Background and purpose: Acute Physiology and Chronic Health Evaluation (APACHE II) is a scoring system that describes and predicts the severity of acute illness in patients admitted in intensive care units. Its application is helpful in therapeutic monitoring methods, comparing the effectiveness of treatments and the decision to change the treatment, and comparing the performance and quality of services provided. The aim of this study was to compare the probable mortality rate predicted by APACHE II and the actual mortality rate.

Materials and methods: A prospective cohort study was performed in …….. The patients (over 16 years old) were selected from Emergency Department in Sari Imam Khomeini Hospital with indications for admissions to intensive care unit. The predicted risk of death was calculated for each patient using the APACHE II and compared with the actual rate of death.

Results: In this study, 82 patients enrolled including 54 males (65.9%) and 28 females (34.1%). The APACHE II average score was 19.69± 8.91 and the percentage of mortality rate was 38.43±27.62 while the actual mortality rate was 48%. The accuracy of APACHE II scale in predicting the mortality rate was 63.4%.

Conclusion: The APACHE II scoring system can provide an acceptable estimate of mortality. In calibration of the system it was found with the discontinuity especially in the range of 0.01 to 0.1 and 0.5 to 0.7 scores.