Study objectives: To evaluate the acute physiology,
age, chronic health evaluation III (APACHE III) scoring system in the
context of general adult ICUs in the United Kingdom.
Design: Prospective, noninterventional, cohort study.
Setting: Seventeen general adult ICUs in a discrete area of
Patients: 12,793 patients admitted
between April 1, 1993 and December 31, 1995.
Measurements: Sociodemographic and severity-of-illness data
were collected for all patients admitted to the study units. Formal
goodness-of-fit tests were applied and observed mortality was compared
with that predicted by using the APACHE III system.
Results: For the group of ICUs as a whole, the
risk-adjusted standardized mortality ratio (SMR) was 1.23 (95%
confidence intervals, 1.12–1.25). For 11 out of 17 ICUs, the SMR was
significantly greater than unity (p < 0.05). Calibration, as tested
by Hosmer-Lemeshow statistics, was poor (H2 = 312.54;
C2 = 332.85; df = 8; p < 0.01); however, model
discrimination was good with a total correct classification rate of
82.9% and an area under the receiver operating characteristic curve of
Conclusions: The excess mortality observed after
case-mix adjustment using the APACHE III system in this study may be
the result of either poor intensive care performance as compared with
the United States or a failure of the APACHE III equation to fit the UK
Abbreviations: A&E = accident and emergency;
APACHE = acute physiology, age, chronic health evaluation;
CI = confidence interval; ROC = receiver operating characteristic;
SMR = standardized mortality ratio; TCCR = total correct