Modelling future disability service demand in Wyndham

One of the most common questions we are asked at training sessions is “Do you have any information on disability?”. There is some information in the Census, on Need For Assistance, but it’s fairly basic, just a Yes/No response designed to measure severe or profound disability. Nationally, 4.6% of the population answered “Yes” to this question, and it is highly skewed towards the older age groups as you would expect.

The City of Wyndham approached .id to do some modelling, to estimate the likely current demand for aged and disability services in their municipality, and importantly the likely future need.

The City of Wyndham is one of Australia’s fastest growing areas. Located on Melbourne’s western fringe, it has a booming first home buyer market, due to relatively affordable housing, and plenty of land zoned for future housing growth. Young couples and families are moving there in large numbers. The population doubled between 2003 (95,000 people) and 2013 (190,000 people), and .id’s forecasts show a further doubling to 384,000 by 2036, at which time it will be one of the largest LGAs in Australia.

But as with many growth areas, it’s not all about growth. Areas of Wyndham which have developed over the past 30 years are now ageing, and, while the age profile is currently quite young, the over 65s will grow at a faster rate than the rest of the population over the next 20 years. Wyndham is also a highly diverse area, with the Non-English Speaking Background population rising from 17% of population in 2006 to 25% in 2011, a huge increase driven by Indian, Chinese, Burmese and Filipino migrants. These groups also have very different age structures and need for assistance rates.

Against this backdrop, the City of Wyndham is conducting a review of aged and disability care in the area, including in-home services, transport and mobility services, case management, respite support, property maintenance and Metro Access.

The demographic component of this review has now been completed with some interesting findings. As part of this, Wyndham have subscribed to the new Communities of Interest module for profile.id, which shows, among other things, that the people with a need for assistance in Wyndham are more likely to live in households with children at home, and much more likely to live in households with a mortgage than across Melbourne (there is also a large contingent of those aged 65+ in private rental accommodation, a highly vulnerable group).

The Census shows 5,441 people with a need for assistance in Wyndham. While this is a lower percentage (3.4% to 4.5%) than the Melbourne average, this chart shows that it’s distributed very differently, with substantially higher rates of need at every age group – it’s only lower because Wyndham’s age structure is so much younger than the Greater Melbourne area overall.

So what the council really wanted to know is, “What will our future rate of need for assistance be?”

For this we enlisted the help of the ABS Survey of Disability, Ageing and Carers (4430.0).  Last run in 2012, this survey contains a wealth of information about types of disability, duration of disability and need for assistance, broken down at a national level by various demographic characteristics, like age, cultural group, education etc. Because it’s an interviewer based survey, it can ask a lot more detailed questions, and has a good response rate, like most ABS surveys. The downside is that because it only samples a small number of people in any given area, it can’t produce meaningful data for Local Government Areas, or indeed any geography below state level.

However, because it does have so many demographic characteristics, the Survey lends itself to using Census and forecast data to model this to a small area. Using the national propensities by age and sex, combined with the forecast age and sex data in Wyndham’s forecast.id site, we were able to estimate the number of people in 2014, 2024 and 2034 (20 years from now) with various types of need for assistance. The Survey has an age breakdown for each disability type – as follows. For instance, the need for assistance with communication activities has a much younger age profile than mobility.

We then applied the specific Census ratios – remember Wyndham has a higher rate in almost every age group, according to the Census – to account for the local difference in age propensities from the national average.

This gives an estimate for each type of disability of the number and proportion needing assistance, including multiple types.

The modelling shows that over 17,000 people currently need assistance. This is much higher than the Census count, partly due to a difference in scope (the survey includes all need for assistance, while the Census is designed to measure those with a severe or profound disability), and partly due to a net undercount from the Census question. The most common forms of assistance needed are Self-Care and Oral Communication or Cognitive Tasks.

But the real interest is in the future. Due to the substantial population growth expected, and considerable ageing with it, most forms of disability are expected to more than double in 20 years, with the largest increase being among those needing help with their Household Chores or Property Maintenance.

This is not evenly spread through the City of Wyndham. Areas which developed through the 1970s and 1980s are currently ageing rapidly and have the largest proportion of need for assistance now. But current growth areas which are just finishing up, like Point Cook, currently full of families, will have the largest increase in those aged 65+ over the next 20 years, and as a result, the largest increase in people with a need for assistance.

This can help the council in locating their aged and disability care services in the future, within the council, and providing information to external providers about the likely demand for these services.

Forecast change in number of people with a need for assistance, City of Wyndham suburbs, 2014-2034

This type of basic modelling makes use of 3 data sources – The Survey of Disability, Ageing and Carers for national rates by demographic characteristics, the Census for local nuance of those characteristics, and .id’s suburb-level population forecasts for future change in those characteristics. The model draws these together to give councils an estimate of the likely demand for disability services in the future. This analysis can be done for any area in Australia, and can logically be extended to any survey data where detailed demographic data is included. This could include rates of dementia or other specific diseases, participation in sport and leisure activities, or even crime victimisation rates.

In the meantime, the City of Wyndham now has a firm evidence base for which to plan their future age and disability services.