Concurrent prediction of hospital mortality and length of stay from risk factors on admission.
OBJECTIVE
To develop a method for predicting concurrently both hospital survival and length of stay (LOS) for seriously ill or injured patients, with particular attention to the competing risks of death or discharge alive as determinants of LOS.


METHODS
Previously collected 1995-1996 registry data on 2,646 cases of injured patients from three trauma centers in Maine.


METHODS
Time intervals were determined for which the rates of discharge or death were relatively constant. Poisson regression was used to develop a model for each type of terminal event, with risk factors on admission contributing proportionately to the subsequent rates for each outcome in each interval. Mean LOS and cumulative survival were calculated from a combination of the resulting piecewise exponential models.


RESULTS
Age, Glasgow Coma Scale, Abbreviated Injury Scores, and specific mechanisms of injury were significant predictors of the rates of death and discharge, with effects that were variable in different time intervals. Predicted probability of survival and mean LOS from the model were similar to actual values for categorized patient groups.


CONCLUSIONS
Piecewise exponential models may be useful in predicting LOS, especially if determinants of mortality are separated from determinants of discharge alive.
Department of Surgery, Maine Medical Center, Portland 04102, USA.
David E
DE
Clark
Louise M
LM
Ryan
D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D015601:Injury Severity Score; D007902:Length of Stay / Q000706:statistics & numerical data*; D008281:Maine / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data*; D010351:Patient Discharge / Q000706:statistics & numerical data*; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013997:Time Factors; D014193:Trauma Centers / Q000706:statistics & numerical data*; D015599:Trauma Severity Indices; D014947:Wounds and Injuries / Q000401:mortality*