Performance comparison in geriatric medicine: a study in one department

It is now commonplace to base performance comparison on productivity measurements. Yates recommended the use of Barber-Johnson diagrams to compare activity in acute specialties, but he did not commend their use in specialties with large numbers of beds and long lengths of stay. Performance comparison in geriatric medicine is difficult because factors such as the case mix and the discharge destination influence throughput. We used two mathematical models to compare the performance of five consultants in the same department. A Monte Carlo simulation based on historic-frequency tables indicated that the mean annual admissions to forty beds by the five consultants would vary between 592 and 748 admissions per year and a two-sample t-test indicated that only two of the consultants were the same, whereas the two-compartment flow model based on the average bed occupancy predicted the annual admissions to be between 650 and 856 and it indicated that the two consultants treated longer-stay patients differently. Thus the models identified differences in consultant performance which were not shown by simple statistics. The information required to decide if the variation in consultant performance is due to clinical or other differences is not yet routinely available. However, the benefit of modelling is that it identifies areas of variation and facilitates exploratory discussion.

A decision support system for bed-occupancy management and planning hospitals

The planning of services within a hospital is a complex task which relies on the availability of accurate data. Such data on patterns of bed occupancy enable us to develop tools which assess performance measures based on activity within a hospital and its beds, and hence they improve the efficiency of bed management and they facilitate the more effective use of resources. We report the development of a bed-occupancy-modelling package that uses a mathematical model to separate the pattern of bed occupancy in hospitals into acute, rehabilitative, and long-stay components. The bed-occupancy management and planning system analyses data downloaded from the patient administrative system. A query-by-example function is then used to separate the data into meaningful subgroups, such as age groups, or the various specialties. The underlying model is a mixed exponential where the number of terms in the mixture corresponds to the number of stages in the hospital spell, typically, acute, rehabilitative, and long stay. The software has been used to analyse data from a number of different specialties and services. A 'what-if' capability [correction of capacility] allows the planner to assess the effect of changes prior to their introduction.

Conflict of interest. Openness is not the only answer

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The St. George's dementia bed investigation study: a comparison of clinical and pathological diagnosis

Sixty-four elderly patients who had been admitted to the St. George's Hospital Alzheimer's disease evaluation project during 1981-1989 were followed up to postmortem examination. Comparison between clinical diagnoses and neuropathological diagnoses indicated positive predictive values for the antemortem diagnoses of 50-67%. Existing clinical criteria may not be accurate enough to permit firm antemortem diagnosis of older people for either research or clinical purposes.

Balancing acute and long-term care: the mathematics of throughput in departments of geriatric medicine

The empirical distribution of length of stay of patients in departments of geriatric medicine is fit extremely well by a sum of two exponentials. Most of the patients in a geriatric department are rehabilitated and discharged or they die within a few weeks of admission, but the few who become long-stay patients remain for months or even years. A model is presented for the flow of patients through a geriatric department, which has analogies to models of drug flow in pharmacokinetics. The theoretical model explains why the empirical pattern of length of stay in the occupied beds fits a sum of two exponentials; conversely, the empirical distribution, obtained from the midnight bed state report, can be used to study the effect of various policy decisions on both immediate and future admission rates for the department, and shows the benefits of policies which reduce long-stay patient numbers by improving long-stay rehabilitation.

Diagnosing dementia: do we get it right?

To find out whether the diagnosis of dementia agreed with findings at necropsy a detailed assessment of 27 elderly patients (mean age 82 (range 70-94] presenting with dementia was conducted at a combined department of geriatric medicine and psychiatry for the elderly. On the basis of the results the cause of the dementia was diagnosed clinically. Neuropathological examinations were performed after death. The clinical diagnosis made during life was not supported by the findings at necropsy in 11 cases. Alzheimer's disease was overdiagnosed in life (13 cases, of which only six were confirmed at necropsy). Although the clinical investigation was limited by availability of resources, neither cranial computed tomography nor the Hachinski score helped to distinguish between multi-infarct dementia and Alzheimer's disease in this age group. This study confirms the value of neuropathological studies in the precise diagnosis of dementia.

What is ageing?

The absolute numbers and proportion of elderly people within society is increasing and will continue to increase into the next century. An understanding of normal biology, physiology and anatomy of ageing are an essential prerequisite for the treatment of pathology in the elderly. Gerontology is a young scientific discipline where important developments are being made. Progress in increasing longevity has so far been limited, but continuing improvements in the quality of life for the elderly remain an attainable goal.