Dr. Goldhill et Ps. Withington, MORTALITY PREDICTED BY APACHE-II - THE EFFECT OF CHANGES IN PHYSIOLOGICAL VALUES AND POST-ICU HOSPITAL MORTALITY, Anaesthesia, 51(8), 1996, pp. 719-723
The contribution of physiological values to the APACHE II score was de
ter mined by retrospective analysis of 11 348 patients undergoing inte
nsive care. Eleven physiological variables contributed a mean of 8.9 p
oints, 54% of the total APACHE II score. The mortality ratio (observed
hospital mortality/hospital morality predicted by APACHE II) was 1.13
. We altered the APACHE II scores and post-intensive care hospital mor
tality in order to examine the effect on the mortality ratio of these
changes. Increasing scores by two or four points decreased mortality r
atios to 1.00 and 0.89 respectively: decreasing scores by two or four
points to a minimum of zero increased mortality ratios to 1.27 and 1.4
4 respectively. A 25% increase or decrease in post-intensive care hosp
ital mortality changed mortality ratios to 1.21 and 1.05 respectively.
Physiological values vary with the timing of collection and accuracy
of recording. Small consistent differences in scores cause potentially
important changes in the mortality ratio. Unless data collection and
the effect of management before and after intensive care are standardi
sed, using mortality ratios to compare intensive care units is likely
to be inaccurate and misleading.