Published for the British Institute of Learning Disabilities
Journal of Applied Research in Intellectual Disabilities 2015, 28, 383–393
Mortality among a Cohort of Persons with an Intellectual Disability in New South Wales, Australia Tony Florio*,† and Julian Trollor† *School of Psychological Sciences, Australian College of Applied Psychology (ACAP), Sydney, NSW, Australia; †Department of Developmental Disability Neuropsychiatry, UNSW, Sydney, NSW, Australia
Accepted for publication 22 April 2015
Objectives The main objective of the study was to compare mortality for people with an intellectual disability (ID) to the general population in New South Wales (NSW), Australia. A second objective was to provide mortality data for people with an intellectual disability from NSW in a standardized format, which allows for international comparisons of the mortality of people with an intellectual disability. Design and setting The study was a longitudinal cohort study linking retrospective data from the population databases of the NSW Department of Ageing, Disability and Home Care (ADHC) Intellectual Disability Services Dataset (intellectual disability cohort) to the mortality data set of the NSW Registry of Births, Deaths and Marriages (RBDM) for the period 1 June 2005 to 31 December 2011. Participants The two groups of interest for this study were persons with an intellectual disability recorded in the intellectual disability cohort (953 deaths among 42 219 persons over 270 649 person-years of observation) and the rest of the NSW population (312 649 deaths among over 7 218 529 persons [2011 population] and 45 818 946 person-years of observation). Main outcome measures In this study, we compared the intellectual disability cohort with the rest of the NSW population using age-adjusted death rates (ADRs), standardized mortality ratios (SMRs) and age standardized
Background The mortality of persons with an intellectual disability (ID) is higher than that of the general population (Patja et al. 2000; Bittles et al. 2002; Durvasula et al. 2002; Tyrer et al. 2007; Heslop et al. 2013). At a population level, © 2015 John Wiley & Sons Ltd
death rates (ASDRs) based upon the World Health Organization (WHO) standard population. Results We found a significantly higher mortality in a cohort of people with an intellectual disability compared to the rest of the NSW population. The intellectual disability cohort compared to the rest of the NSW population had an SMR of 2.48 for all ages and an SMR of 3.15 for those aged 5–69 years. We also found an SMR for females (4.26) with an intellectual disability that was significantly higher than that for males (2.52) with an intellectual disability. The ASDR for the intellectual disability cohort was 4.04 (deaths per 1000) and the ASDR for the rest of the NSW population was 1.58, giving a comparative mortality ratio of 2.55. Conclusions Our findings indicate excess mortality of people with an intellectual disability when compared to the general population. They also indicate that females with an intellectual disability have a higher relative mortality compared to female same-aged general population peers, and also males with an intellectual disability, a finding replicated in other similar cohort studies. For international comparison using the WHO standard population, our intellectual disability cohort (ages 5–69 years) had a mortality of 4.04 deaths per 1000. Keywords: Australia, cohort studies, disabilities, mortality, record linkage
intellectual
numerous factors operate to bring about this excess mortality: greater comorbidity of intellectual disability with other health conditions that have a high mortality (Forsgren et al. 1996; Bittles et al. 2007; Heslop et al. 2013), poorer access to appropriate health care (Beange et al. 1995), polypharmacy (Heslop et al. 2013), greater 10.1111/jar.12190
384 Journal of Applied Research in Intellectual Disabilities
engagement in lifestyles that promote and/or exacerbate illness (Beange & McKerras 1994), social and financial disadvantage (Emerson et al. 2007; Emerson 2012) and a lack of health self-care which is not corrected by formal and informal support (Beange et al. 1995). The relative excess mortality of people with an intellectual disability compared to their peers in any particular population is a function of the mixed operation of such factors over periods of time in that population. A first step in addressing the excess mortality for people with an intellectual disability, in a particular population, is to be able to quantify, measure and study the absolute and comparative mortality of people with an intellectual disability in ways that might provide new information that can be applied to mitigate specific factors which contribute to excess mortality in that population. Another strategy is to compare the rates of excess mortality of people with an intellectual disability between jurisdictions. International comparisons, in particular, have the potential to be highly informative. Systematic examination of rates of excess mortality of people with an intellectual disability, in different countries with known differences in some of the factors that can contribute to excess mortality, could provide valuable insights. Alternately, different countries with known rates of excess intellectual disability mortality can be compared for differences in factors which might account for the observed differences in excess intellectual disability mortality. The main objective of this study was to compare mortality for people with an intellectual disability to the general population in NSW, Australia, to measure the differential mortality of people with an intellectual disability. It is expected that people with an intellectual disability will have excess mortality compared to their population peers. A second objective was to provide mortality data for people with an intellectual disability from NSW in a standardized format, which allows for international and interstate comparisons of the mortality of people with an intellectual disability, between NSW, Australia, and elsewhere.
The Australian and New South Wales context Australia is an island continent country with a current population of over 23 million persons. Australia is a federation consisting of six states and two territories. The most populous state is New South Wales (NSW) with a current population of over 7.5 m. More than 85% of Australians live in urban areas and nearly 70% live in a state or territory capital city, making Australia one of the most urbanized countries in the world. The median
age in 2011 was 37 years, 14% of the population was aged over 65 years, life expectancy for a male at birth was 79.9 years and for a female 83.4 years, the crude death rate was 6.5 per 1000 of population, the sex ratio was balanced with 99 males for every 100 females, and the fertility rate was 1.9 babies per woman of child bearing age. Over one in four Australians (27%) were born outside of Australia, with migrants (the largest source of population growth for Australia) coming from many different parts of the world (most recently mainly from Asia), creating an ethnically diverse population. Indigenous Australians, also known as Aboriginal and Torres Strait Islanders, make up almost 3% of the population. All the above figures are from ABS (2014a). Australia has a substantial history of providing statefunded services to people with an intellectual disability. Prior to the mid-1980s, these services consisted almost entirely of large institutional residential services. A series of reforms since the 1980s has brought about a more diverse range of community-based services, which includes community-based group homes, developmental assessment services, early intervention services, respite group homes, community support teams, therapy (physiotherapists, occupational therapists and speech pathologists) and behavioural intervention services. The vestiges of large residential institutions still remain in a much diminished form, but are now a minor component compared to community-based services. At the current time, Australia is in transition from state-funded/ provided services to the provision of services under a National Disability Insurance Scheme. The hallmark of this scheme is individualized funding for the purchase of services in an insurance model in which federal and state governments pay an annual premium for the whole population. Individuals with a disability apply for and are funded to purchase services of their choice from a set of registered service providers. The announced timetable is that full transition will be completed by 2018, but it may prove to take longer. A consequence of the historical state funding of services to people with an intellectual disability is that administrative records have been kept by government departments for the purposes of managing these services. In the case of NSW, the largest state in Australia, the Ageing, Disability and Home Care (ADHC) branch of the NSW Department of Family & Community Services (FACS) has collected and electronically maintained records of persons who receive an intellectual disability service. As such, there exists an electronic register (dating back from the present to 2005) containing details of people of all ages, who are known to have an intellectual disability. © 2015 John Wiley & Sons Ltd, 28, 383–393
Journal of Applied Research in Intellectual Disabilities
To receive an intellectual disability service (and be placed on the register), a person undergoes an eligibility assessment conducted by a registered psychologist, which determines that the person meets the DSM-IV criteria for intellectual disability. Thus, the NSW ADHC administrative ID Service Register forms the basis for defining a cohort of persons with an intellectual disability. In NSW, the NSW Registry of Birth, Deaths and Marriages (RBDM) records details of deaths in NSW, such as name, date of birth, sex and the details recorded on the death certificate, such as date of death and cause(s) of death. NSW RBDM death records are fed into a national system for recording deaths for statistical purposes run by the Australian Bureau of Statistics (ABS), which produces an annual analysis of mortality for all of Australia and separately for each state and territory. Using record linkage between records in the NSW ADHC ID Service Register and records in the RBDM register, it possible to determine age- and sex-specific counts and rates of mortality for the cohort of persons with an intellectual disability, who have previously received a state-funded intellectual disability service. At the present time, this is the most comprehensive way of obtaining representative data on mortality in people with an intellectual disability in Australia.
Methodology The present study examines mortality in people with an intellectual disability residing in the state of NSW, Australia, for the period 1st June 2005 to 31st December 2011 (6.59 years). The population of NSW in 2011 was estimated to be 7 218 529, and in 2006, it was estimated to be 6 742 690 (ABS 2014a).
385
performed by the NSW Centre for Health Record Linkage (CHeReL), using de-identified record linkage, based upon an SLK581 Statistical Linkage Key (Karmel 2005). Linkage of the RBDM to the intellectual disability cohort identified 953 death records of people with an intellectual disability who had died between 1 June 2005 and 31 December 2011. Peculiarly, the linkage found six deaths occurring in June 2005, the month before the intellectual disability cohort was formed from persons registered in the 2005/ 2006 to 2011/2012 financial years. A person is registered once per financial year, if they receive any service during that financial year. The operation of the register is that at the beginning of each financial year, clients receiving a block-funded regular service are automatically rolled over into the next financial year. For this reason, six deaths in June 2005 were captured by the linkage, because though these people had died late in the 2004/2005 financial year, they were still registered in the 2005/2006 financial year because their place in a block-funded regular service was still allocated to them early in the 2005/2006 financial year, until ADHC became aware that they had died and allocated the place to someone else.
Calculation of person-years for the intellectual disability cohort Person-days of exposure, partitioned into five-year age groups, were calculated for each individual using 1st June 2005 or date of birth, whichever occurred last, as a starting date and 31st December 2011 or date of death (in the case of those that died) as an end date. To convert to personyears, person-days were divided by 365.25. Collectively, the 42 219 persons in the intellectual disability cohort accumulated 270 649 person-years of exposure over the 6.59 years of observation.
Intellectual disability (ID) cohort A cohort of people with an intellectual disability residing in NSW (intellectual disability cohort) was formed from the NSW ADHC ID Service Register covering all persons registered to receive a service in the seven financial years (July 1 to June 30) starting on 1 July 2005 and ending 30 June 2012. This created a cohort of 42 219 persons aged from
Journal of Applied Research in Intellectual Disabilities 2015, 28, 383–393
Mortality among a Cohort of Persons with an Intellectual Disability in New South Wales, Australia Tony Florio*,† and Julian Trollor† *School of Psychological Sciences, Australian College of Applied Psychology (ACAP), Sydney, NSW, Australia; †Department of Developmental Disability Neuropsychiatry, UNSW, Sydney, NSW, Australia
Accepted for publication 22 April 2015
Objectives The main objective of the study was to compare mortality for people with an intellectual disability (ID) to the general population in New South Wales (NSW), Australia. A second objective was to provide mortality data for people with an intellectual disability from NSW in a standardized format, which allows for international comparisons of the mortality of people with an intellectual disability. Design and setting The study was a longitudinal cohort study linking retrospective data from the population databases of the NSW Department of Ageing, Disability and Home Care (ADHC) Intellectual Disability Services Dataset (intellectual disability cohort) to the mortality data set of the NSW Registry of Births, Deaths and Marriages (RBDM) for the period 1 June 2005 to 31 December 2011. Participants The two groups of interest for this study were persons with an intellectual disability recorded in the intellectual disability cohort (953 deaths among 42 219 persons over 270 649 person-years of observation) and the rest of the NSW population (312 649 deaths among over 7 218 529 persons [2011 population] and 45 818 946 person-years of observation). Main outcome measures In this study, we compared the intellectual disability cohort with the rest of the NSW population using age-adjusted death rates (ADRs), standardized mortality ratios (SMRs) and age standardized
Background The mortality of persons with an intellectual disability (ID) is higher than that of the general population (Patja et al. 2000; Bittles et al. 2002; Durvasula et al. 2002; Tyrer et al. 2007; Heslop et al. 2013). At a population level, © 2015 John Wiley & Sons Ltd
death rates (ASDRs) based upon the World Health Organization (WHO) standard population. Results We found a significantly higher mortality in a cohort of people with an intellectual disability compared to the rest of the NSW population. The intellectual disability cohort compared to the rest of the NSW population had an SMR of 2.48 for all ages and an SMR of 3.15 for those aged 5–69 years. We also found an SMR for females (4.26) with an intellectual disability that was significantly higher than that for males (2.52) with an intellectual disability. The ASDR for the intellectual disability cohort was 4.04 (deaths per 1000) and the ASDR for the rest of the NSW population was 1.58, giving a comparative mortality ratio of 2.55. Conclusions Our findings indicate excess mortality of people with an intellectual disability when compared to the general population. They also indicate that females with an intellectual disability have a higher relative mortality compared to female same-aged general population peers, and also males with an intellectual disability, a finding replicated in other similar cohort studies. For international comparison using the WHO standard population, our intellectual disability cohort (ages 5–69 years) had a mortality of 4.04 deaths per 1000. Keywords: Australia, cohort studies, disabilities, mortality, record linkage
intellectual
numerous factors operate to bring about this excess mortality: greater comorbidity of intellectual disability with other health conditions that have a high mortality (Forsgren et al. 1996; Bittles et al. 2007; Heslop et al. 2013), poorer access to appropriate health care (Beange et al. 1995), polypharmacy (Heslop et al. 2013), greater 10.1111/jar.12190
384 Journal of Applied Research in Intellectual Disabilities
engagement in lifestyles that promote and/or exacerbate illness (Beange & McKerras 1994), social and financial disadvantage (Emerson et al. 2007; Emerson 2012) and a lack of health self-care which is not corrected by formal and informal support (Beange et al. 1995). The relative excess mortality of people with an intellectual disability compared to their peers in any particular population is a function of the mixed operation of such factors over periods of time in that population. A first step in addressing the excess mortality for people with an intellectual disability, in a particular population, is to be able to quantify, measure and study the absolute and comparative mortality of people with an intellectual disability in ways that might provide new information that can be applied to mitigate specific factors which contribute to excess mortality in that population. Another strategy is to compare the rates of excess mortality of people with an intellectual disability between jurisdictions. International comparisons, in particular, have the potential to be highly informative. Systematic examination of rates of excess mortality of people with an intellectual disability, in different countries with known differences in some of the factors that can contribute to excess mortality, could provide valuable insights. Alternately, different countries with known rates of excess intellectual disability mortality can be compared for differences in factors which might account for the observed differences in excess intellectual disability mortality. The main objective of this study was to compare mortality for people with an intellectual disability to the general population in NSW, Australia, to measure the differential mortality of people with an intellectual disability. It is expected that people with an intellectual disability will have excess mortality compared to their population peers. A second objective was to provide mortality data for people with an intellectual disability from NSW in a standardized format, which allows for international and interstate comparisons of the mortality of people with an intellectual disability, between NSW, Australia, and elsewhere.
The Australian and New South Wales context Australia is an island continent country with a current population of over 23 million persons. Australia is a federation consisting of six states and two territories. The most populous state is New South Wales (NSW) with a current population of over 7.5 m. More than 85% of Australians live in urban areas and nearly 70% live in a state or territory capital city, making Australia one of the most urbanized countries in the world. The median
age in 2011 was 37 years, 14% of the population was aged over 65 years, life expectancy for a male at birth was 79.9 years and for a female 83.4 years, the crude death rate was 6.5 per 1000 of population, the sex ratio was balanced with 99 males for every 100 females, and the fertility rate was 1.9 babies per woman of child bearing age. Over one in four Australians (27%) were born outside of Australia, with migrants (the largest source of population growth for Australia) coming from many different parts of the world (most recently mainly from Asia), creating an ethnically diverse population. Indigenous Australians, also known as Aboriginal and Torres Strait Islanders, make up almost 3% of the population. All the above figures are from ABS (2014a). Australia has a substantial history of providing statefunded services to people with an intellectual disability. Prior to the mid-1980s, these services consisted almost entirely of large institutional residential services. A series of reforms since the 1980s has brought about a more diverse range of community-based services, which includes community-based group homes, developmental assessment services, early intervention services, respite group homes, community support teams, therapy (physiotherapists, occupational therapists and speech pathologists) and behavioural intervention services. The vestiges of large residential institutions still remain in a much diminished form, but are now a minor component compared to community-based services. At the current time, Australia is in transition from state-funded/ provided services to the provision of services under a National Disability Insurance Scheme. The hallmark of this scheme is individualized funding for the purchase of services in an insurance model in which federal and state governments pay an annual premium for the whole population. Individuals with a disability apply for and are funded to purchase services of their choice from a set of registered service providers. The announced timetable is that full transition will be completed by 2018, but it may prove to take longer. A consequence of the historical state funding of services to people with an intellectual disability is that administrative records have been kept by government departments for the purposes of managing these services. In the case of NSW, the largest state in Australia, the Ageing, Disability and Home Care (ADHC) branch of the NSW Department of Family & Community Services (FACS) has collected and electronically maintained records of persons who receive an intellectual disability service. As such, there exists an electronic register (dating back from the present to 2005) containing details of people of all ages, who are known to have an intellectual disability. © 2015 John Wiley & Sons Ltd, 28, 383–393
Journal of Applied Research in Intellectual Disabilities
To receive an intellectual disability service (and be placed on the register), a person undergoes an eligibility assessment conducted by a registered psychologist, which determines that the person meets the DSM-IV criteria for intellectual disability. Thus, the NSW ADHC administrative ID Service Register forms the basis for defining a cohort of persons with an intellectual disability. In NSW, the NSW Registry of Birth, Deaths and Marriages (RBDM) records details of deaths in NSW, such as name, date of birth, sex and the details recorded on the death certificate, such as date of death and cause(s) of death. NSW RBDM death records are fed into a national system for recording deaths for statistical purposes run by the Australian Bureau of Statistics (ABS), which produces an annual analysis of mortality for all of Australia and separately for each state and territory. Using record linkage between records in the NSW ADHC ID Service Register and records in the RBDM register, it possible to determine age- and sex-specific counts and rates of mortality for the cohort of persons with an intellectual disability, who have previously received a state-funded intellectual disability service. At the present time, this is the most comprehensive way of obtaining representative data on mortality in people with an intellectual disability in Australia.
Methodology The present study examines mortality in people with an intellectual disability residing in the state of NSW, Australia, for the period 1st June 2005 to 31st December 2011 (6.59 years). The population of NSW in 2011 was estimated to be 7 218 529, and in 2006, it was estimated to be 6 742 690 (ABS 2014a).
385
performed by the NSW Centre for Health Record Linkage (CHeReL), using de-identified record linkage, based upon an SLK581 Statistical Linkage Key (Karmel 2005). Linkage of the RBDM to the intellectual disability cohort identified 953 death records of people with an intellectual disability who had died between 1 June 2005 and 31 December 2011. Peculiarly, the linkage found six deaths occurring in June 2005, the month before the intellectual disability cohort was formed from persons registered in the 2005/ 2006 to 2011/2012 financial years. A person is registered once per financial year, if they receive any service during that financial year. The operation of the register is that at the beginning of each financial year, clients receiving a block-funded regular service are automatically rolled over into the next financial year. For this reason, six deaths in June 2005 were captured by the linkage, because though these people had died late in the 2004/2005 financial year, they were still registered in the 2005/2006 financial year because their place in a block-funded regular service was still allocated to them early in the 2005/2006 financial year, until ADHC became aware that they had died and allocated the place to someone else.
Calculation of person-years for the intellectual disability cohort Person-days of exposure, partitioned into five-year age groups, were calculated for each individual using 1st June 2005 or date of birth, whichever occurred last, as a starting date and 31st December 2011 or date of death (in the case of those that died) as an end date. To convert to personyears, person-days were divided by 365.25. Collectively, the 42 219 persons in the intellectual disability cohort accumulated 270 649 person-years of exposure over the 6.59 years of observation.
Intellectual disability (ID) cohort A cohort of people with an intellectual disability residing in NSW (intellectual disability cohort) was formed from the NSW ADHC ID Service Register covering all persons registered to receive a service in the seven financial years (July 1 to June 30) starting on 1 July 2005 and ending 30 June 2012. This created a cohort of 42 219 persons aged from
