Shock index-based risk indices as prognostic predictor for in-hospital mortality in patients with ST-elevation myocardial infarction, the results from Henan STEMI registry

Abstract Background: Shock index-based risk indices predicting in-hospital mortality for ST-elevation myocardial infarction (STEMI) patients have been recently described, debate continues about their accuracy, especially compared with classic scoring system. Thus, we aim to evaluate the predictive value of shock index-based risk indices in STEMI patients and compared with thrombolysis in myocardial infarction (TIMI) risk score.Method: Consecutive 5063 STEMI patients were divided into 2 groups: non-survivor (392, 7.7%) and survivor (4671, 92.3%). Predictive performance of shock index-based risk indices and TIMI risk score were assessed by C-statistic, Hosmer-Lemeshow test, Nagelkerke-R2, brier scores, integrated discrimination improvement(IDI) and net reclassification improvement(NRI). Odd ratios (OR) and corresponding 95% confidence intervals of bipartite shock index-based risk indices were estimate by generalized linear mixed model.Results: The area under the curves (AUC) of shock index-based risk indices were smaller, whereas the sensitivity and specificity of age shock index (age SI) (0.73, 0.69) and age modified shock index (age MSI) (0.70, 0.73) were comparable to TIMI risk score (0.73, 0.77). The Hosmer-Lemeshow P values and the Nagelkerke-R2 of shock index-based risk indices were lower, whereas the brier scores were comparable with TIMI risk score. In-hospital mortality was increasing with the SI based risk indices, when the cut-off value were set, in-hospital mortality in the patients with larger shock index-based risk indices were relatively higher. The prognostic performance of shock index (SI, C-statistic: z=7.944, P<0.001; NRI: 0.749; IDI: 0.067), modified shock index(MSI, C-statistic: z=8.088, P<0.001; NRI: 0.774; IDI: 0.067), age SI(C-statistic: z=3.361, P<0.001; NRI: 0.534; IDI: 0.025), and age MSI(C-statistic: z=3.578, P<0.001; NRI: 0.680; IDI: 0.040) were inferior to TIMI risk score. Univariate and multivariate analysis showed that elevated shock index-based risk indices were associated with a higher rate of in-hospital mortality. Conclusions: Shock index-based risk indices do not have a significant advantage over TIMI risk score. Age SI and age MSI, with comparable sensitivity, were valuable prognostic tools to identify STEMI patients at high risk of in-hospital death.Trial registration: [NCT02641262] [29 December, 2015].