PATTERNS OF LENGTH OF STAY AFTER ADMISSION IN GERIATRIC-MEDICINE - AN EVENT HISTORY APPROACH

Previous work has indicated that a two-term mixed exponential distribution gives a good fit to data on lengths of stay of patients in departments of geriatric medicine. A database on the lengths of stay of patients entering a department, and their subsequent destinations, over a 16-year period, is used to examine the pattern of length of stay in ward of admission until death, discharge or transfer. The two-term mixed exponential distribution is fitted to these data using death/discharge and transfer as the two components of the mixture in order to assess to what extent the previous success of this distribution for census data may be explained by our current longitudinal data and choice of components. The model is then extended to the more sophisticated mixed exponential and log-normal distribution which better enables us to capture the exact shape of the distribution.