Statistical Analysis
Continuous variables were reported as mean values (standard deviation) or median [interquartile range] and were compared using the Student’s t test or Wilcoxon’s rank-sum test as appropriate. Categorical variables were expressed as number (percentage) and were compared using Fisher’s exact test. Survival analysis was performed using a Kaplan-Meier estimator and estimates of survival were compared using the log-rank test. Statistical analyses were conducted using R version 3.0.2 (R Foundation, Vienna, Austria) and the survival package.