Data collection
Data from our institution were preferentially considered compared to
those from other institutions in order to eliminate selection bias in
data from different hospitals. If patients who had been transferred were
unable to undergo examination at our institution owing to their critical
condition, data collected at other institutions were used. Perioperative
data of all patients, including general characteristics, disease
history, comorbidities, physical examination findings, laboratory test
results, imaging data, and outcomes, were collected, entered by
specialists, and reviewed by experienced and senior doctors.