Research in Developmental Disabilities 35 (2014) 591–596
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Research in Developmental Disabilities
The self-rated health of British adults with intellectual disability Eric Emerson a,b, Janet Robertson a,*, Susannah Baines a, Chris Hatton a a b
Centre for Disability Research, Lancaster University, UK Centre for Disability Research and Policy, University of Sydney, Australia
A R T I C L E I N F O
A B S T R A C T
Article history: Received 21 November 2013 Accepted 3 January 2014 Available online 27 January 2014
People with intellectual disability have signiﬁcantly higher age-adjusted rates of mortality and morbidity than their non-disabled peers. While self-rated health status is commonly used as an indicator of the health status of populations of interest, few studies have explored the self-rated health of adults with intellectual disability. We undertook secondary analysis of de-identiﬁed cross-sectional data from the ﬁrst waves of two contemporary UK surveys: the Life Opportunities Survey (n = 37,513) and Understanding Society (n = 50,976). In the Life Opportunities Survey we identiﬁed 316 participants age 16– 49 (1.7% of the age-restricted sample) as having intellectual disability. In Understanding Society we identiﬁed 415 participants age 16–49 (1.5% of the age-restricted sample) as having intellectual disability. Participants with intellectual disability were signiﬁcantly more likely to report having fair or worse health than their peers (Life Opportunities Survey OR = 8.86 (6.54–12.01), p < 0.001; Understanding Society OR = 13.14 (10.65–16.21), p < 0.001). However the strength of this association was signiﬁcantly attenuated when risk estimates were adjusted to take account of the increased rates of exposure of participants with intellectual disability to socio-economic disadvantage and (in the Life Opportunities Survey) exposure to discrimination and violence. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Self-rated health Health Health disparities Socio-economic disadvantage Discrimination
1. Introduction People with intellectual disability have signiﬁcantly higher age-adjusted rates of mortality and morbidity than their nondisabled peers (Emerson & Hatton, 2014; Heslop et al., 2013; Krahn & Fox, in press). This evidence, when combined with expose´s of failings in healthcare systems (Heslop et al., 2013; Mencap, 2007, 2012; Michael, 2008) and increased attention to the human rights of disabled people (United Nations, 2006), has led regulatory bodies and governments to stress the importance of reducing the health inequalities experienced by people with intellectual disability (Department of Health, 2007; Disability Rights Commission, 2006; Krahn, Fox, Campbell, Ramon, & Jesien, 2010; Parliamentary and Health Service Ombudsman and Local Government Ombudsman, 2009; US Department of Health and Human Services, 2002). While self-rated health status is commonly used as an indicator of the health status of populations of interest (DeSalvo, Bloser, Reynolds, He, & Muntner, 2006; Idler & Benyamini, 1997, 1999; Jylha, 2009), few studies have explored the self-rated health of adults with intellectual disability (Emerson & Hatton, 2014; Fujiura, 2012). Of these, only three have employed relatively robust population-based sampling frames (Emerson & Hatton, 2008; Haider, Ansari, Vaughan, Matters, & Emerson,
* Corresponding author. E-mail addresses: [email protected]
(E. Emerson), [email protected]
(J. Robertson), [email protected]
(S. Baines), [email protected]
(C. Hatton). 0891-4222/$ – see front matter ß 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ridd.2014.01.005
E. Emerson et al. / Research in Developmental Disabilities 35 (2014) 591–596
2013; Larson, Lakin, Anderson, & Kwak, 2001) and only two of these collected information on the self-rated health of participants with and without intellectual disability (Haider et al., 2013; Larson, Lakin, Anderson, & Kwak, 2001). Larson and colleagues identiﬁed 3076 respondents with predominantly mild intellectual disability in the disability supplements to the 1994–95 US National Health Interview Survey (NHIS) (Larson, Lakin, & Anderson, 2003; Larson, Lakin, Anderson, & Kwak, 2001; Larson, Lakin, Anderson, Lee, et al., 2001). They reported that adults with intellectual disability were markedly more likely to rate their health as fair or poor (24%) than their peers without intellectual disability (10%). More recently, Haider and colleagues undertook a telephone survey of the health of 897 adults with intellectual disability in the State of Victoria, Australia (Haider et al., 2013). They reported that adults with intellectual disability were markedly more likely to rate their health (or have their health rated by a proxy) as fair or poor (24%) than their peers without intellectual disability (18%). Current knowledge indicates that the reasons for the poorer health of people with intellectual disability primarily fall within two broad spheres (Emerson & Hatton, 2014). First, a range of secondary health conditions is associated with some speciﬁc causes of intellectual disability (e.g., higher rates of congenital heart defects in children with Down syndrome). Second, people with intellectual disability are much more likely than their non-disabled peers to be exposed to a range of well-established social determinants of poorer health (e.g., poverty, social exclusion, discrimination, reduced access to timely and effective healthcare). To date no study has examined the extent to which the poorer self-rated health of adults with intellectual disability may reﬂect their increased rates of exposure to common social determinants of poorer health. However, previous research has demonstrated that: (1) poorer self-rated health among adults with intellectual disability is related to increased rates of exposure to indicators of socio-economic disadvantage and discrimination (Emerson, 2010; Emerson & Hatton, 2008); and (2) the poorer maternal-rated health of children with intellectual disability can be partially accounted for by their increased rates of exposure to indicators of socio-economic disadvantage (Emerson & Hatton, 2007a, 2007b). The aims of the present paper are: (1) to describe the self-rated general health status of British adults with intellectual disability; and (2) to examine the extent to which any between-group differences in health status may reﬂect betweengroup differences in rates of exposure to socio-economic disadvantage and discrimination.
2. Methods We undertook secondary analysis of de-identiﬁed cross-sectional data from the ﬁrst waves of two contemporary UK surveys; the Life Opportunities Survey (LOS)(Ofﬁce for National Statistics, 2011) and Understanding Society (McFall & Garrington, 2011). Data were downloaded from the UK Data Archive (http://www.data-archive.ac.uk/). Full details of the surveys’ development and methodology are available in a series of reports (Boreham, Boldysevaite, & Killpack, 2012; Buck & McFall, 2012; Dawe, 2011; Howe, 2010; McFall, 2012; McFall & Garrington, 2011; Ofﬁce for Disability Issues, 2011), key aspects of which are summarised below. 2.1. Samples LOS is a new longitudinal study focusing on the life experiences of disabled people in Great Britain (Dawe, 2011; Howe, 2010; Ofﬁce for Disability Issues, 2011). In the ﬁrst wave of data collection (undertaken between June 2009 and March 2011), random unclustered sampling from the small users Postcode Address File identiﬁed 34,004 eligible households. Interviews were completed with 37,513 individuals aged 16 or older from 19,951 households, giving a household response rate of 59% (Cuddeford, Duncan, Howe, & Glen, 2008; Dawe, 2011; Howe, 2010; Ofﬁce for Disability Issues, 2011). Understanding Society is a new longitudinal study focusing on the life experiences of UK citizens. In the ﬁrst wave of data collection (undertaken between January 2009 and December 2011), random sampling from the Postcode Address File in Great Britain and the Land and Property Services Agency list of domestic properties in Northern Ireland identiﬁed 55,684 eligible households. Interviews were completed with 50,976 individuals aged 16 or older from 30,117 households, giving a household response rate of 54% (Boreham et al., 2012; Buck & McFall, 2012; McFall, 2012; McFall & Garrington, 2011). 2.2. Procedures Data collection was primarily undertaken using Computer Assisted Personal Interviewing. 2.3. Measures 2.3.1. Intellectual disability Neither survey included information on the formal diagnosis of intellectual disability. As a result, we identiﬁed adults with intellectual disability on the basis of self-reported difﬁculties in learning or understanding coexisting with low selfreported educational attainment. Low self-reported educational attainment was used as a selection criterion for two reasons: (1) to exclude from the intellectual disability group respondents with speciﬁc learning disabilities such as dyslexia; and (2) as evidence that the person’s self-reported difﬁculty may have originated in childhood. Due to historical changes in educational qualiﬁcations and attainment in the UK, we further restricted our analysis to the age range 16–49.
E. Emerson et al. / Research in Developmental Disabilities 35 (2014) 591–596
Three inclusion criteria were used to identify LOS participants with intellectual disability: (1) a positive response to one of two impairment screening questions asked of all participants (Do you have a difﬁculty learning for example at school, college, work or in other places? Do you have an intellectual difﬁculty or developmental delay? This may not have a name but include things like Down’s syndrome, autism and other conditions); (2) they met the criteria for being considered disabled under existing UK legislation (deﬁned in the LOS data set by the extent of activity limitations/participation restrictions reported by respondents as a result of their impairment); and (3) their highest educational attainment was lower than a General Certiﬁcate of Secondary Education at Grade C or equivalent (24.3% of all LOS participants reported lower this level of attainment). This process identiﬁed 316 participants age 16–49 (1.7% of the unweighted age-restricted sample) as having intellectual disability. Men were signiﬁcantly more likely to be identiﬁed as having intellectual disability than women (2.1% vs. 1.3%, OR = 1.59 (95%CI 1.17–2.16), p < 0.01). Understanding Society uses a two-stage process for identifying participants with impairments or disability. First all participants are asked ‘Do you have any long-standing physical or mental impairment, illness or disability? By ‘longstanding’ I mean anything that has troubled you over a period of at least 12 months or that is likely to trouble you over a period of at least 12 months.’ If participants respond in the afﬁrmative they are then asked ‘Does this/Do these health problem(s) or disability(ies) mean that you have substantial difﬁculties with any of these areas of your life? Please read out the numbers from the card next to the ones which apply to you.’ One response option is ‘Memory or ability to concentrate, learn or understand’. We initially identiﬁed adults in US with potential intellectual disability on the basis of their positive response to this routed question. We then excluded from this group participants who did not meet the additional criteria of having a highest level of educational attainment lower than a General Certiﬁcate of Secondary Education or equivalent. Overall 22.5% of US participants reported lower than this level of attainment. This process identiﬁed 415 participants age 16– 49 (1.5% of the unweighted age-restricted sample) as having intellectual disability. Men were more likely to be identiﬁed as having intellectual disability than women (1.6% vs. 1.4%, OR = 1.10 (95%CI 0.90–1.33), n.s.). 2.3.2. Self-rated health Self-rated health was evaluated in both surveys by a single question incorporating ﬁve possible response options: LOS ‘How is your health in general; would you say it was. . . (1) very good, (2) good, (3) fair, (4) bad, (5) or very bad?’; Understanding Society: ‘In general, would you say your health is. . . (1) excellent, (2) very good, (3) good, (4) fair, (5) poor’. A binary measure of excellent/very good to good verses fair to very bad/poor self-rated health was derived for each participant (responses 1–2 vs. 3–5 in LOS, responses 1–3 vs. 4–5 in US). 2.3.3. Socio-economic disadvantage In both LOS and Understanding Society household socio-economic disadvantage was measured by a hardship scale. In LOS four items were included; ‘Looking at this card, can I just check whether your household could afford the following? (1) To pay for a week’s annual holiday away from home; (2) To eat meat, chicken or ﬁsh (or vegetarian equivalent) every second day; (3) Pay an unexpected, but necessary, expense of £500; (4) To keep your home adequately warm.’ A socioeconomic disadvantage score (0–4) based on the number of items that could not be afforded was derived for each participant. In Understanding Society eight items were included; ‘Next we have some questions about the sorts of things that some families/people have but which many people have difﬁculty ﬁnding the money for. For each of the following things please tell me the number from the showcard which best explains whether you (and your family/partner) have it or not. Do you (and your family partner) have. . . (1) A holiday away from home for at least one week a year, whilst not staying with relatives at their home? (2) Friends or family around for a drink or meal at least once a month? (3) Two pairs of all weather shoes for all adult members of the family? (4) Enough money to keep your house in a decent state of repair? (5) Household contents insurance? (6) Enough money to make regular savings of £10 a month or more for rainy days or retirement? (7) Enough money to replace any worn out furniture? (8) Enough money to replace or repair major electrical goods such as a refrigerator or a washing machine, when broken?’ The response options for each item were ‘1 I/We have this, 2 I/We would like to have this but cannot afford this at the moment, 3 I/We do not want/need this at the moment, 4 Does not apply’. A socio-economic disadvantage score (0–8) based on the number of items that could not be afforded was derived for each participant. 2.3.4. Discrimination and violence In LOS exposure to discrimination was measured by the following question; ‘In the last 12 months, do you feel that you have been treated unfairly by others for any of the reasons on this card? (1) age (2) sex (3) a health condition, illness or impairment, (4) disability related reasons, (5) ethnicity, (6) religion, (7) sexual orientation’. Exposure to violent crime in the last 12 months was measured by the following questions, with simple yes/no response options; ‘I would now like to ask you about crime. In the last 12 months, have you personally experienced any of the following. . . Violence or force used or threatened against you.’ Exposure to hate crime in the last 12 months was measured by the following two questions, each having simple yes/no response options. ‘A hate crime is one committed against you or your property on the grounds of your personal characteristics, for example religion, ethnic origin, disability or sexual orientation. Do you feel you have ever been a victim of a hate crime? Was this in the last 12 months?’ Information on discrimination and exposure to violence was not available in Understanding Society.
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Table 1 Self-rated health, socio-economic disadvantage and exposure over the preceding 12 months to discrimination, harassment and hate crime among participants aged 16–49 with and without intellectual disability. Study/variable Self-rated health Life Opportunities Survey Very good Good Fair Bad Very bad Fair-very bad Understanding Society Excellent Very good Good Fair Poor Fair-poor Socio-economic disadvantage Life Opportunities Survey Mean number of items cannot afford (range 0–4) Understanding Society Mean number of items cannot afford (range 0–8)
With intellectual disability
Without intellectual disability
19.5% 29.9% 32.2% 14.4% 4.0% 50.6%
53.4% 36.2% 7.7% 2.1% 0.5% 10.4%
Mann–Whitney U = 546,165, Z =
2.5% 8.0% 23.5% 34.0% 32.0% 66.0%
22.3% 36.7% 28.1% 9.8% 3.1% 12.9%
Mann–Whitney U = 1,476,432, Z =
Mann–Whitney U = 583,859, Z =
Mann–Whitney U = 2,328,729, Z =
Exposure over the preceding 12 months to discrimination and violence Life Opportunities Survey Treated unfairly 36.4% 12.3% Threatened or actual violence 13.2% 5.8% Victim of hate crime 8.3% 2.4%
13.15, p < 0.001
OR = 8.86 (6.54–12.01), p < 0.001 23.73, p < 0.001
OR = 13.14 (10.65–16.21), p < 0.001
12.09, p < 0.001 17.64, p < 0.001
OR = 4.06 (2.83–5.82), p < 0.001 OR = 2.47 (1.58–3.87), p < 0.001 OR = 3.71 (1.97–6.99), p < 0.001
3. Results Simple descriptive statistics on the self-rated health, socio-economic disadvantage and exposure over the preceding 12 months to discrimination, harassment and hate crime of participants with and without intellectual disability are presented in Table 1. As can be seen, in both data sets participants with intellectual disability had signiﬁcantly poorer self-rated health and were signiﬁcantly more likely to be exposed to socio-economic disadvantage than participants without intellectual disability. In LOS they were also signiﬁcantly more likely to have been exposed over the past 12 months to discrimination and violence. In order to examine the extent to which any between-group differences in health status may reﬂect between-group differences in rates of exposure to socio-economic disadvantage and discrimination we ﬁrst created binary variables in each data set denoting fair or poorer health. We then examined the strength of association between intellectual disability and fair or poorer health while sequentially adjusting for between-group differences in: (1) age and sex; (2) socio-economic disadvantage; and for LOS (3) exposure to discrimination and violence. The resulting analyses are presented in Table 2. As can be seen, in both data sets controlling for between-group differences in exposure to socio-economic disadvantage signiﬁcantly reduced but did not eliminate the association between intellectual disability and fair or poorer self-rated health. Estimating the magnitude of the reduction by 100*(model 1 idOR model 2 idOR)/(model 1 idOR 1) gives a 41% reduction in association in LOS and 34% reduction in US. Controlling for between-group differences in exposure to discrimination and violence in LOS led to a modest (21%) further reduction in the strength of the association between intellectual disability and fair or poorer self-rated health. 4. Discussion Our results indicate that: (1) British adults with intellectual disability have markedly poorer self-rated health than their non-disabled peers; and (2) that a signiﬁcant proportion of their risk of poorer self-rated health may be attributable to their poorer living conditions (rather than their intellectual disability per se). These results add to existing knowledge about the health inequalities faced by people with intellectual disability in ﬁve important ways. First, they add to the very sparse literature on the self-rated health of adults with intellectual disability (Emerson & Hatton, 2014; Fujiura, 2012). Second, they present the ﬁrst data on the extent to which risk of poorer self-rated health may be attenuated by taking into account between-group differences in living circumstances. Third, they add to the very sparse literature on the relationship between exposure to violence and discrimination and the health of adults with intellectual disability (Emerson, 2010). Fourth, they are based on the analysis of contemporary population-based sampling frames, a relative rarity in this ﬁeld of study (Emerson & Hatton, 2014). Finally, by being based on samples drawn from
E. Emerson et al. / Research in Developmental Disabilities 35 (2014) 591–596
Table 2 Strength of association (odds ratio with 95% conﬁdence intervals) between intellectual disability, socio-economic disadvantage, exposure to discrimination and violence and fair or poorer self-rated health. Life Opportunities Survey
Model 1 ***
Intellectual disability Socio-economic disadvantage Discrimination Violent crime Hate crime
Understanding Society Intellectual disability Socio-economic disadvantage
Model 1 12.28 (9.94–15.18)***
Model 2 (adjusted for socio-economic disadvantage) 6.59 (4.47–9.70)*** 1.76 (1.67–1.86)***
Model 3 (adjusted for socio-economic disadvantage, discrimination and victimisation) 5.41 (3.63–8.05)*** 1.68 (1.59–1.78)*** 3.05 (2.56–3.64)*** 1.78 (1.39–2.27)*** 1.11 (0.77–1.61)
Model 2 8.41 (6.75–10.49)*** 1.28 (1.26–1.30)***
Notes: All analyses adjusted for age and sex. *** p < 0.001.
general households participants are likely to include adults with less severe intellectual disability who may not be in receipt of specialised disability services. Given that most intellectual disability research is based on convenience samples drawn from the users of specialised disability services, very little is currently known about the health or well-being of this group that has been termed the ‘hidden majority’ of adults with intellectual disability (Emerson, 2011; Emerson & Brigham, 2013; Tymchuk, Lakin, & Luckasson, 2001). However, there are four limitations to the study that should be kept in mind when considering the salience and implications of these results. First, it is not possible to estimate the sensitivity or speciﬁcity of the method used to identify participants with intellectual disability in either survey. It should be noted, however, that: (1) the overall prevalence rates lies within the expected boundaries for intellectual disability (Maulik, Mascarenhas, Mathers, Dua, & Saxena, 2011) (2) the prevalence of intellectual disability varied with gender and indicators of socio-economic position in a manner consistent with previous epidemiological research (Maulik et al., 2011). Second, the use of general household sampling frames in both LOS and Understanding Society excludes people with (primarily more severe) intellectual disability living in more institutional forms of supported accommodation. Third, the consent and interview procedures used in LOS and Understanding Society are also likely to exclude people with more severe intellectual disability from participating. Consequently, the results are likely to be particularly relevant to understand the self-rated health of British adults with less severe intellectual disability. Finally, while the cross-sectional analyses presented in this paper are consistent with the hypothesis that the poorer self-rated health of adults with intellectual disability may be partially attributable to their poorer living conditions, it is not possible to rule out other explanations (e.g., people with intellectual disability are more susceptible to downward social mobility if they have poor health than their non-disabled peers). However, there is overwhelming evidence from the wider literature that the association between living conditions and health status is primarily driven by the causal inﬂuence of living conditions on health (Marmot, 2005; Marmot & Wilkinson, 2006; World Health Organization, 2008; World Health Organization Regional Ofﬁce for Europe, 2012). The primary implication of these results are that research, policy and practice in intellectual disability needs to take account of social context in understanding and ameliorating the health inequalities experienced by people with intellectual disability (Emerson, 2013; Emerson & Hatton, 2014; Emerson et al., in press). Key aspects of social context include exposure the range of environmental adversities associated with low socio-economic position (Emerson, 2013) and exposure to overt or personal and institutional discrimination (Emerson, 2010; Emerson & Roulstone, in press; Krieger, 1999). A secondary implication is that population health approaches to reducing health inequalities need to recognise people with intellectual disabilities (and people with disabilities more generally) as constituting a particularly ‘vulnerable’ group for poor health and ensure that generic programs and interventions are tailored to their speciﬁc needs and context (World Health Organization, 2011). 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