Statistical Analysis
Continuous data are expressed as the median (25–75 interquatile range), although the Barthel index is expressed as mean ± SD. All continuous data were compared between the two groups using Mann–Whitney U test. Categorical data are expressed as frequencies (%) and evaluated using the chi-square test or Fisher’s exact test. The prognostic value of the duration that patients could walk 100 m or 200 m after surgery was evaluated using receiver operating characteristic (ROC) curve for late mortality. Overall survival was defined as the time from surgery to death from any cause. Time-related survival was estimated using Kaplan–Meier method and compared using a log-rank test between the two groups. Cox proportional hazards analysis was used to determine the risk factors for late mortality. Predictors were entered into a univariable analysis, and any variable with a p value of ≤0.05 (and aged ≥70 years) was entered into the multivariable analysis. All statistical analyses were performed using EZR (Saitama Medical Center, Jichi Medical University, Saitama, Japan) or Prism version 8.0 (GraphPad Software, San Diego, CA, USA). A p value of <0.05 was considered statistically significant. The overall survival and ROC curve figures were created using Prism version 8.