Professionals involved in planning and providing health and social services need a credible methodology supported by appropriate data. A modelling approach uses appropriately collected data to develop a mathematical model which enables us to understand the system, predict its future behavior, and investigate possible scenarios (McClean, 1994). In the Division of Geriatric Medicine at St. George's Hospital in London we have been developing and testing such a methodology in association with computer scientists and mathematicians in other universities. Part of the work presented in this paper was undertaken by May Ling Chang as part of her MSc in Decision Sciences at the University of Westminster, supervised by Dr. T. Chaussalet.
In 1995 the British Geriatrics Society used a spreadsheet model concerning the interaction of assessment and rehabilitation prior to long stay care to underpin their evidence to the IHouse of Commons Health Care Committee. The analysis indicated that the optimal approach was to introduce seven weeks pre-admission specialist rehabilitation so long as the new policy enabled 60 % of referred clients/ patients to be managed in their own homes (Millard and McClean, 1996).
Dementia and Its Care In England
The Population at Risk Figure 1 gives the prevalence ratios and expected number of dementia sufferers in England in 1991 by age group (65-69, 70-74. 75-79, 85+) and type (mild or advanced) of dementia (Hofman et al., 1991; Schneider et al., 1993).
Forecast Increases 1991-2031
Figure 2 shows the increase per age group expected in the number of cases of clinical dementia between 1991 and 2031.
Current Cost of Care
Table I gives the current estimated weekly cost of care for six forms of care as well as their average costs for both mild and advanced dementia. Data are 1991 estimates and were derived from two sources (Bowling and Farquhar, 1991: Schneider et al., 1993).
Historical Approach
In the historical approach there is no chief co-ordinator and a hodge podge of services is provided to dementia sufferers. A characteristic of this model is how many people are involved each adding to the burden of the informal network providing care. Denial of personal responsibility is also a characteristic of this model. The nearest semblance to any order is undertaken by the general psychiatrist, who may be overloaded simply because of the need to cope with many social workers each of whom has a generic case load. The social workers will also have difficulty in co-ordinating care because they have to cope with many different co-ordinating teams dealing with many different agencies.
Some elderly people with memory loss will visit general practitioners, some will not. Some general practitioners will investigate, others will not. Similarly, some will choose to refer to a consultant psychiatrist, others to a geriatrician. Chance dictates, coupled with the choice of the referring doctor, whether the consultant psychiatrist or geriatrician is, or is not, an investigatory one. Probably. neither will he be fully conversant, nor have access to the ...