Comparison between SAPS II and SAPS 3 in predicting hospital mortality in a cohort of 103 Italian ICUs. Is new always better?

Servizio Anestesia e Rianimazione, Ospedale Civile San Martino, Belluno, Italy.
European Journal of Intensive Care Medicine (Impact Factor: 5.17). 05/2012; 38(8):1280-8. DOI: 10.1007/s00134-012-2578-0
Source: PubMed

ABSTRACT More recent severity scores should be more reliable than older ones because they account for the improvement in medical care over time. To provide more insight into this issue, we compared the predictive ability of the Simplified Acute Physiology Score (SAPS) II and SAPS 3 (originally developed from data collected in 1991-1992 and 2002, respectively) on a sample of critically ill patients.
This was a prospective observational study on 3,661 patients from 103 Italian intensive care units. Standardized mortality ratios (SMRs) were calculated. Assessment of calibration across risk classes was performed using the GiViTI calibration belt. Discrimination was evaluated by means of the area under the receiver operating characteristic analysis.
Both scores were shown to discriminate fairly. SAPS 3 largely overpredicted mortality, more than SAPS II (SMR 0.63, 95 % CI 0.60-0.66 vs. 0.87, 95 % CI 0.83-0.91). This result was consistent and statistically significant across all risk classes for SAPS 3. SAPS II did not show relevant deviations from ideal calibration in the first two deciles of risk, whereas in higher-risk classes it overpredicted mortality.
Both scores provided unreliable predictions, but unexpectedly the newer SAPS 3 turned out to overpredict mortality more than the older SAPS II.

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    European Journal of Intensive Care Medicine 05/2012; 38(8):1246-8. · 5.17 Impact Factor
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    ABSTRACT: Objectives. Cardiac surgery patients are excluded from SAPS2 but included in SAPS3. Neither score is evaluated for this exclusive population; however, they are used daily. We hypothesized that SAPS3 may be superior to SAPS2 in outcome prediction in cardiac surgery patients. Design. All consecutive patients undergoing cardiac surgery between January 2007 and December 2010 were included in our prospective study. Both models were tested with calibration and discrimination statistics. We compared the AUC of the ROC curves by DeLong's method and calculated OCC values. Results. A total of 5207 patients with mean age of 67.2 ± 10.9 years were admitted to the ICU. The mean length of ICU stay was 4.6 ± 7.0 days and the ICU mortality was 5.9%. The two tested models had acceptable discriminatory power (AUC: SAPS2: 0.777-0.875; SAPS3: 0.757-893). SAPS3 had a low AUC and poor calibration on admission day. SAPS2 had poor calibration on Days 1-6 and 8. Conclusions. Despite including cardiac surgery patients, SAPS3 was not superior to SAPS2 in our analysis. In this large cohort of ICU cardiac surgery patients, performance of both SAPS models was generally poor. In this subset of patients, neither scoring system is recommended.
    Scandinavian cardiovascular journal: SCJ 03/2014; · 1.07 Impact Factor
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    ABSTRACT: Background Mortality prediction is important in intensive care. The Simplified Acute Physiology Score (SAPS) II is a tool for predicting such mortality. However, the original SAPS II is poorly calibrated to current intensive care unit (ICU) populations because it draws on data, which is more than 20 years old. We aimed to improve the calibration of SAPS II using data from the Norwegian Intensive Care Registry (NIR). This is the first recalibration of SAPS II for Nordic data.MethodsA first-level customization was applied to improve calibration of the original SAPS II model (Model A). NIR data used covered more than 90% of adult patients admitted to ICUs in Norway from 2008 to 2010 (n = 30712).ResultsThe modified SAPS II, Model B, outperformed the original Model A with respect to calibration. Model B gave more accurate predictions of mortality than Model A (Hosmer–Lemeshow's C: 22.01 vs. 689.07; Brier score: 0.120 vs. 0.131; Cox's calibration regression: α = −0.093 vs. −0.747, β = 0.921 vs. 0.735, (α|β = 1) = −0.009 vs. −0.630). The standardized mortality ratio was 0.73 [95% confidence interval (CI) of 0.70–0.76] for Model A and 0.99 (95% CI of 0.95–1.04) for Model B. Discrimination was good for both models (area under receiver operating characteristic curve = 0.83 for both models).Conclusions As expected, Model B is better calibrated than Model A, and both models have similar uniformity of fit and equal discrimination. Introducing Model B into Norwegian ICUs may improve precision in decision-making. Units will have a more realistic benchmark for the assessment of ICU performance. Mortality risk estimates from Model B are better than previous SAPS II estimates have been.
    Acta Anaesthesiologica Scandinavica 06/2014; · 2.36 Impact Factor


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May 15, 2014