LETTER TO THE EDITOR Irrigation Versus Suction Alone During Laparoscopic Appendectomy for Perforated Appendicitis: A Prospective Randomized Trial To the Editor: e were truly interested in the article by St. Peter et al,1 published in Annals of Surgery of October 2012. Their work was a strong prospective study of the impact of irrigation in cases of laparoscopic appendectomies for perforated appendicitis in the pediatric population. One limitation worth of notice in their work is their estimation of the sample size. They suggested that a difference of abscess rates, moving from their known 18% at their institution to a 35% value, would require a sample size of 220 patients to obtain a power of 80%. That being said, one might certainly argue that given the frequent nature of the disease studied, a much smaller change in abscess formation rate (from 18% to 25%, for instance) might well be clinically relevant considering the costs associated with the treatment of abscess in the pediatric population. Then, a much larger sample size would have been needed to obtain the desired power of the study. Nevertheless, we still agree with the conclusion of the authors, suggesting that there are no conclusive data in favor of recommending peritoneal irrigation during laparoscopic appendectomies, as was also suggested in a recent trial in the Journal of Pediatric Surgery.2 To further support that statement, we take the opportunity to report preliminary, un-

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Disclosure: None of the authors has anything to declare relating to this letter. C 2013 Wolters Kluwer Health, Inc. All Copyright  rights reserved. ISSN: 0003-4932/13/26104-e0098 DOI: 10.1097/SLA.0000000000000448

e98 | www.annalsofsurgery.com

published data from a study at our institution. We studied the effect of peritoneal irrigation on postoperative pain in 130 adult patients with acute appendicitis (complicated or not), and although final statistical analysis is yet to be compiled, no differences were shown after examining 50 patients. More specifically, there was no difference in subjective pain measured by patients, in pain medication consumption, and in infectious complications. Our intervention protocol was somewhat similar to that used by St. Peter et al.1 We believe that these results will further support the lack of benefit from peritoneal irrigation with a different angle over the problem. In conclusion, we agree with St. Peter et al and most of the recent published literature regarding the fact that no evidence has shown any clear benefit for abdominal irrigation during laparoscopic appendectomy. Hence, we believe that this practice should be dropped. Yves Collin, MD Sandeep Mayer, MD, FRCSC Franc¸ois Mosimann, MD Facult´e de m´edecine Universit´e de Sherbrooke Sherbrooke, Quebec, Canada [email protected]

REFERENCES 1. St Peter SD, Adibe OO, Iqbal CW, et al. Irrigation versus suction alone during laparoscopic appendectomy for perforated appendicitis. Ann Surg. 2012;256:581–585. 2. Akkoyun I, Tuna AT. Advantages of abandoning abdominal cavity irrigation and drainage in operations performed on children with perforated appendicitis. J Pediatr Surg. 2012;47:1886–1890.

the results typically plateau early after enrollment and from that point forward the precision of the measurement estimates improve. As this occurs, the measures of variation decrease and P values decrease where differences exist The number established in this trial provides a fairly strong estimate of effect size from the treatment variable.1 If, as Collin et al suggested, a difference of 7% (from 18% to 25%) were seen in abscess rate, this might be a meaningful effect size; the conclusions would not be the same and such a finding would warrant further investigation or further enrollment after a known effect size had been established under equal prospective and randomized conditions. This was not the case, and effect size approached zero after 220 patients. When we look back at the data, the difference in abscess rate between groups was within 5% after 50 patients enrolled and within 2% from 100 patients onward. Not only was the abscess rate the same, the size and number of abscesses were the same, the location of abscesses were identical as were the overall hospital courses and the hospital courses for those treated for an abscess. These data are all stable for the back half of the trial, which makes it clear that the effect sizes reported for primary and all secondary outcomes are fairly reliable, and that in our system, under the same protocol, further enrollment would increase the precision of measuring clinically irrelevant effect sizes. Shawn David St. Peter, MD Children’s Mercy Hospital Department of Surgery St. Louis, MO [email protected]

REFERENCE Reply:

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lthough the delta utilized a priori provides the foundation for initiating a trial,

1. St Peter SD, Adibe OO, Iqbal CW, et al. Irrigation versus suction alone during laparoscopic appendectomy for perforated appendicitis. Ann Surg. 2012;256:581–585.

Disclosure: The authors declare no conflicts of interest and no source of funding. DOI: 10.1097/SLA.0000000000000449

Annals of Surgery r Volume 261, Number 4, April 2015

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Irrigation versus suction alone during laparoscopic appendectomy for perforated appendicitis: a prospective randomized trial.

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