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Performance of the APACHE IV system in patients with acute renal failure


Scoring systems represent classification systems or point systems that have been designed for making quantitative statements regarding the severity of a disease, its course and its prognosis [1]. These systems are based on physiologic abnormalities and have been successful in measuring severity of illness among critically ill patients [2]. The APACHE IV system has already been validated in our population at King Faisal Specialist Hospital and Research Center [3], and the purpose of this study is to evaluate the performance of this system in a subset of patients with acute renal failure.


Fifty-four consecutive patients with acute renal failure defined as a creatinine value ≥ 1.5 mg/dl and urine output <410 ml/24 hours were admitted to a medical/surgical ICU between January 2007 and March 2008 and were enrolled in the study. The length of stay and mortality percentages were predicted using APACHE IV, and both variables were compared with the observed data. The Wilcoxon rank sum test is used to calculate statistical significance for continuous data and the chi-square test for categorical data.


A total of 54 patients with mean age of 53.8 years were included. Fifty-six percent were males; 62% of patients were medical, 38% were surgical. The predicted ICU length of stay of 6.3 days (SD = 2, range of 2.1 to 10.2) was insignificantly lower than the observed ICU length of stay of 8.0 days (SD = 8.5, range of 1 to 45) (P < 0.12: Wilcoxon test for nonparametric) (Figure 1). The observed mortality of 44.4% was not statistically different from predicted mortality of 42.1 (χ2 = 0.07, P = 0.8) (Figure 2). The standardized mortality ratio is 1.06 (P = 0.79, 95% CI = 0.7 to 1.5).

Figure 1
figure 1

Observed and predicted length of stay (LOS).

Figure 2
figure 2

Observed and predicted mortality among patients.


The APACHE IV predicted mortality and length of stay equations perform well in a subset of patients with acute renal failure in our population.


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Dahhan, T., Al-Sanouri, I., Al-Awadhi, H. et al. Performance of the APACHE IV system in patients with acute renal failure. Crit Care 13 (Suppl 1), P509 (2009).

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  • Creatinine
  • Scoring System
  • Acute Renal Failure
  • Categorical Data
  • Continuous Data