APACHE IV: benchmarking in an Indian ICU

Introduction

APACHE II has been used worldwide for measuring ICU performance. The patient cohort from which APACHE II was derived was calibrated and validated two decades ago. Due to substantial advancement in critical care, a new cohort was studied recently and APACHE IV was derived for benchmarking ICU performance. The objective of the study is to compare APACHE II with APACHE IV outcome prediction in the same cohort of critically ill population.

Methods

The study was carried out in a 40-bed mixed medical–surgical, adult, semiclosed ICU at a tertiary-care centre. All consecutive patients from January 2007 to October 2008 were studied. Patient demography was recorded. APACHE II and APACHE IV scores were calculated on each patient and statistical comparison was performed.

Results

During the study period the total ICU admission was 3,647 patients. Patients with limitation of life support and discharge against medical advice were excluded. Cases where data were incomplete were also excluded, and 2,919 patients were finally analyzed. The median APACHE II and APACHE IV scores of the study cohort were 12 (8 to 18) and 44 (30 to 62). The median predicted mortality over the study period was significantly higher with APACHE II scoring in comparison with APACHE IV (15 (8 to 25) vs. 4.6 (1.66 to 12.67)) (P = 0.00001). The standardized mortality ratio was likewise significantly lower with APACHE II in comparison with APACHE IV (median = -0.87 vs. 2.85, mean = -1.13 vs. 8.18) (Figure 1) (P = 0.00001).

Figure 1

A2 SMR, APACHE II standardized mortality rate; A4 SMR, APACHE IV standardized mortality rate.

Conclusion

Currently, APACHE II benchmarking overestimates ICU performance and APACHE IV might be more relevant tool to estimate ICU performance.