During the study period, there were 59,643 admissions with ward vital signs, including 109 ward cardiac arrests, 291 deaths within 24 h of a ward vital sign, and 2,655 ward-to-ICU transfers. The included patients had a mean age of 55 ± 18 years; 56% were women, 43% were black, 36% were white, and 34% underwent surgery during the hospitalization. Results from the early warning score comparisons are shown in Table 5, separated by outcome. We found a wide range of accuracy, both across outcomes for a given system and across systems. In general, mortality resulted in the highest AUCs, whereas ICU transfer resulted in the lowest. Overall, the aggregate weighted scoring systems outperformed the other systems for most outcomes, with the SEWS, MEWS, ViEWS, and CART score being the most accurate. In addition, the modified MERIT criteria described by Cretikos and colleagues23 were more accurate than the original MERIT criteria for all outcomes. Although the ViEWS, CART, MEWS, and SEWS were similar in performance across the outcomes, the CART score had the highest AUC for cardiac arrest (0.83), ICU transfer (0.77), and the composite outcome (0.78), whereas the CART score, ViEWS, and SEWS all had the same AUC for mortality (0.88). The ViEWS was the second most accurate system for detecting cardiac arrest (0.77), and the SEWS was the second most accurate for ICU transfer (AUC 0.75) and the composite outcome (AUC, 0.76). Since the CART score was derived using many of the patients from this dataset, we repeated the analysis for the CART score using only those patients not in the original study (ie, prospective validation) and found similar results (AUCs of 0.86, 0.76, 0.87, and 0.77 for cardiac arrest, ICU transfer, mortality, and the composite outcome, respectively). Sensitivity and specificity values at cut-points closest to 85%, 90%, and 95% specificity for the four most accurate systems for detecting cardiac arrest are shown in Table 6. At a specificity threshold of approximately 90%, the CART score had a sensitivity of 49%, compared with the ViEWS (41%), MEWS (39%), and the centile-based system (35%, data not shown). The SEWS and the multiple-parameter system by Bleyer and colleagues24 did not have cut-offs near this level of specificity. The MERIT criteria had a sensitivity and specificity of 45% and 82% for detecting cardiac arrest compared with the modified criteria proposed by Cretikos et al,23 which had a sensitivity of 54% and specificity of 84%.