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Research articles · Apr 30, 2020

IDMOD: An Australian microsimulation model of lifetime economic and social factors in familial intellectual disability

Deborah J Schofield, Owen Tan, Rupendra N Shrestha, Radhika Rajkumar, Sarah West, Morgan Rice, Nadine Kasparian, Jackie Boyle, Louise Christie, Melanie Leffler, Lucinda Murray, Robert Tanton, Jinjing Li, Tony Roscioli, Michael Field

GenIMPACT: Centre for Economic Impacts of Genomic Medicine, Macquarie Business School, Macquarie University, North Ryde, Australia; Royal Prince Alfred Hospital, Camperdown, Australia; Heart Centre for Children, The Sydney Children’s Hospitals Network, Sydney, Australia; Discipline of Paediatrics, School of Women’s & Children’s Health, UNSW Medicine, The University of New South Wales, Sydney, Australia; Genetics of Learning Disability (GoLD) Service, Newcastle, Australia; National Centre for Social and Economic Modelling (NATSEM), Institute for Governance and Policy Analysis, University of Canberra, Bruce, Australia; Neuroscience Research Australia, University of New South Wales, Randwick, Australia; Sydney Children’s Hospital, Randwick, Australia

Volume 13(1) Spring 2020

Cite as: D. Schofield, O. Tan, R. Shrestha, R. Rajkumar, S. West, M. Rice, N. Kasparian, J. Boyle, L. Christie, M. Leffler, L. Murray, R. Tanton, J. Li, T. Roscioli, M. Field; 2020; IDMOD: An Australian microsimulation model of lifetime economic and social factors in familial intellectual disability; International Journal of Microsimulation; 13(1); 52–66. doi: 10.34196/ijm.00212

Abstract

Intellectual disability (ID) is associated with far reaching economic and psychosocial outcomes. People with ID require a wide range of supports from both governments, and families. No study has thoroughly assessed the economic and social costs of care for individuals with familial ID. Understanding the comprehensive costs of ID is important for policy makers to decide on resources required to support the families affected by the condition. In the Australian Economic and Psychosocial Impacts of Caring for Families Affected by Intellectual Disability (EPIC-ID Study), we developed a microsimulation model, IDMOD, to provide a holistic perspective of the economic costs of ID for use in cost-effectiveness studies related to genomic testing and precision medicine for familial ID. This paper describes the construction of IDMOD. The model base population are individuals who were referred to the Genetics of Learning Disability (GoLD) clinics. Through a detailed questionnaire, we collected information including health expenditure, income, education, welfare payments, savings, housing and residential care, and support received for purchase of aids and equipment, employment for both people with ID and their carers. Both government and patient costs were included. Data on quality of life, psychological wellbeing, relationship strength and social inclusion are also collected before and after genomic diagnostic testing. Patients’ use of medical services, prescription medicines, and hospital services were captured via linked datasets. Lost income, assets, and tax were imputed via synthetic matching to records from the Static Incomes Model (STINMOD). Each unit record in the model was weighted using input from the Survey of Disability, Ageing, and Carers (SDAC) to reflect the total familial ID population in Australia. The model will provide data on the economic costs of familial ID in Australia, and the associated effects of implementing genomic testing and precision medicine for this population group.

This article contains 2 figures and 3 tables.

Figures

Figure 1. Structure of IDMOD
Figure 2. Data collected from “retrospective” and “prospective” cohorts will be used to assess the lifetime burden associated with ID without the WGS, and with WGS, respectively.

Tables

Table 1. Services used, and costs data collected in the EPIC-ID questionnaire
Category Item Cost (annual unless specified otherwisea) Perspective Data source Note
Health system
Inpatient AR-DRG Government NSW Admitted Patient Data Collection
Emergency department URG Government NSW Emergency Department Data Collection
Outpatient consultation Government Medicare Benefits Schedule data
Naturopatha $107 per session OOP (Cancer Council Australia, 2018)
Prescription medication Government Pharmaceutical Benefits Scheme data
Supplements and OTC medication Self-reported OOP
Supported accommodation & respite
Residential care $16,973 Income and assets mean tested (no more than $$27,754 per year) Government (Australian Government Department of Health, 2017)
Residential care-basic daily fee $18,038 Government (Australian Government Department of Health, 2017) Basic daily fee is paid out of pocket for over 65 residents. Fee for under 65 disabled residents is covered by the NDIS.
Specialist Disability Accommodationa $4,452-$59,375 Government (National Disability Insurance Agency, 2017) Cost of accommodation is subject to patients’ needs (accessibility, on-site overnight assistance, or high level of physical access provision with high support need) and number of people sharing the accommodation.
Supported Independent Livinga $1,727-$4,951 per week Government (National Disability Insurance Agency, 2016) Cost of supported independent living depends on support needed to undertake household tasks and/or self-care activities.
Respite care $13,024 Government (Australian Institute of Health and Welfare, 2017)
Rent subsidy Market rent less 25%–30% of household income Government (Department of Communities and Justice NSW, 2019) Eligibility for government subsidy is income tested.
Welfare
Disability support pension (under 20 years and living independent) $13,335 Government (Australian Government Social Security Guide, 2018a)
Disability support pension (under 18 years and living at home) $8,104 Government (Australian Government Social Security Guide, 2018a)
Disability support pension (18–20 years and living at home) $9,393 Government (Australian Government Social Security Guide, 2018a)
Disability support pension (above 20 years old) $23,254 Government (Australian Government Social Security Guide, 2018a)
Mobility allowance standard rate $2,493 Government (Australian Government Social Security Guide, 2018b)
Mobility allowance higher rate $3,487 Government (Australian Government Social Security Guide, 2018b)
Supported employment $5,031 Government (Australian Institute of Health and Welfare, 2017)
Education
Primary student-Supplementary level support $16,107 Government (Department of Education, 2019)
Primary student-Substantial level support $27,903 Government (Department of Education, 2019)
Primary student-Extensive level support $46,733 Government (Department of Education, 2019)
Secondary student-Supplementary level support $18,958 Government (Department of Education, 2019)
Secondary student-Substantial level support $30,789 Government (Department of Education, 2019)
Secondary student-Extensive level support $49,604 Government (Department of Education, 2019)
Early intervention classa $185 per hour Government (National Disability Insurance Agency, 2018)
Aids and modifications Self-reported OOP/Government EPIC-ID questionnaire recorded costs and subsidies received for aids and modifications, including nappies, special diet, mobility aids (eg, wheelchair), lifting/hoisting apparatus, peg feeding equipment, visual, hearing and communication aids, orthotics, home modifications (eg, stairs, bedroom), and vehicle modifications.
Carer’s costs
Welfare (eg, carer payment, and carer allowance) Self-reported Government Carer payment and carer allowance are obtained from EPIC-ID questionnaire response.

AR-DRG = Australian Refined-Diagnosis Related Group; OOP = Out-of-pocket; OTC = Over-the-counter; URG = Urgency Related Group;

Costs that were not reported in the year of 2017 were adjusted at an inflation rate of 3% per annum.

Table 2. Example of education distribution in Australian Bureau of Statistics 2016 Census data
Age Sex State/Territory Highest qualification attained Proportion Upper bound Lower bound
25–29 years Male New South Wales Postgraduate degree, graduate diploma/graduate certificate 0.074 0.000 0.074
25–29 years Male New South Wales Bachelor degree 0.234 0.074 0.308
25–29 years Male New South Wales Advanced diploma/diploma 0.212 0.308 0.520
25–29 years Male New South Wales Certificate III / IV 0.079 0.520 0.598
25–29 years Male New South Wales Certificate I / II 0.001 0.598 0.599
25–29 years Male New South Wales Certificate not further defined 0.022 0.599 0.621
25–29 years Male New South Wales No non-school qualification 0.282 0.621 0.903
25–29 years Male New South Wales Level not determined 0.097 0.903 1.000
Table 3. National estimate of ID by severity, or by familial cause
Age group Number of people with ID recruited to date Number of moderate to severe ID in Australia (low estimate) Number of moderate to severe ID in Australia (high estimate) Number of mild ID in Australia (low estimate Number of mild ID in Australia (high estimate) Number of familial ID in Australia (low estimate) Number of familial ID in Australia (high estimate) Number of moderate to severe ID with familial cause (low estimate) Number of moderate to severe ID with familial cause (high estimate) Number of mild ID with familial cause (low estimate) Number of mild ID with familial cause (high estimate)
0–4 7 1,700 2,500 14,100 15,000 1,700 3,800 200 600 1,500 3,300
5–19 92 23,500 35,200 199,700 211,400 23,500 54,000 2,300 8,100 21,100 45,900
20–29 30 8,800 13,200 74,800 79,200 8,800 20,200 900 3,000 7,900 17,200
30–39 15 5,300 8,000 45,200 47,800 5,300 12,200 500 1,800 4,800 10,400
40–49 17 5,100 7,700 43,700 46,300 5,100 11,800 500 1,800 4,600 10,100
50–59 1 5,300 8,000 45,200 47,900 5,100 12,800 500 1,800 4,500 11,000
60–69 1 5,000 7,500 42,500 44,900 4,700 12,100 500 1,700 4,200 10,300