Statistical analysis
Continuous data are presented as mean ± standard deviation or median
[range], and categorical variables are given as counts and
percentages. Survival rates were calculated using the Kaplan–Meier
method. Statistical analyses were performed using the Stat-View
Statistical Software Package 5.0 (SAS Institute, Inc., Cary, NC, USA),
NCSS 2001 (Number Cruncher Statistical System, Kaysville, Utah).