predictive capability of apache ii score in determining mortality among critically ill surgical population

ABSTRACT

The APACHE II model has been widely validated and used by many ICUs to classify the severity of illness and to predict hospital mortality, Although the APACHE II model is quite old, and other scoring systems have been developed using more recent cohorts, APACHE II is still widely used for research and clinical audit purposes. It scored the most accurate mortality prediction. Because of the differences between intensive care unit patients, in criteria of admission and type of surgery, we think it is necessary for every intensive care unit to have a prediction system which is validated for its specific kind of patients. This prospective study was done on 680 consecutive patients admitted to surgical intensive care unit [SICU] of Kasr EI-Aini hospital were enrolled from January 2006 to December 2007. For standardization purpose, 54 patients, who remained less than 24 hours, were excluded. Another 75 patients were excluded as their medical files could not provide all required information. The APACHE II score was calculated for the remaining 551 patients, physiological variables, age and chronic disease. The SICU resident filled the APACHE II form which is a routine form of SICU. The least value was used for calculating the physiological variable during the first 24 hours of admission. Patients were classified according to surgical procedure formed, into post-elective and post-emergency, an equation established by Knaus et al. in 1985 was used for the calculation of mortality risk. From the 551 patient enrolled the mean age was 46.93 +/- 17.9 years and the length of SICU stay was 3.77 +/- 3.9 days. The overall median APACHE II score of all SICU patients was 8 with a range of 51 [minimum 0 and maximum 51]. The expected mortality rate was 15.95 +/- 22.0%. The actual mortality rate was 92 patients [16.7%]. There was significant difference among distribution of male female, survivors non-survivors and elective emergency patients enrolled [p=0.03, <0.0001 and <0.0001 respectively] APACHE II score had a strong positive correlation with actual mortality rate. There was good correlation between predicted death risk and actual mortality rate r=0.75 and p<0.0001. We conclude that this study demonstrated a meaningful association between predicted and observed mortality rates in patients in SICU in a tertiary referral university hospital [Kasr EI-Aini hospital] relying on APACHE II score evaluation. APACHE II prognostic index was useful for stratifying patients according to the severity of their health condition