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Single-incision Laparoscopic Appendectomy (SILA) Effects

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Title: Single-incision laparoscopic appendectomy versus conventional 3-port laparoscopic appendectomy for appendicitis patients: Ameta-analysisof randomized controlled trials


Purpose To analysis and discuss clinical effects of single-incision laparoscopic appendectomy (SILA) and conventional 3-port laparoscopic appendectomy (3-port LA) for appendicitis patients, we conducted a meta-analysis of randomized controlled trials (RCTs) through collecting published data.

Methods RCTs comparing the effects of SILA and 3-port LA were searched for in PubMed, Embase-Springer link-The Cochrane library. The differences of SILA and 3-port LA on operative time, length of hospital stay, total postoperative complications, and wound infection were discussed. Specially, Continues varies were pooled by weighted mean difference with 95% confidence interval. Classic varies were pooled by odds ratios with 95% confidence interval.

Results Eleven RCTs (731 patients for SILA, 725 patients for 3-port LA) met the inclusion criteria. There were significant differences in operative timeˆMD=8.53,95%-7.35-9.70 and analgesic used doseˆMD=0.96,95%-0.45-1.47‰between the SILA and 3-port LA. But the length of hospital stay, total postoperative complications, wound infection, intra-abdominal abscess, postoperative ileus and postoperative of 12/24 pain scores of SILA were similar to that of 3-port LA. There was no significantly publication bias among trials.

Conclusion Findings from this meta-analysis suggest that there was no significant difference in the clinical effects between the SILA and 3-port LA. SILA is safe and efficient but with no obvious advantages over 3-port LA.

Keywords Single-incision; Laparoscope; Appendicitis; Meta-analysis


Appendectomy is one of the most common operations done by general surgery1. Conventional 3-port laparoscopic appendectomy (3-port LA) has been widely acknowledged and recommended by a majority of surgeons and appendicitis patients. Compared with open appendectomy, 3-port LA has several advantages such as less surgical trauma, decreased postoperative wound infection and reduced postoperative pain and so on2, 3. Then, single-incision laparoscopic appendectomy (SILA) began to be introduced and applied for the laparoscopic appendectomy with the ongoing pursuit of reducing surgical trauma. However, some researchers indicated that SILA didn’t significantly improve postoperative recovering effects. SILA leads to a longer operative time and a higher postoperative pain scores, and the patients need more analgesics to feel comfortable4-7.

The meta-analysis was performed to assess clinical effects and the safety of SILA compared with 3-port LA. Although there have been a few prospective studies of differences between SILA and 3-port LA on the clinical results and security 7, 8, that is not enough and maybe some references have still not been undetected. Therefore, it is necessary to get newest data for assessing the benefits and disadvantages of SILA compared with 3-port LA.

Material and Methods

Search strategy

We searched PubMedŒEmbaseŒSpringer link, The Cochrane library from their inception to April 11th 2014. The main search terms were “single-incision” or” laparoscopic” or “appendectomy” or” appendectomies” with no any language restrictions. Moreover, the electronic search was supplemented by a hand search in print documents. We also searched the references of reviews and included studies to assure all relevant studies be checked for the meta- analysis.

Studies selection

Studies were included in the meta-analysis if they met the following criteria: (1) be RCTs; (2) study object is the appendicitis patients; (3) experimental group adopted SILA treatment; (4) Control group adopted 3-port LA treatment; (5) studies have reported the data on operative time, length of hospital stay(LOS)Πtotal postoperative complications(TPC), wound infection, intra-abdominal abscess(IAA), postoperative ileus, postoperative pain scores(PPS), analgesic use and so on.

Studies were excluded if they met the following criteria: (1) animal trials; (2) incomplete data or the data cannot be used for statistical analysis; (3) reviews, letters and comments; (4) if the data was repeatedly used in multiple published papers, we included the one with the most detailed information.

Data extraction

Two review authors independently extracted data from the full versions of the manuscripts. The extracted information included the name of the first author and publication year, geographic region of the research, the age and gender of the patients, sample size of experimental group and control group, register number of the research and so on. Exchange extracted table when the work was finished. Differences and Disagreements were resolved through discussion to come to an agreement.

Risk assessment tool named Cochrane9 was used to assess the quality of the included studies. There are 7 basic aspects in total: Random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective outcome reporting, and other bias. The tool can help assess and detect varied bias of the studies objectively and completely.

Statistical analysis

Weighted mean differences(WMD‰with 95% confidence interval(CI) were calculated to assess effect size for the merge of continuous variables. Odds ratios (ORs) with 95% confidence interval(CI) was used as effect size for the merge of classified variable. Heterogeneity among trials was assessed using the statistic Cochrane Q with significance set at p<0.05 and I2 test (I2>50%) 10. If heterogeneity was limited according to forest plotting, we used the Mantel–Haenszel fixed-effect model11; if not, the Mantel–Haenszel random effect model was used. Publication bias was evaluated by funnel plotting with Egger’s linear regression test. Data analyses were performed using RevMan5.2.


Literature Search

A flow diagram of search results can be shown in figure 1. A total of 657 references were identified from PubMedŒEmbaseŒSpringer linkŒThe Cochrane library databases. 528 references were reserved after extract repeated references. Upon outlook of the titles and abstracts, 491 references were rejected based on the rejection criteria. Upon examination of the abstracts, 21 of reserved 37 references were rejected (15 retrospectivestudies, 2 letters and 4 case series). After reading the full text, 5 references were rejected (3 be not RCTs, 1 protocol study, 1 repeated study). We cannot add more references for meta-analysis by hand search. In the end, the remaining 11 references 6, 7, 11-19were included in our meta-analysis.

Study characteristics

The results can be shown in table 1. A total of 11 references referred to random experiments (experimental group contains 731 patients, control group contains 725 patients) were included in meta-analysis. Publication years of these articles are between 2010 and 2014. Among them, 10 RCTs were separately performed in America (3 papers), Asia (5papers) and Europe (2 papers). 1 RCT was performed in different geographic region. There was no significant difference of basic data such as F/M, age, BMI, White blood cell percent-appendiceal gangrene, perforation, or abscess and so on between experimental group and control group. The methodological quality of the included trials can be shown in figure 2. All RCTs were judged as low risk of bias for all the outcome data except for the blinding of participants and personnel and blinding of outcome assessment. The total bias of the researches was low and the quality of these researches was moderate.

Clinical effect

The primary outcomes of the meta-analysis included wound infection-IAA-postoperative ileus and TPC. The secondary outcomes of the meta-analysis included operative time, LOS, PPS and analgesic use and so on.

Forest plot of pooled effect of primary outcomes can be shown in figure 3. All of the heterogeneity test results for the four indexes were I2=0ŒPž0.05Œwhich indicated that there were no statistically significant differences among different RCTs. A fixed-effects model was used to synthesize all data. Pooling the results, there were no significant differences in postoperative complications between the SILA and 3-port LA (wound infectionšOR=0.99, 95%-0.57-1.73ˆP=0.97‰›IAAšOR=1.63Œ95%-0.67-3.97ˆP=0.29‰›postoperative ileusšOR=0.74, 95%-0.25-2.16ˆP=0.58‰›TPCšOR=0.99, 95%-0.67-1.46ˆP=0.95‰). There was significant difference in operative time among different RCTsˆI2=78%ŒPœ0.00001‰. A random effect model was used to synthesize all data. The difference in operative time between the SILA and 3-port LA can be shown in figure 4. The results showed that the difference was significantˆMD=6.78ˆ3.78, 9.79‰ŒPœ0.00001‰between the SILA and 3-port LA. There was no significant difference in LOS among different RCTs. A fixed-effects model was used to synthesize all data. The results showed that LOS of SILA was similar to that of 3-port LA (MD=0ˆ-0.05, 0.04‰ŒP=0.90). In comparison of PPS, 2 papers indicated postoperative 12 hours pain scores and 3 papers reported postoperative 24 hours pain scores. So we divided into two subgroups for meta-analysis and the results showed that there was no significant difference in postoperative pain scores between the two groups. Similarly, in the comparison of analgesic useŒ2 papers studied used frequency and 3 papers studied total doses of analgesics. So we also divided into two subgroups for the analysis. Subgroup analysis indicated that there was no significant difference in the used frequency between the SILA and 3-port LA. The total doses of analgesics used in SILA was significantly higher than that in 3-port LAˆP=0.0002‰.

Publication bias

There are primary outcomes and secondary outcomes in our meta-analysis. We choose operative time which has a significant difference among different trials to test publication bias. Funnel plots were used to evaluate the possibility of a publication bias. The results were shown in figure 11. The scatter distributed shapes of the funnel plots for operative time did not reveal asymmetry, indicating no evidence of publication bias.


According to our meta-analysis from eleven RCTs, SILA demonstrated longer operative times to perform appendicitis than 3-port LA, the longer operative time of SILA may be attributed to the difficulty caused by immature technique for performing the operation1. And patients need more analgesic doses in SILA in order to feel comfortable than in 3-port LA. There were no significant differences in other clinical outcomes between the SILA and 3-port LA such as LOS, TPC, wound infection, IAA, postoperative ileus, PPS and so on. The results were similar to previous meta-analysis such as the research of Gao in 2013 and Hua in 2014 who indicated that SILA was associated with a significantly longer operative time1, 8. Although it would spend more time performing SILA, the advantages of SILA should not be ignored. SILA is suitable for appendicitis patients those demand cosmetic results because it is a “scarless” surgery. Most researchers indicated that the cosmetic scores given by patients undergoing SILA was higher than that given by patients undergoing the classic procedure1, 14. But some researchers reported that cosmetic satisfaction score and postoperative pain scores were not significantly different between SILA and 3-port LA 13. Therefore, which technique should be selected depends on patient preferences, surgeon’s decision and availability of laparoscopic instruments.

Compared with previous studies, our meta-analysis has some advantages. First, more references were included in this article which may be contributed to our search strategy compared with other meta-analysis of RCTs. We totally contained 731 patients for experimental group and 725 patients for control group. Large sample size has a higher statistical power than other related studies. Second, RCTs in this meta-analysis have middle or high qualities. Furthermore, in these studies, there were no significant differences on some basic data such as age, BMI, WBC and so on. So our conclusions may be more valid compared with former studies. Third, no publication biases were detected in these studies, which indicated that the pooled results were unbiased.

However, there are also several disadvantages in our meta-analysis which can influence our results. First, there were no enough data on postoperative pain and analgesic use, and time range and assessment of these indexes in different trials were very different. These factors caused subgroup analysis in RCTs comparing SILA with 3-port LA to be difficult and the pooled results may be biased. Second, owing to the limited data on prognostic indicators and economic indicators such as postoperative hospital charges, time to return to normal activity and patients’ satisfaction for operative scar, a comparison of SILA and 3-port LA in the aspects of economics and psychology is still lacking. So the benefit of SILA should be assessed by new randomized controlled trials and more meta-analysis.

In conclusion, the results of this meta-analysis suggest that SILA may be considered as an alternative to appendicitis compared with 3-port LA. SILA was feasible and safe for appendicitis patients. SILA does not show any obvious advantages or disadvantages over 3-port LA in primary outcomes.

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