Predictive Performance of the Simplified Acute Physiology Score (SAPS) II and the Initial Sequential Organ Failure Assessment (SOFA) Score in Acutely Ill Intensive Care Patients: Post-Hoc Analyses of the SUP-ICU Inception Cohort Study

Abstract

PurposeSeverity scores including the Simplified Acute Physiology Score (SAPS) II and the Sequential Organ Failure Assessment (SOFA) score are used in intensive care units (ICUs) to assess disease severity, predict mortality and in research. We aimed to assess the predictive performance of SAPS II and the initial SOFA score for in-hospital and 90-day mortality in a contemporary international cohort.MethodsThis was a post-hoc study of the Stress Ulcer Prophylaxis in the Intensive Care Unit (SUP-ICU) inception cohort study, which included acutely ill adults from ICUs across 11 countries (n = 1034). We compared the discrimination of SAPS II and initial SOFA scores, compared the discrimination of SAPS II in our cohort with the original cohort, assessed the calibration of SAPS II customised to our cohort, and compared the discrimination for 90-day mortality vs. in-hospital mortality for both scores. Discrimination was evaluated using areas under the receiver operating characteristics curves (AUROC). Calibration was evaluated using Hosmer-Lemeshow’s goodness-of-fit Ĉ-statistic.ResultsAUROC for in-hospital mortality was 0.80 (95% confidence interval (CI) 0.77–0.83) for SAPS II and 0.73 (95% CI 0.69–0.76) for initial SOFA score (P<0.001 for the comparison). Calibration of the customised SAPS II for predicting in-hospital mortality was adequate (P = 0.60). Discrimination of SAPS II was reduced compared with the original SAPS II validation sample (AUROC 0.80 vs. 0.86; P = 0.001). AUROC for 90-day mortality was 0.79 (95% CI 0.76–0.82; P = 0.74 for comparison with in-hospital mortality) for SAPS II and 0.71 (95% CI 0.68–0.75; P = 0.66 for comparison with in-hospital mortality) for the initial SOFA score.ConclusionsThe predictive performance of SAPS II was similar for in-hospital and 90-day mortality and superior to that of the initial SOFA score, but SAPS II’s performance has decreased over time. Use of a contemporary severity score with improved predictive performance may be of value.

Development and internal validation of the Simplified Mortality Score for the Intensive Care Unit (SMS‐ICU)

“…Whether the lower performance of our score compared with more complex scores is due to the chosen outcome measure, simplicity of the model or a combination is not possible to assess from our data. However, in a recent study from our group, we found little difference in SAPS II's discrimination for in‐hospital vs. 90‐day mortality . Third, mortality prediction scores have been criticised for predicting the obvious; e.g.…”

“…Existing severity scores are time‐consuming and complex to use, and their interpretation is often hampered by missing data . Performance of SAPS II is similar to that of the more complex SAPS 3, and the Sequential Organ Failure Assessment (SOFA) score appears to be similar or only slightly inferior at discriminating between survivors and non‐survivors compared with SAPS II, despite being simpler and not developed for this purpose. Finally, severity score performance is affected by the choice of outcome .…”

Validation of APACHE II and SAPS II scales at the intensive care unit along with assessment of SOFA scale at the admission as an isolated risk of death predictor

“…In the above mentioned and some other studies comparing the usefulness of scales, the values for SOFA ranged from 0.67 to 0.84 [6][7][8][10][11][12][13].…”

Comorbidities impact on the prognosis of severe acute community-acquired pneumonia

“…Also, the SOFA score was not designed for mortality prediction but to evaluate organ dysfunction and morbidity. 33 On the other hand, the fact that just the APACHE II and the PSI system scores showed statistical differences highlights the hypothesis that mortality prediction may be related to prior health conditions. Apart from these two score systems, only the SAPS II takes prior health conditions into consideration and, although its results were not statistically significant, it was the third more accurate system predicting mortality.…”