Randomization and data management
CRF
CRF, SILS
The sample size was determined by the early morbidity. According to the non-inferiority design, this analysis was based on an alpha of 0.025, a power of 80%, and a margin delta of 20%; a sample of at least 90 participants per group was calculated using the NCSS-PASS (11th edition, NCSS, LLC, Utah, USA). Assuming a 10% drop-out rate, the total number of participants needed per group was 99. Patients were randomized to undergo SILS + 1 or CLS according to a computer-generated randomization list at a 1:1 ratio. A research coordinator gave the surgeon the patients’ randomization numbers and group assignment in identical, opaque, sealed envelopes the day before surgery. All data were recorded in the case report form (CRF) by a research coordinator and reviewed by another coordinator. The CRF were double-checked to ensure the accuracy of the data before it was transferred into the trial database. An investigator reviewed the database to ensure accurate data collection using descriptive statistics to check for missing data and out-of range values. Any unclear data will be traced to the original medical records.