Trends in the prevalence of disability and chronic conditions: implications for survey design and measure of disability.

Presented by Xingyan WenAustralian Institute of Health and Welfare

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Recent trends in disability prevalence

Decline in disability prevalence: United States, Germany, France and Japan.

Mixed patterns of prevalence: Canada

No consistent decline: the United Kingdom and Netherlands

No decline and a possible increase: Australia

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Recent trends in the prevalence of chronic conditions The reported decline in disability rates in some

OECD countries was accompanied by an increase in the reported prevalence of chronic conditions (eg. the United States and France).

This increase was also reported in countries where no consistent decline in disability or a possible increase in disability was reported (eg. Australia).

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Issues in measuring disability and monitoring trends in disability prevalence

Why has a decline in disability prevalence been accompanied by an increase in the prevalence of chronic diseases in some developed countries?

Why have different trends (increases and decreases) in disability prevalence been reported among the OECD countries?

Could the trends in disability within each country be compared internationally on the basis of the existing survey data?

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Some explanations of the issues The increases in chronic conditions are largely

conditions that are less severe or less debilitating. The advance in medicine and health care services

contributed to a slowing down in the rate of progression of chronic diseases or less serious consequences.

The increases in transition from diseases into functional limitations or need for help with daily activities are not necessarily the same as the increase in the prevalence of chronic diseases.

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Remaining important issues The explanations of the issues are far from

adequate Decline mainly occurred in less severe

disabilities. Variations in survey measures and their impact

on cross-nation comparison of trends in disability prevalence.

It is useful to make a comparison of the United States and Australia

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Trends in disability prevalence in the United States (Schoeni et al. 2001)

There were clear declines in disability prevalence in 1982-1986, but no improvements during 1986-1992.

Disability began to decline again more modestly around 1992, falling through 1996 (the last year of available data).

Only ‘routine care’ disability has declined but not more ‘severe personal care’ disability.

The evidence is fairly consistent across five US national surveys.

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Trends in disability prevalence, Australia, 1981-1998

Severe/ profound restriction Specific restrictions

65+ All ages 65+ All ages

1981 16.2 3.9 32.9 10.7

1988 17.9 4.3 45.1 14.6

1993 17.1 4.3 44.6 14.3

1998 19.6 5.5 45.5 16.1

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A comparison of the operational definitions of disability Screening questions in US surveys: activity

limitations (ADLs and IADLs) Screening questions in Australia surveys:

impairments and long-term conditions restricting everyday activities

Increases in the prevalence of chronic conditions could have different impact on the reported prevalence of disability over time.

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A comparison of the operational definitions of disability (Continued)

Screens focusing on activity limitation only would not capture individuals using aids and appliances who did not report activity limitation.

Screens containing body function limitations could capture respondents who were using aids, even though they did not report activity limitation in subsequent survey questions.

An increase in the number of people using aids could have different impacts on the reported prevalence of disability over time.

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A comparison of the operational definitions of disability (Continued)

The ABS disability survey screens specify a limit of 6 months or more for inclusion of any disease, disorder, impairment and activity limitation.

Most US survey screens do not contain a duration limitation except for the National Long-term Care Survey (NLTCS) (90 days or more)

Inclusion of a duration limitation in the survey screens may assist in standardising the estimates of disability.

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Suggestions on general measures of disability At least two general measures:

One focuses on the activity/participation dimension(s) of the ICF and perhaps in addition an open-ended question on any long-term health conditions limiting everyday activities.

Another focuses on the body function dimension of the ICF.

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Why at least two general measures? To increase the international comparability of

disability data To capture individuals who use aids due to

functional problems but with no difficulty in activity when using aids.

To capture individuals who receive assistance with activities and report no difficulty in activities due to the assistance.

To capture individuals with a condition restricting participation but not activities.

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Suggestions on general measures of disability Focusing on long-term disabilities:

to reduce the large variations in the estimates that include short-term problems

to increase the comparability Focusing on severe disability:

Relatively stable over time less likely to be affected by changes in

perceptions and attitudes ICF has a conceptual framework in which these

issues may be discussed.