Predicting survival, length of stay, and cost in the surgical intensive care unit: APACHE II versus ICISS.
ABSTRACT Risk stratification of patients in the intensive care unit (ICU) is an important tool because it permits comparison of patient populations for research and quality control. Unfortunately, currently available scoring systems were developed primarily in medical ICUs and have only mediocre performance in surgical ICUs. Moreover, they are very expensive to purchase and use. We conceived a simple risk-stratification tool for the surgical ICU that uses readily available International Classification of Diseases, Ninth Revision, codes to predict outcome. Called ICISS (International Classification of Disease Illness Severity Score), our score is the product of the survival risk ratios (obtained from an independent data set) for all International Classification of Diseases, Ninth Revision, diagnosis codes.
A total of 5,322 noncardiac patients admitted to a surgical ICU during an 8-year period had their Acute Physiology and Chronic Health Evaluation (APACHE) II scores compared with their ICISS as predictors of outcome (survival/nonsurvival, length of stay, and charges).
ICISS proved to be a much better predictor of survival than APACHE (receiver operating characteristic (ROC) APACHE = 0.806; Hosmer-Lemeshow (HL) APACHE = 22.56; ROC ICISS = 0.892; HL ICISS = 12.06) or the APACHE survival probability (ROC = 0.836; HL = 34.47). These differences were highly statistically significant (p < 0.001). ICISS was also better correlated with ICU length of stay (APACHE R2 = 0.06; ICISS R2 = 0.32) and ICU charges (APACHE R2 = 0.07; ICISS R2 = 0.39). When combined in a logistic model with ICISS, APACHE II added slightly to the predictive power of ICISS alone (combined ROC = 0.903) but degraded the calibration of the model (combined HL = 16.29; p = 0.038).
Because ICISS is both more accurate and much less expensive to calculate than APACHE II score, ICISS should replace APACHE II score as the standard risk stratification tool in surgical ICUs.
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ABSTRACT: Introduction The clinical-financial management of an intensive care unit (ICU) necessitates a method to approximate individual costs and establish a costs proxy. The aim of this study was to analyze actual costs and their estimation through severity and activity scores, as well as to evaluate whether at an individual level the nine equivalents of nursing manpower use score (NEMS) could be useful for their measurement. Method We performed a cohort study of patients admitted to an ICU in 2000. Stratified random sampling was used to select 106 patients with the 14 most common diagnosis-related groups (DRG). Direct variable costs for each patient were registered with allocation of direct and indirect fixed costs according to length of hospital stay. Length of hospital stay, physiological severity of illness indices (APACHE II, SAPS II, MPM 0, MPM 24) and therapeutic dependence scales (NEMS, TISS-28 and OMEGA) were measured. Statistical analysis was based on Spearman’s correlation coefficient between total costs and indexes. The actual and theoretical costs calculated on the basis of the NEMS were compared by the median difference between these costs (AMD, 5th and 95th percentile) and by the Bland and Altman analysis. The values are expressed as means (95% confidence interval). Results One hundred and six patients were selected from 861 patients in whom length of hospital stay was 1 day or more. The mean age was 68.2 years (65.4; 71.0); 74 were men; length of hospital stay: 7.3 (5.3; 9.3); mean APACHE II score: 17.6 (16.0; 19.2); NEMS: 219.7 (153.7; 285.8); DRG weight: 5.8 (4.6; 6.9); cost/patient 6767.34 euros (4919.95; 8614.74); costs per DRG/patient: 6282.29 euros (4992.82; 7571.76); cost/NEMS: 12.42 euros (11.09; 13.76); cost/length of hospital stay ratio: 921.28 euros (888.22; 954.34). The results of Spearman’s correlation coefficient were as follows, r (p): Length of hospital stay: 0.98 (0.000); APACHE II 0.36 (0.000); SAPS II 0.27 (0.007); MPM 0 0.20 (0.032); MPM 24 0.21 (0.029); NEMS 0.92 (0.000); TISS-28 0.91 (0.000); OMEGA 0.85 (0.000); DRG weight 0.55 (0.000). AMD: –154.71 (–3719.86/958.07). Conclusions Cost calculation through the method described was more approximate than allocation by DRG. The component with the greatest impact on total costs was length of hospital stay. NEMS may be useful for calculating actual costs. Even when there are individual differences between actual and estimated costs, the method used can be useful to calculate the financial resources of an ICU.Medicina Intensiva 01/2003; 27(7):453–462. · 1.24 Impact Factor
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ABSTRACT: Trauma and Injury Severity Score (TRISS) has been the benchmark of mortality risk in trauma centers for over 30 years. TRISS utilizes the Injury Severity Score (ISS) as an index of anatomical injury. This study investigated the efficacy of a new type of index of anatomical injury called the ICD-derived Injury Severity Score (ICISS) compared to the ISS using a logistic regression analysis and a global chi-square test of the areas under the Receiver Operator Characteristic (ROC) curves. We found that the empirically derived ICISS performed as well as the consensus derived ISS with no statistical differences between their respective area under the ROC curves.McGill journal of medicine: MJM: an international forum for the advancement of medical sciences by students 01/2008; 11(1):9-13.
- Anesthesiology 10/2013; 119(4):959-81. · 6.17 Impact Factor