2.4 Statistical analysis
Quantitative data are presented as Mean±SD, qualitative data as frequency number (%). Comparisons among the groups were performed by one-way ANOVA. If there was a difference, then S-N-K test was used. T‐test was used to compare between two groups. Chi-square test was used to compare binary variables. Since values of NT-pro BNP and hs-TnT were not normally distributed, data were log-transformed for multivariate analyses. Pearson’s correlation was used to test the association between LV GLS and log hs-TnT, as well as NT-pro BNP. The Receiver Operating Characteristic (ROC) curve was performed to evaluate the GLS’s and GCS’s ability to predict the severity of the disease. Area under the curve(AUC)<0.5 has no diagnostic value, 0.5<AUC<0.7 has low diagnostic value, 0.7<AUC<0.9 has medium diagnostic value, and AUC>0.9 has high diagnostic value.9 when AUC>0.9, according to Youden Index, combining sensitivity and specificity, find the best diagnostic cut point.P <0.05 was considered significant. All statistical tests were analyzed with SPSS (version 19.0) software.