, and the rights of children with disability were considered eligible for review. Only literature published between 1990 and June 2009 were included because earlier papers may not now be relevant and the United Nations Convention on the Rights of the Child, the basis of children's rights, was published in 1989.

Search terms used

The search terms and strategies used for the searched databases are summarized in Table 1.
Table 1

Search terms by databases searched

Database

Search strategy

MEDLINE

exp Disabled Children/or exp Disabled Persons/

exp Sensation Disorders/or exp Learning Disorders/

exp Physical Impairment/

ICF-CY.mp. or international classification of function.mp.

exp Disability Evaluation/

child rights.mp. or exp Human Rights/

disability rights.mp.

1 or 2 or 3 or 4 or 5 or 6 or 7

exp Developing Countries/

8 AND 9

limit 10 to (yr="1990 - 2009" and ("infant (1 to 23 months)" or "preschool child (2 to 5 years)" or "child (6 to 12 years)" or "adolescent (13 to 18 years)"))

EMBASE

exp Handicapped Child/

exp Sensory Dysfunction/

exp Intellectual Impairment/or exp Hearing Impairment/

exp Disability/or exp Physical Disability/or exp Mental Deficiency/

exp Functional Assessment/or exp "International Classification of Functioning, Disability and Health"/or exp Classification/or ICF-CY.mp.

exp Human Rights/or child rights.mp.

disability rights.mp.

6 or 7 or 4 or 1 or 5 or 3 or 2

exp Developing Country/or low-income countries.mp.

9 and 8

limit 10 to (yr="1990 - 2009" and (infant < to one year > or preschool child <1 to 6 years > or school child <7 to 12 years > or adolescent < 13 to 17 years >))

PUBMED

("developing countries"[MeSH Major Topic]) AND ((("sensation disorders"[MeSH Major Topic]) OR ("mental retardation"[MeSH Major Topic])) OR ("disabled children"[MeSH Major Topic]))

Limits: Infant: 1-23 months, Preschool Child: 2-5 years, Child: 6-12 years, Adolescent: 13-18 years

VHL/POPLINE/Google Scholar

("disabled children" OR "disability" OR "ICF-CY") AND ("developing countries")

CSA (PsycInfo, ASSIA)

KW = ((disabled children) or ICF-CY or (disability rights)) or KW = ((sensation disorders) or (sensory impairment) or (mental retardation))

KW = ((developing countries) or (low - income countries) or (poor countries)) or KW = ((latin american countries) or (south east asian countries) or (south american countries)) or KW = ((african south of sahara) or (subsaharan african countries) or (low middle - income countries)) 1 AND 2

Inclusion criteria

Both primary studies and reviews relating to household SEC of children with disability in LAMI countries were included. Only quantitative studies with data on the association of childhood disabling conditions and household SEC were included. Seven studies that reported on children and adults combined with no separate analysis of childhood disability and household SEC were excluded. Qualitative studies and reviews were included if they reported on childhood and adult disability and household SEC.

Instrumentation

The studies were independently assessed for inclusion and categorization by two researchers, DS and NS. There was a very high level of 96% agreement overall and 92% for included studies, final decisions were made by agreement. All included studies were entered into a spreadsheet and then categorised using variables that included details of the research design, screening tools/method used, primary population studied, specific health condition and broad aim. The key focuses of the papers were categorized according to the broad themes including methodology, household socio-economic circumstances, rights, and ICF/ICF-CY. This paper is concerned only with those papers focusing on the household socioeconomic circumstances of children with disabilities.

Quality assessment

Papers were assessed for quality using the STROBE criteria http://www.strobe-statement.org modified for the specific requirements of the review (Table 2). Studies were judged to have low risk of bias if they had optimum quality in at least 6 out of the eight quality domains and no domains with least valuable quality. Studies with medium risk of bias were those with less than six optimum quality domains with only one least valuable quality domain or six optimum but with one least valuable domain. High risk of bias was defined as more than one least valuable domain or case series with no controls or comparison group.
Table 2

Quality assessment criteria

Quality criterion

Optimum

Adequate

Least valuable

Design & data collection methods

Longitudinal

Cross-sectional survey or case-control study

Case series without controls or comparison groups

Purpose

Specifically designed to collect childhood disability data

General purpose survey including questions on childhood disability

Inadequate childhood disability data

Data collection methods

Interview based

Interview based

Postal questionnaire based

Quantitative/qualitative

Combined quantitative & qualitative data on childhood disability

Quantitative only for prevalence estimation; qualitative only to study impact of disability on household

Either quantitative or qualitative data that cannot be adequately used to estimate prevalence or impact

Definitions & classifications of disability/impairment

Definition that is widely used, internationally validated & comparable with other data sets

Less than optimal definition but sufficiently detailed to allow reasonable prevalence estimates to be made

Unclear definition that does not allow comparison with other data sets

Sampling & sample

Representative of households with children in study country & sufficient size to enable prevalence estimates of less common impairments.

Representative of households with children in study country

Non-representative samples OR Small samples with inadequate numbers to make reliable prevalence estimates

Response rates

Full information on response rates with low non-response (< 10%)

Limited information on response rates or non-response (10-20%)

No response information or high response rates (> 20%)

Household measures of SES & socio-demographic characteristics

Data covering measures of income, parental education, household wealth & assets in addition to other socio-demographic characteristics including ethnicity, marital status, parental age, parental disability

Limited measures of SES such as maternal education only OR SES measures but limited data on other socio-demographic characteristics

No valid measures of SES or S-D characteristics

Information on child

Data on age, sex, school attendance

Limited information on age but no other data

No data on child - only on household as a whole

Information on children (< 19 years) living outside the home

Complete data on all children

Limited data on all children

No data on children living outside the home

Analysis

Summary findings related to the household SEC of disabled children in developing countries were extracted from primary studies and reviews identified by the search. The findings of qualitative studies were summarised. The association of household SEC with childhood disability was expressed as odds ratios with 95% confidence intervals where available or p values where odds ratios were not stated by the authors. Meta-analysis of the findings of the empirical studies was not attempted due to heterogeneity of the studies.

Results

24 primary studies of the relationship of childhood disability with family and household social circumstances in LAMI countries were identified [2, 4, 1638] (see Table 3). We found no reviews focusing specifically on the relationship of childhood disability with family and household social circumstances in LAMI countries. Three reviews [3941] set out to address the association of both adult and child disability with poverty in LAMI countries; a further 10 reviews [3, 5, 1315, 4246] refer to the association within the context of reviewing other aspects of disability in LAMI countries.
Table 3

Primary studies of household SEC of children with disabilities

Author/year/country

Study design

Population & sample

Disability measure

Measure of household SEC

Summary of results

[Odds ratios (OR) with 95% CIs where available]

Anselmi et al, 2008

Brazil 16

Prospective cohort study

601 children of 634 randomly selected from the Pelotas birth cohort & followed up between the ages of 4 & 12 years.

Emotional and behavioural problems measured using the Child Behavior Checklist (CBCL) administered at 4 & 12 years of age

Family income

Externalising (OR .72(.52,.96)) and internalising (OR .68(.47,.98)) behaviours and attention problems (OR .57(.39,.84)) at age 12 years were significantly associated with low family income at 4 years

Bashir et al, 2002 Pakistan 17

Prospective cohort study

772 children aged 4-6 years of age out of 1476 births enrolled in a birth cohort in 4 areas of Lahore with contrasting socio-economic characteristics

Mild Mental Retardation (MMR) measured as IQ in the range 50-69 measured using WISC & Griffiths tests among those initially identified using the Ten Question screening test

Four socio-economically distinct areas - village, periurban slum, urban slum & upper middle class area. [no individual or household level SES data reported]

MMR prevalence:

Upper middle class 1.4%

Village 4.8%

Urban slum 6.1%

Periurban slum 10.5%

Bastos et al, 1995

Tanzania 18

Cross-sectional survey

854 children aged 6 to 16 years in schools in the Moshi and Munduli districts of northern Tanzania

Hearing loss measured by pneumotoscopy and screening audiometry

Urban v. Rural areas

Hearing loss in speech frequency range more common in urban (37%) compared with rural (18%) and high frequency loss also more common in urban compared with rural

Durkin et al, 1998

Pakistan 19

Cross-sectional population survey

6,365 2-9 year old children in Greater Karachi screened in phase 1 of the survey using TQQ; 818 screening positive and 545 of those screening negative assessed in phase 2

Identification of mental retardation by: Phase 1: TQQ screen Phase 2: clinical assessment using Stanford-Binet IQ test & adaptive behaviour scale developed for Pakistani children

Maternal education level (Some v. None)

Urban v. Rural

Mild Retardation (IQ 50-70): No education OR 3.08(1.85,6.14) Rural OR 2.33(1.33,2.75)

Serious Retardation (IQ < 50): No education OR 3.25(1.86,8.43) Rural OR 2.21(0.87,5.57)

Filmer 2005

9 low & middle income countries (Jamaica, Romania, Cambodia, Indonesia, Mozambique, Burundi, Myanmar, Mongolia and Sierra Leone) 20

11 Nationally representative cross-sectional household surveys in 9 countries - 3 Living Standards Measurement Studies; 3 national socio-economic status surveys; 4 MICS 2 surveys; 1 DHS survey

Children & young people aged 6-17 years - population samples ranged from 1,649 in Jamaica (2000) to 64,136 in Indonesia (2000)

Impairment definitions of disability consistent with ICF's 'body functioning & structure' domain - range of different questions used

Quintiles of Household per capita consumption expenditure in LSMS & SES surveys

Quintiles of index of household consumer assets & housing characteristics in DHS & MICS2

Prevalence higher in poorest quintile compared with richest in all countries except Burundi, Cambodia, Mongolia and Mozambique - only Indonesia shows a clear social gradient across quintiles

Filmer 2008

13 low & middle income countries

(Jamaica, Romania, Cambodia, Indonesia, Mozambique, Burundi, Mongolia, South Africa, Chad, India, Colombia, Bolivia and Zambia) 4

[NB: some overlap with Filmer 2005] 20

14 Nationally representative cross-sectional household surveys in 13 countries - 2 Living Standards Measurement Studies; 5 national socio-economic status surveys; 2 MICS 2 surveys; 5 DHS surveys

Children & young people aged 6-17 years - population samples ranged from 5,865 in Burundi (2000) to 140,297 in India (1992)

Impairment definitions of disability consistent with ICF's 'body functioning & structure' domain - range of different questions used

Quintiles of Household per capita consumption expenditure in LSMS & SES surveys

Quintiles of index of household consumer assets & housing characteristics in DHS & MICS2

Only Indonesia & India show clear differences in disability prevalence between poorest & richest quintiles - otherwise non-significant differences

Grut & Ingstad, 2006

Yemen 21

Qualitative study

28 interviews involving 38 individuals in households with disabled people, & one group interview in an institution for disabled girls [15 children; 20 adults; 2 Disabled People's Organisations]

Range of disabilities including physical, intellectual, hearing & visual

[interviews of those with intellectual impairments conducted with parents in presence of the disabled person]

Specific measures not used but study does examine the impact of disability on the lives of households with disabled members particularly children and explores the association of poverty & disability

Complex relationship between disability and poverty demonstrated with insights into how disability and poverty interact to limit life chances

Hackett et al, 1999

India 22

Random cluster sampling for cross-sectional survey

1326 children aged 8-12 years in 2 local government districts outside the city of Calicut, Kerala State, India

Child psychiatric disorder identified in 2 phases:

Phase 1: Screening interviews using various instruments including Rutter's A2 scale plus Rutter teacher completed B2 scale

Phase 2: detailed psychiatric assessment of screen positive & 93 screen negative

Poverty index based on eight household characteristics

Father's occupation in 5 categories from professional to unskilled

Parental education level - age ceased formal education

Externalising behaviours: associated with low occupation group, low parental education & poverty

Internalising behaviours: associated with low parental education

Ingstad & Grut, 2007

Kenya 23

Qualitative study

42 interviews (27 individual; 4 group; 11 secondary information) including 16 children in 7 strategically chosen districts of Kenya

Range of disabilities including physical (33), intellectual/mental (9), hearing (8) & visual (5)

Specific measures not used but study does examine the impact of disability on the lives of households with disabled members particularly children and explores the association of poverty & disability

Complex relationship between disability and poverty demonstrated with insights into how disability and poverty interact to limit life chances

Kandamuthan, 1997

India 24

Case-control study nested within Health and Disability cross-sectional survey of 9652 households in 1983 in an area of Trivandrum, Kerala State.

180 children aged 0-14 years with identified disability compared with 900 controls.

Questionnaire & clinical assessment: 8 outcomes studied: total disabled; fits; speech & hearing disability; visual impairment; learning disability; strange behaviour; locomotor disability; other

20 SES measures used but not fully stated in the paper. Following univariate analysis, maternal education, family size and absence of latrine retained in multi-variate analysis

Total disability associated with: Low maternal education - adjusted OR 2.46 (1.03,5.89); Family size > 5 - adjusted OR 3.71(2.44,5.63); have latrine - adjusted OR 0.59(0.41,0.84)

Kuklina, 2006

Guatemala 25

Cross-sectional study nested within a birth cohort including all pregnancies between 1996 & 1999

385 children at 6 months of age; 342 at 24 months of age and 404 at 36 months of age in 4 villages in Eastern Guatemala

Neurodevelopment measured using the Mental Development and the Psychomotor Development indices of the Bailey Scales of Infant Development

Maternal education and household SES based on household characteristics and possessions

Maternal education & SES were not associated with child neurodevelopment

Loaiza & Cappa, 2005

7 low/middle income countries 26

Cross-sectional MICS2 surveys in Cameroon, Iraq, Jamaica, Lesotho, Madagascar, Sao Tome & Principe, and Suriname during the period 1999-2001

Children 2-9 years - sample sizes not stated

TQQ

Rural v. Urban

Maternal education

Wealth quintiles

Disability prevalence - tends to be higher in rural areas although varies by country; tends to be higher among less educated mothers but variable; variable relationship with wealth index - Suriname & Madagascar show social gradients in the expected direction but no significant differences in the other 5 countries

Meeks Gardner et al, 1995 & 1999

Jamaica 27, 28

[2 papers combined as same study described]

Nested randomised control trial within a larger study

78 stunted children & 26 non-stunted children in poor neighbourhoods of Kingston Jamaica - data collected at 12 & 24 months of age

Mental age measured using the Griffiths Global Development scores

Housing quality - measured by quality of sanitation & water supply and overcrowding

Caldwell HOME inventory - quality of home environment

Maternal score on Peabody Picture Vocabulary Test (PPVT) of verbal reasoning

Mental age at 12 & 24 months associated with maternal PPVT

Not associated with housing quality or HOME score

Mung'ala-Odera et al, 2006

Kenya 29

Cross-sectional survey

10218 out of 11416 children aged 6-9 years in the Kilifi district of Kenya (one of the poorest districts in the country - mainly subsistence farmers)

Neurological impairment measured in 2 phases: Phase 1 - TQQ screen

Phase 2 - psychological & neurological assessment undertaken by trained researchers among all screen +ve & similar number of screen -ve children

Maternal education

Mother not involved in economic activity

Father not involved in economic activity

Moderate/severe impairment NOT associated with any of the SES measures on univariate analysis

Natale et al, 1992

India 30

Cross-sectional survey

640 children aged 2-9 in households randomly sampled from 2 urban areas of Madurai, Tamil Nadu with contrasting socio-economic characteristics

TQQ screen with additional probe questions to ensure that only chronic conditions identified. TQQ responses grouped into 4 subscales - sensory; neuromotor; cognitive; verbal

Residence in one of 2 urban areas: one a slum area with residents of the lowest SES (monthly family income 10-15 US$/month); the other a slightly higher SES area (monthly family income 32-42 US$)

Overall disability: 17.4% in lowest SES area v. 8.2% in next lowest SES area

In logistic regression model adjusted for age, gender, birth order & number in family OR for lowest 2.39(1.82,3.09)

All subtypes except verbal significantly higher in lowest SES area

Rischewski, 2008

Rwanda 31

Nationwide matched case-control study (adults & children) nested within a national cross-sectional survey

93 cases aged < 15 yrs identified in the national survey matched for age & gender with 146 controls

Musculoskeletal impairment (MSI) ranging from knock knees to quadriplegia

Per capita household expenditure; x2 household asset possession measures

MSI in children < 15 NOT associated any of the household poverty measures

Shawky, 2002

Saudi Arabia 32

Case-control study based on four cross-sectional cohorts

1225 children aged 6-20 years with disabilities identified from specialist centres in Jeddah and 3405 non-disabled school children sampled from 42 boys' and 42 girls' schools

Auditory, visual & mental impairment

Maternal education; maternal working status

No maternal education associated with: auditory impairment OR 13.3 (7.2,27.8); visual impairment OR 3.7 (2.1,6.6); mental impairment OR 5.5 (3.8,8.1) - all adjusted for maternal age at birth, parity, working status, consanguinity & multiparity

Suris & Blum, 1993

> 20 countries - high & low income 33

Secondary data analysis of cross-sectional surveys

10-14 yr olds in 19 countries and 15-19 yr olds in 23 countries - only rates calculated - no numbers given. Data derived from UN International Disability Statistics Database (DISTAT)

No specific definition of disability stated - total disability rates as reported to UN

% female illiteracy

% country level female illiteracy not correlated with disability rates for adolescents in either age group

Izutsu et al, 2006

Bangladesh 34

Cross-sectional survey

Random samples of 187 boys & 137 girls from non-slum areas and 157 boys and 121 girls from slum areas of Dhaka aged 11-18 years

Mental health problems (Affective, anxiety, somatic, oppositional defiant & conduct problems plus ADHD) assessed using the Youth Self Report questionnaire administered in their homes by trained interviewers

Residence in slum or non-slum areas

Only conduct problems associated with living in slum areas OR 3.2(1.4,7.2) adjusted for gender, age & school enrolment

Thomas, 2005

Cambodia 35

Qualitative study

Key informant interviews at 3 centres for disabled persons in Cambodia - interviews with staff and administrators; focus group interviews - one with 13 disabled adults & one with 4 disabled children; home visits and interviews with four disabled adults and four disabled children & their parents

Range of different disabilities

Poverty

Poverty identified as both cause and consequence of disability - discussion of mechanisms by which poverty impacts on disability and vice versa based on qualitative data

Thomas, 2005

India 36

Qualitative study

Field visits to 7 centres for disabled persons. Focus group interviews with 27 at one centre & 12 at another centre. Small number of individual interviews with disabled persons or parents of disabled children

Range of different disabilities

Poverty

Poverty identified as both cause and consequence of disability - discussion of mechanisms by which poverty impacts on disability and vice versa based on qualitative data

Thomas, 2005

Rwanda 37

Qualitative study

Key informant interviews at 3 centres for disabled persons in Rwanda - 2 focus group interviews (27 and 20 disabled persons) and 4 individual interviews. No specific reference to interviews with children or parents of children.

Range of different disabilities

Poverty

Poverty identified as both cause and consequence of disability - not specific to children

UNICEF, 2008

18 low/middle income countries 2

MICS3 cross-sectional surveys in Albania, Bangladesh, Belize, Bosnia and Herzegovina, Cameroon, Central African Republic, Georgia, Ghana, Mauritania, Mongolia, Montenegro, Sao Tome & Principe, Serbia, Sierra Leone, Suriname, Thailand, TYFR Macedonia and Uzbekistan during the period 2005-2008

Children aged 2-9 years ranging from 1,537 children in Belize to 58,441 in Bangladesh

TQQ screening

Household wealth index (60% poorest v. 40% richest)

Maternal education

Rural/urban

Wealth index: only in 6 countries (Bangladesh, Georgia, Mongolia, Serbia, Sierra Leone & Thailand were disabled children at greater risk of living in the poorest 60% of households

Low maternal education: only 6 countries show a greater risk for disabled children of living in households with mothers with low education

Rural v. Urban: very little association of disability with rural living

VanLeit et al, 2007

Cambodia 38

Cross-sectional survey

500 children 0-18 years with disabilities - no controls included in the study

Full range of disabilities - objective was to identify the functional status of disabled children in Cambodia

Poverty (< 1$/day)

49% of households identified in the survey were living in poverty

Of the identified primary studies, 5 reported qualitative data within country level reports and 19 were quantitative studies conducted in more than 50 LAMI countries (Table 3). Five studies reported multi-country data, one of which [33] included developed countries as well as developing countries. The age range of children included in the quantitative studies varied from 0-20 years; eight studies reported on children under the age of 10 years, 2 on adolescents only and the remaining studies included young children as well as adolescents. The qualitative data included both adults and children; however, the ages of the children were not specified.

Two of the quantitative studies were based on prospective cohort studies [16, 17] and one (reported in two papers) on a randomised control trial [27, 28]; the remaining 16 were cross-sectional surveys or case-control studies (Table 3). A range of disabilities were studied in the quantitative studies; total disability rates were reported in 8 studies, emotional & behavioural disorders and mental retardation in 6, hearing loss in 2, visual impairment in 1, and neurological, neurodevelopment and musculoskeletal impairment in 4. The most commonly used instrument to measure disability in the quantitative surveys was the Ten Questions Questionnaire (TQQ); this was used in 8 studies, four as a screening tool in an initial phase of the study and four as the main measure of disability. The qualitative data were based on interviews and focus group including adults and children (or their parents) with a range of disabilities including hearing, visual, intellectual and motor impairment.

Eleven quantitative studies used multiple measures of household SEC. Parental education (mostly maternal education) and income/asset-based measures were the most commonly used measures. Six studies used area-based measures, two occupation-based measures and two housing-related measures. The poverty measures used in the reports containing qualitative data were not specified.

Although the reviews that primarily address disability and poverty [3941] categorically state that poverty is both a cause and consequence of disability, they review very limited empirical data on the relationship and none related specifically to the household SEC of children with disability in LAMI countries. As shown in Table 3 the qualitative data describe a close association of disability (both adult and child) with poverty; however, the association is not reported consistently in the quantitative studies. Potential mechanisms by which poverty and low household SEC may be both a cause and consequence of disability are outlined in the reviews and the qualitative studies. The reviews identified the living conditions of poor people in LAMI countries as a primary causal mechanism. Preventable impairments associated with communicable, maternal and perinatal disease and injuries [40], and malnutrition in childhood [39] were identified as key mechanisms by which poverty caused disability. The reviews (see particularly Mitra [41]) presented socially plausible mechanisms by which disability itself both in adults and children causes poverty and exacerbates existing poverty. Baylies [43] and Dudzik et al [44] identified social structures, war and social unrest which have the greatest impact on the poor as mechanisms linking poverty and disability. Smith [46] reviewing hearing impairment in developing countries, identified poor preventive health services as a factor in high prevalence of deafness and hearing impairment among children due to perinatal factors, chronic otitis media and ototoxic drugs.

The qualitative data provided further support for the role of poverty as both cause and consequence of disability. Ingstad and Grut [23], based on case studies derived from their fieldwork in Kenya, identified congenital conditions, conditions occurring in pregnancy and childbirth, malaria and epilepsy as mechanisms through which poverty leads to disability. All five reports contained rich data from their case studies illustrating how disability exacerbates and precipitates poverty.

Of the 8 studies reporting total childhood disability rates by household SEC, three were single country studies [24, 30, 38]. In Kandamuthan's case-control study [24] disabled children aged 0-14 years were more than twice as likely to have a mother with low education as their non-disabled peers. Natale et al's study [30] reported a more than twofold increase in prevalence of disability (17.4%) among children aged 2-9 years among those living in the lowest socioeconomic area compared with children living in a slightly more advantaged but still poor area (8.2%). Although VanLeit et al [38] report 49% of the children aged 0-18 years in their study living in poverty, their study has no control group so the significance of this finding is difficult to interpret. By contrast, there is no consistent association of total childhood disability with household SEC reported by the five multi-country studies [2, 4, 30, 26, 33]. Six out of the nine countries included in Filmer's study [20] show significant difference in prevalence of childhood disability by household SEC although only one, Indonesia, shows a clear social gradient. However, in the same author's 2008 study [4], in only two out of 13 countries, Indonesia and India, were significant differences between rich and poor households found. The studies by Loaiza & Cappa [26] and UNICEF [2], based on the Multi-Indicator Cluster Surveys 2 (MICS2) and 3 (MICS3) respectively, report variable findings with only a few countries showing significant relationships of total disability among 2-9 year old children with poorer household SEC. In their study, Suris and Blum [33] use United Nations disability data from both high and low/middle income countries to examine the association of country-level prevalence of disability among adolescents aged 15-19 years. They found no correlation of country level female illiteracy with prevalence of disability in this age group.

The six studies that examined the association of child mental illness, behavioural problems and mental retardation with household SEC [16, 17, 19, 22, 32, 34] all reported significant relationships with poor household SEC. Bashir et al [17], Durkin et al [19] and Shawky [32] reported a strong association of mild mental retardation with household SEC. Durkin et al [19] reported a strong association of severe mental retardation (IQ < 50) with no maternal education and rural living. Anselmi et al [16], in a prospective cohort study, found a significant association of externalising and internalising behaviours, and attention problems at age 12 years with low family income at 4 years of age. Hackett et al [22] reported similar findings in a cross-sectional survey. Izutsu et al [34] found a significant association of residence in a slum area with conduct problems but not with other behavioural difficulties.

None of the studies reporting on the association of neurological, neurodevelopmental and musculoskeletal problems with household SEC [25, 2729, 31] found any significant association. Shawky [32] in a case-control study, found a very high odds ratio (13.3(95% CI 7.2,27.8)) of children and young people aged 6-20 years with hearing loss having a mother with no education. Bastos et al [18] reported a two-fold increase in prevalence of hearing loss within the speech frequency range in urban areas (37%) compared with rural areas (18%) of northern Tanzania. The only study reporting on visual impairment [32] found a significant association with no maternal education.

The quality of included studies was variable. Table 4 summarises the quality assessment of the quantitative studies using the criteria listed in Table 2. Seventeen of the 19 quantitative studies had a medium or low risk of bias. The main sources of potential bias were single cross-sectional survey design and high or unreported non-response rates. Two studies had high risk of bias: Suris and Blum [33] as the study was based on national disability rates with no information on definitions, no information of how data were collected and only national level female illiteracy rates as a measure of socioeconomic status; VanLeit et al [38] as the study included only adolescents with disabilities with no comparison or control group.
Table 4

Quality assessment of quantitative studies

Study

Design

Purpose

Data collection methods

Sampling & sample size

Definitions

Response rate

Measures of home circumstance &/or SES

Child data

Overall risk of bias

Anselmi et al, 2008 16

Brazil

Optimum

Adequate

Optimum

Optimum

Optimum

Optimum

Adequate

Optimum

Low

Bashir et al, 2002

Pakistan 17

Optimum

Optimum

Optimum

Optimum

Optimum

Adequate

Adequate

Optimum

Low

Bastos et al, 1995

Tanzania 18

Adequate

Optimum

Optimum

Optimum

Optimum

Optimum

Least valuable (urban v. Rural)

Optimum

Medium

Durkin et al, 1998

Pakistan 19

Adequate

Optimum

Optimum

Optimum

Optimum

Optimum

Adequate

Optimum

Low

Filmer 2005

9 low & middle income countries 20

Adequate

Adequate

Optimum

Optimum

Optimum

Least valuable

Adequate

Optimum

Medium

Filmer 2008

13 low & middle income countries 4

[NB: some overlap with Filmer 2005] 20

Adequate

Adequate

Optimum

Optimum

Optimum

Least valuable

Adequate

Optimum

Medium

Hackett et al, 1999

India 22

Adequate

Optimum

Optimum

Optimum

Optimum

Adequate

Optimum

Optimum

Low

Kandamuthan, 1997

India 24

Adequate

Optimum

Optimum

Optimum

Optimum

Adequate

Optimum

Optimum

Low

Kuklina, 2006

Guatemala 25

Adequate

Optimum

Optimum

Adequate

Optimum

Adequate

Optimum

Optimum

Medium

Loaiza & Cappa, 2005

7 low/middle income countries 26

Adequate

Adequate

Optimum

Optimum

Optimum

Least valuable

Optimum

Optimum

Medium

Meeks Gardner et al, 1995 & 1999

Jamaica 27, 28

[2 papers combined as same study described]

Adequate

Adequate

Optimum

Adequate

Optimum

Optimum

Adequate

Optimum

Medium

Mung'ala-Odera et al, 2006

Kenya 29

Adequate

Optimum

Optimum

Optimum

Optimum

Adequate

Adequate

Optimum

Medium

Natale et al, 1992

India 30

Adequate

Optimum

Optimum

Adequate

Optimum

Optimum

Least valuable

Optimum

Medium

Rischewski, 2008

Rwanda 31

Adequate

Optimum

Optimum

Adequate

Adequate

Optimum

Adequate

Optimum

Low

Shawky, 2002

Saudi Arabia 32

Adequate

Optimum

Optimum

Optimum

Optimum

Optimum

Adequate

Optimum

Low

Suris & Blum, 1993

> 20 countries - high & low income 33

Least valuable

Optimum

Adequate

Least valuable - only national rates given

Least valuable - no information on definitions used

Least valuable

Least valuable - only national level of female illiteracy given

Least valuable

High

Izutsu al, 2006

Bangladesh 34

Adequate

Optimum

Optimum

Adequate

Optimum

Optimum

Least valuable

Optimum

Medium

UNICEF, 2008

18 low/middle income countries 2

Adequate

Adequate

Optimum

Optimum

Optimum

Least valuable

Adequate

Optimum

Medium

VanLeit et al, 2007

Cambodia 38

Least valuable

Optimum

Adequate

Adequate

Optimum

Optimum

Adequate

Optimum

High

The methodologies used in the country-based reports to collect qualitative data, while enabling rich data to be collected, had weaknesses related to inadequately described sampling methods and limited explanation of how themes and case studies were identified, selected and analysed. The samples included both adults and children limiting the validity of the findings for studying childhood disability.

Discussion

To our knowledge, this is the first review specifically reporting on the available literature on the association of childhood disability with home socio-economic circumstances in LAMI countries. We identified primary quantitative and qualitative studies and reviews that specifically addressed the household SEC of disabled children in LAMI countries. As this is a narrative review, we have not carried out meta-analysis of results of empirical quantitative studies.

Main findings

This review has shown that evidence from available literature on the association of childhood disability and household SEC in LAMI countries is inconsistent and inconclusive. This is likely to be due to differences in: measures of household SEC used in the studies; definitions of disability; outcomes studied; study design and methods. Some measures of household SEC, for example, residence in urban versus rural areas and female illiteracy rates are likely to be less precise than those based on individual household SEC measures. Studies using more than one measure of household SEC are more likely to identify associations with childhood disability than those using single measures as different measures may capture different pathways and mechanisms associated with the outcomes. For example, mild learning disability (termed mental retardation in the included studies) is likely to be associated with household education level while hearing impairment is likely to be associated with poor perinatal care and lack of preventive health care secondary to family poverty.

The definition of disability has developed in recent decades and the International Classification of Functioning, Disability and Health promotes a bio-psycho-social model that incorporates components of the medical and social models [10]. Disability arises out of the interaction between health conditions with contextual factors including the environment (SEC is part of this) and personal factors. With the United Nations Convention on the Rights of Persons with Disability, disability is becoming a rights based issue and its definition is changing [11]. However the literature described in this paper defines disability in terms of impairments.

The association of poor household SEC with learning disability and behaviour problems was the most consistent finding of the review. All six studies reported a positive association of poor household SEC with these outcomes and all these studies had a low or medium risk of bias. By contrast, studies with neurodevelopmental and neuromuscular problems as the outcome reported no association with poor household SEC. These studies also carried a low or medium risk of bias. One possible explanation for this differential association is that children with physical or neurological problems die prematurely and so are not available for counting whereas children with learning disability or behavioural problems survive; another explanation is that the neurodevelopmental and neuromuscular conditions may be more likely to have a genetic origin not associated with SEC.

Only two studies reported on hearing loss as the outcome of interest. They reported strikingly different associations with SEC. These divergent findings may be partly explained by the different measures of household SEC used.

The studies in which overall disability was the outcome of interest also reported divergent findings. The multi-country studies, based on secondary analysis of the UNICEF Multiple Indicator Cluster Surveys (MICS), Demographic and Health Surveys and other survey datasets, reported a positive association of childhood disability rates with poor household SEC in a few countries but no association in the majority of countries studied. Children with disability were identified using the TTQ in several of these studies. This instrument was designed with two stages; the questionnaire and then a clinical assessment of children who scored positively on the questionnaire. Unfortunately the clinical assessment is often not performed, making the TQQ invalid. One of these studies [33] had a high risk of bias; the other four studies had a medium risk of bias. A positive association of childhood disability rates with poor household SEC was reported by the three studies that collected and analysed primary data; however, one of these studies [38] had a high risk of bias as it was based on a case series with no control or comparison group.

The reviews identified by the search strategy reported socially and biologically plausible mechanisms by which poverty might be both a cause and consequence of disability. They identified the living conditions of poor people in LAMI countries as a primary causal mechanism; as Elwan [40] states "disability in developing countries stems largely from preventable impairments associated with communicable, maternal and perinatal disease and injuries". Malnutrition was identified as a specific cause of disability in childhood [39]. The reviews (see particularly Mitra [41]) presented socially plausible mechanisms by which disability causes poverty and exacerbates existing poverty.

The qualitative data from country-based reports had methodological weaknesses that limited the validity of their findings in relation to the association of poor household SEC with childhood disability. However, the studies provided further support for the role of poverty as both cause and consequence of disability. Ingstad and Grut [23], based on case studies derived from their fieldwork in Kenya, identified congenital conditions, conditions occurring in pregnancy and childbirth, malaria and epilepsy as mechanisms through which poverty leads to disability. All five studies reported rich data from their case studies illustrating how disability exacerbates and precipitates poverty.

Comparison with literature from high income countries and other literature from LAMI countries

To our knowledge, no equivalent review of the association of childhood disability with poor home circumstances/low SES in high income countries has been published. There is a substantial literature from the UK (for example, Gordon et al [47]; Blackburn et al 2010 [48], Emerson et al [49]), the USA (for example, Newacheck [50]; Newacheck and Halfon [51]) Australia (for example, Bor et al [52]; Leonard et al [53]) and Scandinavia (for example, Hjern et al [54]; Berntsson and Kohler [55]) showing that childhood disability is associated with higher risk of living in a poor/low income household. Gordon et al [47] assert that poverty in high income countries is both cause and consequence of childhood disability but we are not aware of specific studies confirming that poverty is causally related to disability in childhood.

The findings of this review are consistent with the literature in high income countries in that poverty is viewed as both cause and consequence of childhood disability; however, although there is strong evidence in both high income and LAMI countries for poverty as a consequence of disability, there are no empirical studies demonstrating the causal relationship of poverty to disability. Whereas studies from high income countries show a consistent association of childhood disability with poor home circumstances/low SES, the quantitative studies reviewed here show a much less consistent association. This is likely to result from differences in definition of disability, in data quality and sampling methods.

Three quantitative studies [5658] not included in this review as they did not analyse child and adult disability separately, reported lower incomes and fewer assets among households with disabled members (adults and/or children) and those with no disabled members in three sub-Saharan African countries (Namibia, Malawi and Zimbabwe). Their findings indicate that the use of rigorous research methodology with attention to sampling, disability definition, and detailed measurement of household SEC can result in very similar findings in different countries.

Limitations

Publication bias is a possible threat to the conclusions of this review. Although we aimed to identify a broad range of journal papers and reports on childhood disability, we did not include a search of grey literature, hand-searching of key journals or advice from key informants. As a consequence, the review is unlikely to include all available studies of the links between household SEC and childhood disability in LAMI countries. We used general search terms for disability, did not include specific diagnoses and chose to limit the search to publications from 1990 onwards in order to exclude studies with outdated information and to limit the volume of literature identified. This may have led to significant omissions from the review.

Implications for further study

The reviews and qualitative studies included in this review suggest that poverty is both a cause and consequence of disability in childhood. They outline biologically and socially plausible mechanisms by which poverty may exert its influence. By contrast, the empirical studies reviewed here report an inconsistent association of household SEC with childhood disability. Further research in this area is essential to clarify the relationship. The findings of this review, and those of Maulik and Darmstadt [3] indicate the need to address the following issues in future research into the association of childhood disability with household SEC:

Definitions of disability - although many of the studies reviewed here clearly stated the definitions used, there is a need, as Maulik and Darmstadt [3] point out, for consistency and standardisation of the definitions used and awareness of the problems of definition that impose limitations on conclusions that can be drawn

Types of disability - this review is consistent with Maulik and Darmstadt's [3] observation that the majority of studies focus on intellectual impairment and overall disability rates. Future studies could focus on other relatively common disabling conditions such as cerebral palsy. We found no studies using functional definitions of disability, such as defined in the ICF-CY - these would provide further valuable insights into the association with household SEC

Measures of household SEC - the review demonstrates that more than one measure of household SEC is necessary to study comprehensively the association with childhood disability as different measures such as maternal education and household wealth may have different associations with disability.

Study design - cross-sectional surveys, the most common design among the quantitative studies reviewed here, are relatively cheap to organise and are valuable for descriptive epidemiology. Further study to describe the relationship of childhood disability and household SEC will be valuable and cross-sectional surveys will continue to have a role. However, such surveys are only able to show associations; longitudinal prospective studies are necessary to comment on causal mechanisms particularly as relates to poverty as a cause rather than consequence of disability.

Mixed methods studies - the review shows that the qualitative studies provide valuable insights into possible social and biological mechanisms by which poverty might impact on disability. Future research would be strengthened by a mixed methods design that combined rigorous qualitative research preferably nested within a well-designed prospective quantitative study.

Conclusion

This review indicates that, despite socially and biologically plausible mechanisms underlying the association of low household SEC with childhood disability in LAMI countries, the empirical evidence from quantitative studies is inconsistent and contradictory. There is an urgent need for a more robust evidence base to inform the development of effective health and social policies aimed at reducing the burden of childhood disability in LAMI countries.

List of abbreviations

ICF-CY: 

International Classification of Functioning, Disability and Health - Children and Young People

IMF: 

International Monetary Fund

MICS: 

Multiple Indicator Cluster Survey

LAMI: 

Low and middle income

Paris21: 

Partnerships in Statistics for Development in the 21st century

POPLINE: 

Population information online

SEC: 

socio-economic circumstances

SIMPOC: 

Statistical Information and Monitoring Programme on Child Labour

SINTEF: 

The Foundation for Scientific and Industrial Research

TQQ: 

Ten Questions Questionnaire

UNCRPD: 

United Nations Convention on the Rights of Persons with Disabilities

UNICEF: 

United Nations Children's Fund

WHO: 

World Health Organization.

Declarations

Acknowledgements and funding

We thank the Institute of Advanced Studies (IAS) at the University of Warwick for funding that facilitated this research project. The IAS had no role in the study design; analysis and interpretation of data; in the writing of the manuscript; or in the decision to submit this manuscript for publication.

Authors’ Affiliations

(1)
Health Sciences Research Institute, Warwick Medical School, University of Warwick
(2)
School of Health and Social Studies, University of Warwick
(3)
NHS Kidney Care
(4)
School of Health and Social Studies, University of Warwick
(5)
School of Health and Social Studies, University of Warwick

References

  1. World Health Organization: World Report on Disability. 2011, Geneva: WHOGoogle Scholar
  2. Univeristy of Wisconsin and UNICEF: Monitoring Child Disability in Developing Countries: Results from the Multiple Indicator Cluster Surveys. 2008, New York: UNICEFGoogle Scholar
  3. Maulik PK, Darmstadt GL: Childhood disability in low-and middle-income countries: Overview of screening, prevention, services, legislation and epidemiology. Pediatrics. 2007, 120 (suppl): 1-55. 10.1542/peds.2007-0043B.View ArticleGoogle Scholar
  4. Filmer D: Disability, poverty, and schooling in developing countries: Results from 14 household surveys. The World Bank Economic Review. 2008, 141-163.Google Scholar
  5. Mont D: Measuring disability prevalence. Social protection discussion paper No 0706. 2007, Washington: The World BankGoogle Scholar
  6. Bickenbach J, Chatterji S, Badley E, Ustin T: Models of disablement, universalisim and the international classification of impairments, disabilities and handicaps. Social Science and Medicine. 1999, 48 (9): 1173-1187. 10.1016/S0277-9536(98)00441-9.View ArticlePubMedGoogle Scholar
  7. Wasserman D: Philosophical issues in the definition and social response to disability. Handbook of Disability Studies. Edited by: Seelman GK, Bury M. 2001, Thousand Oaks, California: Sage PublicationsGoogle Scholar
  8. Colver A, Dickinson H, SPARCLE group: Study Protocol: Determinants of participation and quality of life of adolescents with cerebral palsy: a longitudinal study (SPARCLE 2). BMC Public Health. 2010, 10: 208-10.1186/1471-2458-10-208.View ArticleGoogle Scholar
  9. McDougall J, Wright V, Rosenbaum R: The ICF model of functioning and disability: incorporating quality of life and human development. Developmental Neurorehabilitiation. 2010, 13 (3): 204-211. 10.3109/17518421003620525.View ArticleGoogle Scholar
  10. World health Organization: International Classification of Functioning, Disability and Health - Children and Youth Version. 2007, Geneva: WHOGoogle Scholar
  11. United Nations Conventions on the Rights of Persons with Disabilities. [http://www.un.org/disabilities]
  12. Gottlieb C, Maenner M, Cappa C, Durkin M: Child disability screening, nutrition, and early learning in 18 countries with low and middle incomes: data from the third round of UNICEF's Multiple Indicator Cluster Survey (2005-06). Lancet. 2009, 374 (9704): 1831-1839. 10.1016/S0140-6736(09)61871-7.View ArticlePubMedGoogle Scholar
  13. Davidson L, Durkin MS, Khan NZ: Studies of children in developing countries. How soon can we prevent neurodisability in childhood?. Developmental Medicine and Child Neurology. 2003, 45 (Suppl 96): 18-24.Google Scholar
  14. Msall ME, Hogan DP: Counting Children With Disability in Low-Income Countries: Enhancing Prevention, Promoting Child Development, and Investing in Economic Wellbeing. Pediatrics. 2007, 120: 182-185. 10.1542/peds.2007-1059.View ArticlePubMedGoogle Scholar
  15. Muñoz B, West S: Blindness and visual impairment in the Americas and the Caribbean. British Journal of Ophthalmology. 2002, 86: 498-504. 10.1136/bjo.86.5.498.View ArticlePubMedPubMed CentralGoogle Scholar
  16. Anselmi L, Barros FC, Teodoro ML, Piccinini CA, Menezes AMB, Araujo CL, Rohde LA: Continuity of behavioral and emotional problems from pre-school years to pre-adolescence in a developing country. Child Psychology and Psychiatry. 2008, 49 (5): 499-507. 10.1111/j.1469-7610.2007.01865.x.View ArticleGoogle Scholar
  17. Bashir A, Yaqoob M, Ferngren H, Gustavson K, Rydelius P, Ansari T, Zaman S: Prevalence and associated impairments of mild mental retardation in six- to ten-year old children in Pakistan: A prospective study. Acta Paediatrica. 2002, 91 (7): 833-837. 10.1111/j.1651-2227.2002.tb03336.x.View ArticlePubMedGoogle Scholar
  18. Bastos I, Mallyab J, Ingvarssona L, Reimerc Å, Andréasson L: Middle ear disease and hearing impairment in northern Tanzania: A prevalence study of school children in the Moshi and Monduli districts. International Journal of Pediatric Otorhinolaryngology. 1995, 32: 1-12. 10.1016/0165-5876(94)01904-C.View ArticlePubMedGoogle Scholar
  19. Durkin M, Hasan Z, Hasan K: Prevalence and correlates of mental retardation among children in Karachi, Pakistan. American Journal of Epidemiology. 1998, 147 (3): 281-288.View ArticlePubMedGoogle Scholar
  20. Filmer D: Disability, poverty and schooling in developing countries: Results from 11 household surveys. Social Protection. 2005, Washington DC: The World BankGoogle Scholar
  21. Grut L, Ingstad B: This is my life - Living with a disability in Yemen: A qualitative study. 2006, Oslo: SINTEF Health ResearchGoogle Scholar
  22. Hackett R, Hackett L, Bhakta P, Gowers S: The prevalence and associations of psychiatric disorder in children in Kerala, South India. Journal of Child Psychology and Psychiatry. 1999, 40 (5): 801-807. 10.1111/1469-7610.00495.View ArticlePubMedGoogle Scholar
  23. Ingstad B, Grut L: See me, and do not forget me: People with disabilities in Kenya. 2007, Oslo: SINTEF Health ResearchGoogle Scholar
  24. Kandamuthan M: Socio-economic factors and childhood disability in Trivandrum of South India. International Journal of Rehabilitation Research. 1997, 20: 335-339. 10.1097/00004356-199709000-00011.View ArticlePubMedGoogle Scholar
  25. Kuklina EV, Ramakrishnan U, Stein AD, Barnhart HH, Martorell R: Early childhood growth and development in rural Guatemala. Early Human Development. 2006, 82: 425-433. 10.1016/j.earlhumdev.2005.10.018.View ArticlePubMedGoogle Scholar
  26. Loaiza E, Cappa C: Measuring children's disability via household surveys: The MICS experience. Population Association of America. 2005, Philadelphia, PA, 27-Google Scholar
  27. Meeks Gardner JM, Grantham-McGregor SM, Himes J, Chang S: Activity and behavioral development in stunted and nonstunted children and response to nutritional supplementation. Child Development. 1995, 66: 1785-1797. 10.2307/1131910.View ArticlePubMedGoogle Scholar
  28. Meeks Gardner JM, Grantham-McGregor SM, Himes J, Chang S: Behaviour and development of stunted and nonstunted Jamaican children. Journal of Child Psychology and Psychiatry. 1999, 40 (5): 819-827. 10.1111/1469-7610.00497.View ArticleGoogle Scholar
  29. Mung'ala-Odera V, Meehan R, Njuguna P, Mturi N, Alcock K, Newton C: Prevalence and risk factors of neurological disability and impairment in children living in rural Kenya. International Journal of Epidemiology. 2006, 35: 683-688. 10.1093/ije/dyl023.View ArticlePubMedGoogle Scholar
  30. Natale JE, Joseph JG, Bergen R, Thulasiraj R, Rahmathulla L: Prevalence of childhood disability in a Southern Indian city: Independent effect of small differences in social status. International Journey of Epidemiology. 1992, 21 (2): 367-10.1093/ije/21.2.367.View ArticleGoogle Scholar
  31. Rischewski D, Kuper H, Atijosan O, Simms V, Jofret-Bonet M, Foster A, Lavy C: Poverty and musculoskeletal impairment in Rwanda. Transactions of the Royal Society of Tropical Medicine and Hygiene. 2008, 102: 608-617. 10.1016/j.trstmh.2008.02.023.View ArticlePubMedGoogle Scholar
  32. Shawky S, Abalkhail B, Soliman N: An epidemiological study of childhood disability in Jeddah, Saudi Arabia. Paediatric and Perinatal Epidemiology. 2002, 16: 61-66. 10.1046/j.1365-3016.2002.00365.x.View ArticlePubMedGoogle Scholar
  33. Suris J-C, Blum RW: Disability rates among adolescents: An international comparison. Journal of Adolescent Health. 1993, 14: 548-552. 10.1016/1054-139X(93)90139-G.View ArticlePubMedGoogle Scholar
  34. Izutsu T, Tsutsumi A, Islam AM, Kato S, Wakai S, Kurita H: Mental health, quality of life, and nutritional status of adolescents in Dhaka, Bangladesh: Comparison between an urban slum and a non-slum area. Social Science & Medicine. 2006, 63: 1477-1488. 10.1016/j.socscimed.2006.04.013.View ArticleGoogle Scholar
  35. Thomas P: Poverty reduction and development in Cambodia: Enabling disabled people to play a role. 2005, Disability Knowledge and ResearchGoogle Scholar
  36. Thomas P: Mainstreaming disability in development: India country report. Disability Knowledge and Research. 2005Google Scholar
  37. Thomas P: Mainstreaming disability in development: Country-level research- Rwanda country report. Disability Knowledge and Research. 2005Google Scholar
  38. VanLeit B, Channa S, Rithy P: Children with disabilities in rural Cambodia: An Examination of functional status and implications for service delivery. Asia Pacific Disability Rehabilitation Journal. 2007, 18 (2): 33-48.Google Scholar
  39. Department For International Development: Disability, Poverty and Development. 2000, London: DFID, 1-17.Google Scholar
  40. Elwan A: Poverty and disability: A survey of the literature. Social Protection Discussion Paper Series. 1999, Washington DC: The World BankGoogle Scholar
  41. Mitra S: Disability and social safety nets in developing countries. Social Protection Discussion Paper Series. 2005, Washington DC: The World Bank, 45-Google Scholar
  42. Andreassen R, Skøien R, Øderud T: Preliminary Study: Children with mobility limitations in Southern Africa. 2006, Norad, SINTEF and Norsk FormGoogle Scholar
  43. Baylies C: Disability and the notion of human development: Questions of rights and capabilities. Disability & Society. 2002, 17 (7): 725-739. 10.1080/0968759022000039037.View ArticleGoogle Scholar
  44. Dudzik P, Elwan A, Metts R: Disability policies, statistics, and strategies in Latin America and the Caribbean: A review. 2000, New York: Inter-American Development Bank (IDB)Google Scholar
  45. Miles S: Engaging with the Disability Rights Movement: The experience of community-based rehabilitation in southern Africa. Disability & Society. 1996, 11 (4): 501-517. 10.1080/09687599627561.View ArticleGoogle Scholar
  46. Smith AW: WHO activities for prevention of deafness and hearing impairment in children. Scandinavian Audiology. 2001, 30 (2): 93-100. 10.1080/010503901750166808.View ArticleGoogle Scholar
  47. Gordon D, Parker R, Loughran F, Heslop P: Disabled Children in Britain: A Re-Analysis of the OPCS Disability Surveys. 2000, London: The Stationery OfficeGoogle Scholar
  48. Blackburn CM, Spencer NJ, Read JM: Prevalence of childhood disability and the characteristics and circumstances of disabled children in the UK: seconary analysis of the Family Resources Survey. BMC Pediatrics. 2010, 10 (21):
  49. Emerson E, Shahtahmasebi S, Lancaster G, Berridge D: Poverty transitions among families supporting a child with intellectual disability. Journal of Intellectual and Developmental Disability. 2010, 35 (4): 224-234. 10.3109/13668250.2010.518562.View ArticlePubMedGoogle Scholar
  50. Newacheck PW, Yi Hung Y, Park MJ, Brindis CD, Irwin CE: Disparities in adolescent health and health care: does socioeconomic status matter?. Health Services Research. 2003, 38 (5): 1235-1252. 10.1111/1475-6773.00174.View ArticlePubMedPubMed CentralGoogle Scholar
  51. Newacheck PW, Halfon N: Prevalence and impact of disabling chronic conditions in childhood. American Journal of Public Health. 1998, 88 (4): 610-617. 10.2105/AJPH.88.4.610.View ArticlePubMedPubMed CentralGoogle Scholar
  52. Bor W, Najmen JM, Andersen J, Morrison J, Williams G: Socioeconomic disadvantage and child morbidity: an Australian longitudinal study. Social Science and Medicine. 1993, 36 (8): 1053-1061. 10.1016/0277-9536(93)90123-L.View ArticlePubMedGoogle Scholar
  53. Leonard H, Petterson B, De Klerk N, Zubrick SR, Glasson E, Sanders R, Bower C: Association of sociodemographic characteristics of children with intellectual disability in Western Australia. Social Science & Medicine. 2005, 60 (7): 1499-1513. 10.1016/j.socscimed.2004.08.014.View ArticleGoogle Scholar
  54. Hjern A, Weitoft G, Lindbald F: Social adversity predicts ADHD-medication in school children: a national cohort study. Acta Paediatrica. 2010, 99 (6): 920-924.View ArticlePubMedGoogle Scholar
  55. Berntsson LT, Kohler L: Long-term illness and psychosomatic complaints in children aged 2-17 years in the five Nordic countries. Comparison between 1984 and 1996. European Journal of Public Health. 2001, 11 (1): 35-42. 10.1093/eurpub/11.1.35.View ArticlePubMedGoogle Scholar
  56. Loeb M, Eide A: Living conditions among people with activity limitations in Malawi: A national representative study. 2004, Oslo: SINTEF Health ResearchGoogle Scholar
  57. Eide A, Nhiwathiwa S, Muderedzi J, Loeb M: Living conditions among people with activity limitations in Zimbabwe: A representative regional survey. 2003, Oslo: SINTEF UnimedGoogle Scholar
  58. Eide A, Van Rooy G, Loeb M: Living conditions among people with disabilities in Namibia. A national representative study. 2003, Oslo: SINTEF UnimedGoogle Scholar
  59. Pre-publication history

    1. The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2431/11/119/prepub

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.