Psychiatric and substance abuse disorder diagnoses as predictors of length of hospital stay

Abstract

The mental health and substance abuse components of AN-DRG 3 were examinedusing data from all inpatient separations in two Australian States over a two-yearperiod. Assignment to a mental health or a substance abuse diagnosis related group(DRG) predicted about 20- per cent of the variability in average length of stay ofpatients treated for such conditions. Assignment to a substance abuse DRG was amuch less robust predictor of length of hospital stay than assignment to a mental healthDRG. There was little variation between years or States. Day-only intent patientswere excluded, as were long-stay outliers identified using an inter-quartile rangetrimming process. Psychiatric DRGs are similar to a number of other non-surgicallyfocused diagnosis related groups in their capacity to predict length of hospital stay. Theyare likely to remain an important component of casemix classification systems.