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.