External validation of simplified out-of-hospital cardiac arrest and cardiac arrest hospital prognosis scores in a Japanese population: A multicentre retrospective cohort study
Abstract Background Out-of-hospital cardiac arrest (OHCA) is a global medical problem. The newly-developed simplified out-of-hospital cardiac arrest (sOHCA) and cardiac arrest hospital prognosis (sCAHP) scores used for prognostication of patients admitted alive have not been validated externally. This study was, thus, conducted to externally validate sOHCA and sCAHP scores in a Japanese population. Methods Adult patients resuscitated and admitted to hospitals after intrinsic OHCA (n=2,428, age ≥18 years) were selected from a prospectively collected Japanese database (January 2012–March 2013). We validated sOHCA and sCAHP scores with reference to the original ones in predicting 1-month unfavourable neurological outcomes based on discrimination and calibration measures. Discrimination and calibration were assessed using area under the receiver operating characteristic curve (AUC) and the Hosmer-Lemeshow goodness-of-fit test with calibration plot, respectively. Results One-month unfavourable neurological outcome was observed in 82% of patients. Score availability was significantly higher in the simplified scores than in the original ones and was highest in the sCAHP score (76%). The AUCs of simplified scores were not significantly different from those of original ones, whereas the AUC of the sCAHP score was significantly higher than that of the sOHCA score (0.88 vs. 0.81, P <0.001). Goodness-of-fit was poor in the sOHCA score (ν= 8, χ 2 =19.1, Hosmer-Lemeshow test: P =0.014) but not in the sCAHP score (ν= 8, χ 2 =13.5, Hosmer-Lemeshow test: P =0.10). Conclusion Performance of original and simplified OHCA and CAHP scores in predicting neurological outcomes in successfully resuscitated OHCA patients were acceptable. Based on the highest availability, similar discrimination, and good calibration, the sCAHP score was the better candidate for clinical implementation. The validated predictive score can help patients’ families, healthcare providers, and researchers by accurately stratifying patients.