Abstract: We identified 85 studies involving 9765 participants. Seventy-five trials included 8520 adults and 10 trials included 1245 children. Most studies had risk of bias issues, with attrition bias being the largest source across studies due to incomplete outcome data. In adults, pain intensity on day one was reduced by 0.75 cm on a 10 cm VAS after LA (MD -0.75, 95% CI -1.04 to -0.45; 20 RCTs; 2421 participants; low-quality evidence). Wound infections were less likely after LA (Peto OR 0.42, 95% CI 0.35 to 0.51; 63 RCTs; 7612 participants; moderate-quality evidence), but the incidence of intra-abdominal abscesses was increased following LA (Peto OR 1.65, 95% CI 1.12 to 2.43; 53 RCTs; 6677 participants; moderate-quality evidence). The length of hospital stay was shortened by one day after LA (MD -0.96, 95% CI -1.23 to -0.70; 46 RCTs; 5127 participant; low-quality evidence). The time until return to normal activity occurred five days earlier after LA than after OA (MD -4.97, 95% CI -6.77 to -3.16; 17 RCTs; 1653 participants; low-quality evidence). Two studies showed better quality of life scores following LA, but used different scales, and therefore no pooled estimates were presented. One used the SF-36 questionnaire two weeks after surgery and the other used the Gastro-intestinal Quality of Life Index six weeks and six months after surgery (both low-quality evidence). In children, we found no differences in pain intensity on day one (MD -0.80, 95% CI -1.65 to 0.05; 1 RCT; 61 participants; low-quality evidence), intra-abdominal abscesses after LA (Peto OR 0.54, 95% CI 0.24 to 1.22; 9 RCTs; 1185 participants; low-quality evidence) or time until return to normal activity (MD -0.50, 95% CI -1.30 to 0.30; 1 RCT; 383 participants; moderate-quality evidence). However, wound infections were less likely after LA (Peto OR 0.25, 95% CI 0.15 to 0.42; 10 RCTs; 1245 participants; moderate-quality evidence) and the length of hospital stay was shortened by 0.8 days after LA (MD -0.81, 95% CI -1.01 to -0.62; 6 RCTs; 316 participants; low-quality evidence). Quality of life was not reported in any of the included studies. Except for a higher rate of intra-abdominal abscesses after LA in adults, LA showed advantages over OA in pain intensity on day one, wound infections, length of hospital stay and time until return to normal activity in adults. In contrast, LA showed advantages over OA in wound infections and length of hospital stay in children. Two studies reported better quality of life scores in adults. No study reported this outcome in children. However, the quality of evidence ranged from very low to moderate and some of the clinical effects of LA were small and of limited clinical relevance. Future studies with low risk of bias should investigate, in particular, the quality of life in children.

Plain-language summary: We included 85 studies involving 9765 participants, of which 75 trials compared laparoscopic appendectomy versus open appendectomy in adults. The remaining 10 studies included only children. The evidence is current to February 2018. The main advantages of laparoscopic compared to open appendectomy were reduced postsurgical pain, reduced risk of wound infection, shorter hospital stay, and more rapid return to normal activities in adults. In contrast, laparoscopic appendectomy showed advantages over open appendectomy in wound infections and shorter hospital stay in children. Two studies reported that adults who received laparoscopic appendectomy had better quality of life two weeks, six weeks, and six months after surgery. Data from children were not available. As for disadvantages of laparoscopic appendectomy, a higher rate of intra-abdominal abscesses were identified in adults but not in children. Except for a trend towards decreased intra-abdominal abscesses after LA, the results for children were similar to those seen in adults. The quality of the evidence varied from moderate to low because of poorly conducted studies.