Table 2.

The discriminating ability of the admission Acute Physiology and Chronic Health Evaluation (APACHE) II model and the worst 24-hour APACHE II model to predict inhospital mortality in different diagnostic and patient subgroups

Different diagnostic and patient subgroups	Number of patients	Mean area under the ROC curve (%) (95% confidence interval)a		Standardised mortality ratio (95% confidence interval)
		Admission model	Worst 24-hour model	Admission model	Worst 24-hour model
Sepsis, pneumonia, gastrointestinal perforation or obstruction	1,474	68.3 (65.4–71.3)	68.5 (65.6–71.4)	0.94 (0.90–0.98)	0.77 (0.75–0.80)
Intracranial, subdural or subarachnoid haemorrhage	851	79.5 (76.3–82.7)	80.4 (77.2–83.5)	1.29 (1.22–1.36)	1.03 (0.98–1.08)
Multiple trauma	1,299	87.0 (84.1–89.9)	87.3 (84.4–90.1)	1.73 (1.63–1.84)	1.24 (1.17–1.31)
Cardiac arrest (nonoperative or intraoperative)	395	73.9 (69.1–78.8)	73.9 (69.0–78.8)	0.92 (0.88–0.96)	0.82 (0.79–0.85)
Elective surgery (excluding cardiac surgery)	3,012	78.6 (74.8–82.4)	80.8 (77.3–84.4)	1.04 (1.00–1.09)	0.79 (0.76–0.83)
Aboriginal patients	863	77.8 (74.2–81.4)	78.8 (75.2–82.3)	1.02 (0.95–1.09)	0.82 (0.77–0.87)
Patients transferred from another hospital	1,127	79.4 (76.3–82.4)	80.4 (77.4–83.5)	0.87 (0.82–0.92)	0.71 (0.67–0.75)
Patients admitted between 1993 and early 1999	5,553	85.4 (84.0–86.7)	86.1 (84.8–87.4)	1.05 (1.01–1.09)	0.85 (0.82–0.88)
Patients admitted between early 1999 and 2003	5,554	83.3 (82.0–84.5)	84.1 (82.8–85.3)	1.09 (1.06–1.13)	0.88 (0.86–0.91)
Patients stayed in the ICU longer than 24 hours	8,461	80.4 (79.2–81.5)	81.2 (80.1–82.3)	0.99 (0.97–1.02)	0.79 (0.77–0.81)
Patients survived longer than 24 hours of hospitalisation	10,733	82.2 (81.1–83.2)	83.0 (82.0–84.0)	0.93 (0.91–0.95)	0.74 (0.73–0.76)

^aThere was no significant difference in the areas under the receiver operating characteristic (ROC) curves between the admission APACHE II model and the worst 24-hour APACHE II model (P = 1.00).