This was a single-center, open-label, RCT. This study was approved by the Institutional Review Board (IRB) of the Catholic University of Korea and performed in accordance with the guidelines and regulations of the IRB. Informed consent was obtained from all the included patients. The study was conducted after registration with Korea Clinical Research Information Service (KCT0004154).

Nonpregnant adult patients aged 19–70 years who were diagnosed with acute appendicitis without perforation on preoperative abdominal computed tomography (CT) were eligible. Consecutive patients who underwent surgery between August 6, 2019, and December 26, 2022, in Uijeongbu St. Mary’s Hospital were included, and the follow-up date of the last patient was January 04, 2023. The exclusion criteria were as follows: (1) history of abdominal surgery; (2) open conversion; (3) surgery other than laparoscopic appendectomy; (4) suspicion of perforation or periappendiceal abscess in the surgical field; (5) difficulty in applying a polymeric clip owing to a thick appendiceal base or severe inflammation; and (6) the final biopsy result not being appendicitis.

The sample size calculation was based on the results of a previous study that compared the use of polymeric clips with that of endoloops [12]. In this study, the operative time using polymeric clips and endoloops was 59 min and 68 min, respectively. Therefore, considering that a clinically meaningful difference in the average surgical time between using polymeric clips and endoloops is 9 min, the standard deviation calculated through the range of surgical time was confirmed to be 22.5 min. A sample size of 98 in each group achieved 80% power to reject the null hypothesis of equal means when the population mean difference was 9 min with a standard deviation for both groups of 22.5 min and a significance level (alpha) of 0.050 using a two-sided two-sample equal-variance t-test. Considering a dropout rate of 5%, 208 patients (104 patients per group) were included in this study.

Using SAS ver 9.4 (SAS Institute Inc., NC, Cary, USA) for Microsoft Windows, random assignment numbers were generated, and a random assignment envelope was created. Before a polymeric clip or an endoloop was applied, the envelope was opened, and the patients were assigned to either the intervention (polymeric clip) or the control (endoloop) group. This was a single-blinded study where the use of polymeric clips or endoloops was not blinded to the investigators, including outcome accessors, but to the patients.

The primary endpoint was the difference in surgical time between the polymeric clip and endoloop groups. The secondary endpoints were differences in the time from the introduction of each instrument to appendiceal base cutting, operation and anesthesia fees, as well as the frequency of complications.

The amount of time from the initiation of skin incision to the completion of skin suturing was defined as the total surgical time. To minimize bias in surgical timepoints, the surgical time was subdivided into skin incision, mesoappendiceal dissection (from start to completion time), polymeric clip or endoloop application (from start to appendix cutting time), and skin suture completion time.

In both groups, surgery was performed through three abdominal incisions (one with a 12-mm trocar and two with 5-mm trocars) and using a 5-mm scope. The mesoappendix was dissected using an energy and/or monopolar device. When ligating the appendiceal base, two polymeric clips (Gems-clip Plus, size: XL [12 mm]) and one endoloop (Gemsloop-PGLA) were used in the intervention and control groups, respectively. After the appendix was cut, a drainage tube was placed according to the surgeon's judgment. The specimen was extracted using a plastic bag via the 12-mm trocar site and the trocar was then removed, followed by suturing the skin. The operation and anesthesia fees for each surgery were then calculated.

Postoperative acute complications were monitored during hospitalization. If the patients agreed and there were no specific complications, they were discharged on the second postoperative day.

One to two weeks after surgery, the patients were checked for postoperative complications during an outpatient visit.

Continuous variables are presented as mean and standard deviation in cases of normal distribution, as well as median and interquartile range (IQR) values in cases of non-normal distribution. Categorical variables are presented as frequencies and percentages. To evaluate the difference between the two groups in continuous variables, the normality test was performed followed by the independent T-test or Wilcoxon's rank sum test. For categorical data, a chi-square test or Fisher's exact test was performed. All statistical analyses were performed using SPSS version 21.0 for Windows (IBM Corp, Armonk, NY, USA), and the significance level was set to 0.05.