Department of Epidemiology & Public Health, School of Health Sciences, University of Newcastle
Centre for Health Services Research, School of Health Sciences, University of Newcastle, Newcastle-upon-Tyne, UK
Correspondence: P. McNamee, Department of Epidemiology & Public Health, School of Health Sciences, 21 Claremont Place, University of Newcastle, Newcastle-upon-Tyne NE2 4AA, UK
Declaration of interest None. Funding described in Acknowledgements.
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ABSTRACT |
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Aims To estimate the formal care costs associated with dementia in England and Wales between 1994 and 2031.
Method Epidemiological cost model, applied to individuals aged 65 years or over with dementia, using estimates of life expectancy with dementia and dementia-free life expectancy.
Results Total costs per year were £0.95 billion (men) and £5.35 billion (women) using 1994 population estimates. For 2031, costs were £2.34 billion and £11.20 billion, respectively. Reduced dementia prevalence rates and improvements in mental and physical functioning resulted in lower estimates: £1.01 billion (men) and £5.77 billion (women), and £1.65 billion (men) and £7.87 billion (women), respectively.
Conclusions Future increases in the population aged 65 years or over lead to rising formal care costs. However, the magnitude of cost changes depends on assumptions over dementia prevalence and levels of mental and physical functioning.
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INTRODUCTION |
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METHOD |
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Population projection, dementia prevalence and case definition
Population estimates were provided by national sources, which assume
reductions in future mortality (Office of
Population Censuses and Surveys, 1996a). Life expectancy
estimates were produced by extrapolating average age/gender-specific changes
during 1961-1991 to 2001-2031 (Office of
Population Censuses and Surveys, 1996b). Age- and
gender-specific prevalence rates were estimated using data collected in a
multi-centre study of four areas of England (Cambridgeshire, Newcastle,
Nottingham and Oxford) and one area in Wales (Gwynedd). Diagnosis of dementia
was made using the Geriatric Mental State (GMS version B3;
Copeland et al, 1976),
from which the Automated Geriatric Examination Computer Assisted Taxonomy
(AGECAT; Copeland et al,
1986) could be derived. Prevalence estimates were based on a level
of three or more on the organic section of AGECAT, which is approximately
equivalent to moderate (or more) clinical dementia. An age-stratified (65-74
years and 75 years) sample of 2500 individuals was selected randomly from
Family Health Services Authority or general practice files in the five
centres. Individuals in long-term hospital care were included because they
remain registered with their general practitioner (GP) for at least 2 years
after admission. A census of long-stay hospitals serving the catchment area of
the study populations identified less than 20 long-term residents not already
identified from GP lists. Further information on study design is reported
elsewhere (MRC CFAS,
1998).
Measurement of service use and costs
Service use and cost data were collected in a 5-year longitudinal Resource
Implications Study (RIS), part of the previous multi-centre study. Methods of
data collection and unit cost estimation are described in a separate paper
(McNamee et al,
1999). Briefly, however, data relating to the frequency and/or
duration of subjects' use of health care and personal social services over 2
years or until death (whichever was earlier) were collected by fieldworkers at
regular intervals using local records between 1991 and 1995. Subjects included
people living in private households or resident in long-term care. The
services costed were in-patient stays, out-patient visits, residential home
care, nursing home care, domiciliary home care, day care, day hospital care,
district nursing, sitting services, meals on wheels, respite care, GP care,
chiropody, community psychiatric nurse care, physiotherapy, social work care,
occupational therapy, health visitor care and laundry and incontinence
services.
The epidemiological cost model
Assumptions and methods of calculation are featured in
Table 1. Estimation required
five stages: first, the total number of years lived for each cohort (Y) was
calculated by taking the difference between the product of life expectancy
(LE) and the total number of survivors of successive cohorts; second, the
number of years lived with dementia (YD) for each cohort was calculated by
taking the product of the total number of years lived (Y) and the
cohort-specific dementia prevalence rate; third, DFLE was calculated by
subtracting the number of years lived with dementia (YD) from the total
remaining number of years lived (Y), followed by division of the total number
of dementia-free years (YYD) by the total population alive at the
beginning of each cohort; fourth, cohort-specific LEWD per person was
estimated by subtracting the DFLE from the remaining life expectancy (LE); and
finally, cohort-specific care costs per year were applied to each cohort's
LEWD, which was then multiplied by the total number of people with dementia
for that cohort, to produce aggregate estimates of cohort-specific care
costs.
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Cost projections to 2031
To extrapolate costs to four different periods between 2001 and 2031,
different population and life expectancy values were used, which were provided
by national sources (Office of Population Censuses and Surveys,
1996a,b)
holding age/gender-specific prevalence rates, service utilisation and costs
constant. The effects of these assumptions on the results were tested by
specifying different prevalence rates and levels of service utilisation. In
the absence of clear evidence on age- and gender-specific time trends,
analysis was conducted to determine the required change in prevalence rates in
order to produce constant costs over time.
To determine factors associated with service use and costs, two separate multivariate analyses were undertaken. For individuals in their own homes, the log of the total cost was used as the dependent variable in a multiple regression analysis. For the total study sample, logistic regression was undertaken to explore the relationship between residence in long-term care and a range of covariates (see Table 2). Parameter estimates from these models were used to determine the effects of changes in service utilisation on cost projections.
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RESULTS |
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Effects of changes in dementia prevalence rates on costs
In order to keep costs approximately constant, future dementia prevalence
rates would need to decline smoothly over each decade by 0.5%, 1% and 2% for
people aged 75-79 years, 80-84 years and 85 years or over, respectively. The
effects on costs resulting from this level of changing prevalence for those
aged 75 years or over are shown in Table
3, along with the effects of a similar increase in prevalence. An
increase was shown to lead to greater divergence from base case estimates over
time. Decreases in prevalence led to relatively stable costs of £91-77
million (£773-760 million), £211-197 million (£1840-1950
million) and £391-381 million (£2630-2780 million) for men (women)
over the period 2001-2031, respectively. Increases in prevalence produced
steadily increasing costs of £132-372 million (£1030-2450
million), £315-1060 million (£2450-6340 million) and
£589-2160 million (£3520-9210 million) for men (women) over the
period 2001-2031, respectively.
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The implications of reductions in prevalence are also highlighted in Fig. 1, showing that sustained reduction in prevalence among the group aged 75 years or over are required to ensure that costs remain similar to 1994 levels. Similar increases in prevalence increase the total costs year-on-year, rising to £4.26 billion and £18.5 billion by 2031 for men and women aged 65 years or over, respectively (not shown in Fig. 1).
Effects of changes in health status on service use and costs
Multiple regression analysis demonstrated that levels of mental and
physical functioning, measured by the Mini-Mental State Examination (MMSE;
Folstein et al, 1975)
and the Activities of Daily Living Score (ADL;
Bond & Carstairs, 1982),
were the factors most significantly associated (adjusted
R2=25%, F=31.3, d.f.=181; P<0.0001)
with variation in expected log costs per week. The regression estimate was:
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In other words, for each one-point increase in ADL and MMSE score, the data suggest that predicted log average weekly costs decrease by 15% and 9%, respectively.
The probability of living in long-term care (LTC) was related significantly
to mental and physical health, and was calculated as:
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These equations were used with age/gender-specific sample means for ADL, MMSE, community and long-term care costs to estimate the effect on costs of changes in ADL and MMSE. Projecting these changes through 2001-2031, using an assumption that ADL and MMSE both improve smoothly by 0.5 per decade, Fig. 1 depicts the effect on costs. Compared with the baseline, costs are shown to rise but at a much slower rate. In particular, costs for women remain reasonably stable through 2001-2021 but rise steeply thereafter to £7.87 billion in 2031.
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DISCUSSION |
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Three previous estimates of DFLE for the UK have been reported. Compared with estimates produced in this paper, LEWD was lower in Liverpool and Cambridge (Jagger et al, 1998), whereas in Melton Mowbray it was higher (Bone et al, 1995). One explanation for these differences relates to study design in the diagnosis of dementia. In the case of Liverpool, case definition was made at the screening phase, which led to different assumptions with respect to missing data. This resulted in lower prevalence estimates across all age groups for both genders. For Melton Mowbray, estimates were made inclusive of mild dementia, which led to higher prevalence and dementia life-year estimates. The lower Cambridge estimate is more difficult to explain, because this relates to earlier work conducted in one of the centres using the same study design. The most likely cause relates to low prevalence for a number of vascular problems (MRC CFAS, 1998).
Assumptions of the epidemiological cost model
Our baseline projections of formal care costs reveal that, considering only
changes in the number of older people, the percentage increase in total costs
can be expected to outstrip the percentage increase in the total number of
older people. However, this finding is dependent on assumptions made about
prevalence rates and levels of mental and physical health. The precision of
the five centre prevalence rates used in the baseline estimates is unknown
because no published confidence intervals are available. However, prevalence
estimates for this sample show the same relationship with age and are within
the range of estimates produced by other comparable studies
(Kay, 1995).
The relative impact of different assumptions on the results was explored, although the plausibility of the selected ranges requires comment. With respect to prevalence rates, no apparent upward or downward trend over time is noted in the literature. We therefore determined what rates were required to produce approximately constant costs given a projected increase in population size. As such, their plausibility can be tested only empirically. As a result of reported trends (Manton et al, 1997), improvement in physical health over time is perhaps more likely than sustained changes in prevalence. Such changes also could lead to better cognitive functioning, which could be facilitated by development of new drug therapies. Ultimately, however, exercises of this type are speculative and are conducted in order to test the extent to which baseline estimates change in relation to the magnitude of changes in assumptions.
Related to the above point, it is important to note that projections are based on national life tables adjusted for future decreases in mortality. It has been shown elsewhere that population growth usually is underestimated, especially at higher ages (Ritchie et al, 1994). If all else remains equal, this is likely to mean that our estimates are conservative.
Future changes in dementia prevalence, health status, service use and
costs
The baseline estimate projects that costs will amount to £13.5
billion in 2031 at 1994/1995 prices. Because evidence of changes in prevalence
and incidence over time is contradictory
(Kokmen et al, 1993), the effects of both upward and downward trends were modelled. It is apparent,
however, that evidence of the beneficial effect of time spent in formal
education and the development of dementia
(Katzman, 1993), together with
reductions in vascular and cerebrovascular risk factors
(Skoog et al, 1996),
suggests that the underlying trend could be downward. However, prediction of
whether changes in risk factors and incidence will produce changes in
prevalence depends on trends in survival times.
An equally important source of change is likely to relate to changes in age-specific utilisation rates of formal care, particularly care in residential and nursing homes. Logistic regression demonstrated that subjects in long-term care were more likely to have poorer mental and physical health. Improvements in physical health among older people over time have been demonstrated elsewhere (Bone et al, 1995; Manton et al, 1997) and could be expected to reduce the probability of admission to long-term care. Equally, however, other changes in the structure of the population might be expected to reduce the supply of non-spouse carers (Allen & Perkins, 1995). In addition, there is some evidence that admission to long-term care has shown an increasing trend over recent years (Grundy & Glaser, 1997).
Future sustainability of public funding for the care of frail older
people
As highlighted by the Royal Commission on Long Term Care
(1999), a key policy question
is whether growing numbers of frail older people relative to the size of the
labour force might require changes in the proportion of public v.
private financing of health and social care. To assess this issue, a number of
factors likely to exhibit change over time need to be considered.
First, it is apparent that reasonably small reductions in prevalence rates year-on-year would be required to produce an equivalent ratio between the population of working age and the number of people with dementia aged 65 years or over in 2031 compared with 1994. Based on a working age population of 30.3 million and 12.6 million people aged 65 years or over in 2031 (Office of Population Censuses and Surveys, 1996a), the overall dementia prevalence rate would have to reduce by 2.5% (equivalent to 0.06-0.07% per annum) to 4.1% in the population aged 65 years or over.
A further factor to consider is that age at death may be associated negatively with expenditure (Lubitz et al, 1995). Age at death has been increasing in developed countries (Wilmoth, 1997). It will be important to monitor these changes to assess the implications for projections in healthy life expectancies and health-care expenditure.
Finally, the above projections are necessarily partial in nature. The health and health-care implications of population ageing can be expected to have wider effects on the economy, such as levels of saving, which can be expected to influence rates of economic growth (Disney, 1996). Studies considering such relationships therefore are required to assess the capacity of the economy to provide current levels of formal care support in the future.
The effects of ageing on an age-related disorder such as dementia are likely to increase health and personal social service costs, but the level of such an increase is related to a wide range of demographic and economic factors. Given the current level of uncertainty, it would be unwise to make apocalyptic judgements regarding the effects of ageing in general, and dementia in particular, on health-care expenditure.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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REFERENCES |
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Received for publication August 16, 2000. Revision received January 24, 2001. Accepted for publication February 9, 2001.
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