LETTER TO THE EDITOR Single-Port Versus 4-Port Laparoscopic Cholecystectomy To the Editor: e read with great interest the article by Ma et al, “Randomized Controlled Trial Comparing Single-Port Laparoscopic Cholecystectomy and Four-Port Laparoscopic Cholecystectomy,”1 which appeared in the July 2011 issue of Annals of Surgery. We would like to express some concerns about the general design, results, and conclusions of this randomized controlled trial. First of all, although the authors specify that all of the surgeons involved in the trial have great experience in classic, 4-port laparoscopic cholecystectomy (CLC), none of the surgeons involved in the study have performed more than 5 single-port cholecystectomies (SPLCs), which could significantly influence the only statistically significant negative result of the comparisons of SPLC versus CLC in the study: the operative time. The learning curve and operative time in laparoscopic surgery are well-known facts proven by several studies, and SPLC is not an exception. Indeed, the same author demonstrated that operative time tends to decrease with experience; however, probably because of the limited number of cases considered in the study, the improvement in operative time did not reach a statistically significant difference. A very high number of SPLCs (14/21, 66%) were not “real” single-port procedures, because the surgeons added an extra port to safely complete the procedure. This fact can significantly influence the results, particularly regarding postoperative pain. Indeed, according to the results for postoperative pain,
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although pain at the umbilical site was comparable in both groups, 5 of 18 patients of the SPLC group reported pain in locations other than the umbilical port site, very likely due to the introduction of an extra port. Regarding the pain evaluation, it seems that the patients were not blinded to the procedure and knew whether a CLC or SPLC was performed. Lack of blinding could significantly affect the pain perception of each individual. Dressing the SPLC patients with 4 tapes would help them provide a more objective evaluation of postoperative pain. The authors stated that SPLC incurred more complications than CLC. First, the difference in complication rate between the 2 procedure types was not statistically significant. Second, although wound infection rates were similar in both groups, the remaining 3 reported complications in the SPLC group can hardly be related to the surgical technique. There was 1 retained bile duct stone requiring endoscopic retrograde colangio pancreatography extraction, and 1 postoperative hernia in a patient with ascites, which could significantly influence the development of a hernia. The third reported complication was a case of port-site hemorrhage that required hospitalization but neither transfusion nor surgical intervention; therefore, it can be assumed that the bleeding was minimal, and such minimal bleeding is often possible in standard laparoscopic procedures. The number of patients enrolled in this study seems very small for a randomized controlled trial that is searching for possible limited differences between the 2 groups. Indeed, the ongoing MUSIC trial (ClinicalTrials.gov Identifier NCT01104727) sponsored by the European Association for Endoscopic Surgery, assuming a comparable baseline morbidity rate of 5% for either CLC or SPLC and considering an upper limit
of 5% for SPLC to be equivalent (β-error 0.2 and one-side α-error 0.05, power 80%), includes 300 patients per group. In the discussion section, the author did not mention an article by Lee et al.,2 another randomized controlled trial featuring better cosmetic results for SPLC versus minilaparoscopy and no difference regarding complications or pain. In summary, we believe that the findings of this study by Ma et al are interesting; however, the conclusions reported in the summary are not supported by the results, because statistically significant differences were present only for operative time, which is influenced by the surgeon’s level of experience. None of the other results presented were statistically relevant. We agree with the authors that larger, well-designed, randomized trials are required to demonstrate differences between these 2 minimally invasive surgical techniques. Gianlorenzo Dionigi, MD, FACS Stefano Rausei, MD Renzo Dionigi, MD, FACS, FRCS (Hon Edin) Luigi Boni, MD, FACS Minimally Invasive Surgery Research Center Department of Surgical Sciences University of Insubria, Azienda Ospedaliera Macchi, Varese, Italy [email protected]
REFERENCES 1. Ma J, Cassera MA, Spaun GO, et al. Randomized controlled trial comparing single-port laparoscopic cholecystectomy and four-port laparoscopic cholecystectomy. Ann Surg. 2011;254:22–27. 2. Lee PC, Lo C, Lai PS, et al. Randomized clinical trial of single-incision laparoscopic cholecystectomy versus minilaparoscopic cholecystectomy. Br J Surg. 2010;97:1007–1012.
Disclosure: The authors did not receive any grant or funding related to this letter. The authors declare no conflicts of interest. C 2013 by Lippincott Williams & Wilkins Copyright ISSN: 0003-4932/13/26101-e0010 DOI: 10.1097/SLA.0000000000000299
e10 | www.annalsofsurgery.com
Annals of Surgery r Volume 261, Number 1, January 2015
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
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although pain at the umbilical site was comparable in both groups, 5 of 18 patients of the SPLC group reported pain in locations other than the umbilical port site, very likely due to the introduction of an extra port. Regarding the pain evaluation, it seems that the patients were not blinded to the procedure and knew whether a CLC or SPLC was performed. Lack of blinding could significantly affect the pain perception of each individual. Dressing the SPLC patients with 4 tapes would help them provide a more objective evaluation of postoperative pain. The authors stated that SPLC incurred more complications than CLC. First, the difference in complication rate between the 2 procedure types was not statistically significant. Second, although wound infection rates were similar in both groups, the remaining 3 reported complications in the SPLC group can hardly be related to the surgical technique. There was 1 retained bile duct stone requiring endoscopic retrograde colangio pancreatography extraction, and 1 postoperative hernia in a patient with ascites, which could significantly influence the development of a hernia. The third reported complication was a case of port-site hemorrhage that required hospitalization but neither transfusion nor surgical intervention; therefore, it can be assumed that the bleeding was minimal, and such minimal bleeding is often possible in standard laparoscopic procedures. The number of patients enrolled in this study seems very small for a randomized controlled trial that is searching for possible limited differences between the 2 groups. Indeed, the ongoing MUSIC trial (ClinicalTrials.gov Identifier NCT01104727) sponsored by the European Association for Endoscopic Surgery, assuming a comparable baseline morbidity rate of 5% for either CLC or SPLC and considering an upper limit
of 5% for SPLC to be equivalent (β-error 0.2 and one-side α-error 0.05, power 80%), includes 300 patients per group. In the discussion section, the author did not mention an article by Lee et al.,2 another randomized controlled trial featuring better cosmetic results for SPLC versus minilaparoscopy and no difference regarding complications or pain. In summary, we believe that the findings of this study by Ma et al are interesting; however, the conclusions reported in the summary are not supported by the results, because statistically significant differences were present only for operative time, which is influenced by the surgeon’s level of experience. None of the other results presented were statistically relevant. We agree with the authors that larger, well-designed, randomized trials are required to demonstrate differences between these 2 minimally invasive surgical techniques. Gianlorenzo Dionigi, MD, FACS Stefano Rausei, MD Renzo Dionigi, MD, FACS, FRCS (Hon Edin) Luigi Boni, MD, FACS Minimally Invasive Surgery Research Center Department of Surgical Sciences University of Insubria, Azienda Ospedaliera Macchi, Varese, Italy [email protected]
REFERENCES 1. Ma J, Cassera MA, Spaun GO, et al. Randomized controlled trial comparing single-port laparoscopic cholecystectomy and four-port laparoscopic cholecystectomy. Ann Surg. 2011;254:22–27. 2. Lee PC, Lo C, Lai PS, et al. Randomized clinical trial of single-incision laparoscopic cholecystectomy versus minilaparoscopic cholecystectomy. Br J Surg. 2010;97:1007–1012.
Disclosure: The authors did not receive any grant or funding related to this letter. The authors declare no conflicts of interest. C 2013 by Lippincott Williams & Wilkins Copyright ISSN: 0003-4932/13/26101-e0010 DOI: 10.1097/SLA.0000000000000299
e10 | www.annalsofsurgery.com
Annals of Surgery r Volume 261, Number 1, January 2015
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
