Performance of APACHE III over time in Australia and New Zealand: a retrospective cohort study

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Abstract

The Acute Physiology and Chronic Health Evaluation (APACHE) III-j model has been used for benchmarking intensive care unit (ICU) outcomes in Australia and New Zealand for over a decade. This study assessed performance of the APACHE III-j model in adult patients admitted to Australasian ICUs during a ten-year period. Data were extracted from the Australian and New Zealand Intensive Care Society Adult Patient Database. Performance of APACHE III-j at different time points and within different age strata was evaluated by dividing the whole cohort into five two-year groups. Calibration and discrimination were assessed by the Brier score, Hosmer-Lemeshow C and H statistics, Standardised Mortality Ratio (SMR), Cox calibration regression, calibration curves and area under the receiver operating characteristic curve (AUROC). Model performance within diagnostic categories was evaluated. Between 1 January 2000 and 31 December 2009, 558,585 ICU admissions which met inclusion criteria were included in the analysis. The mean (standard deviation) age was 60.8 (18.4) years and 58.3 were male. Overall observed mortality was 12.6 . The mean (standard deviation) APACHE III-j predicted mortality was 14.5 (21.8). Although discrimination (as measured by AUROC) was preserved over time, all other markers of model performance showed deterioration. There was a significant decrease in SMR in eight of ten most common diagnoses examined. This study demonstrates that performance of APACHE III-j model has deteriorated in Australasian hospitals and there is now a clear need for an updated modelling approach to improve mortality prediction, performance monitoring and quality of research undertaken in Australian and New Zealand ICUs.
Original languageEnglish
Pages (from-to)980 - 994
Number of pages15
JournalAnaesthesia and Intensive Care
Volume40
Issue number6
Publication statusPublished - 2012

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