Statistical analysis
Intergroup comparisons of continuous variables were performed using Student’s t-test or the Mann–Whitney U test. Comparisons of nominal variables were performed using the chi-square test or Fisher’s exact test. A receiver operating characteristic (ROC) curve was constructed using GNRI, serum albumin level, BMI, and A-DROP score as the test variables and in-hospital mortality events as the state variables. The area under the ROC curves (AUCs) was used to compare the predictive value of GNRI, albumin level, BMI, and A-DROP score. Logistic regression analysis was performed to identify significant variables for in-hospital mortality. Statistically significant variables were used in the univariate model, and clinically relevant variables were further analyzed using multivariate analysis. All statistical analyses were performed using EZR (Saitama Medical Center, Jichi Medical University, Saitama, Japan), a graphical user interface for R (The R Foundation for Statistical Computing, Vienna, Austria).19 Statistical significance was set at p < 0.05.