Modelling In-Patient Bed Usage Behaviour in a Department of Geriatric Medicine

Abstract:

The flow of patients through geriatric hospitals has been previously described in terms of acute and long-stay states where the bed occupancy at a census point is modelled by a mixed exponential model. Using data for sixteen years the model was fitted to successive annual census points, in order to provide a description of temporal trends. While the number of acute patients has remained fairly stable during the period, the model shows that there has been a decrease in the number of long-stay patients. Mean lengths of stay in our geriatric hospital before death or discharge have decreased during the study period for both acute and long-stay patients.

Using these fits of the mixed exponential model to census data, a method is provided for predicting future turnover of patients. These predictions are reasonably good, except when the turnover patterns go through a period of flux in which assumption of stability no longer holds. Overall, a methodology is presented which relates census analysis to the behaviour of admission cohorts, thus producing a means of predicting future behaviour of patients and identifying where there is a change in patterns.

Key-words

Geriatric Medicine - Bed Occupancy - Patient Flow - Mixed Exponential Model

• REFERENCES

• 1 Harrison GW, Millard PH. Balancing acute and long term care: The mathematics of throughput in departments of geriatric medicine. Meth Inform Med 1991; 30: 221-8.
• 2 Millard PH. Throughput in a department of geriatric medicine: a problem of time, space and behaviour. Health Trends 1992; 24: 20-4.
• 3 Cox DR. Renewal Theory. London: Methuen; 1962
• 4 McClean SI, Gribbin JO. Estimation for incomplete manpower data. Appl Stoch Models and Data Anal 1987; 03: 13-25.