FIGURE 3. Meta-analysis of RCTs comparing prophylactic drain versus no drain after appendectomy for gangrenous or perforated appendicitis. Estimates of drain effects of each study are presented on a log scale along with the 95% CI. The weight of each study is reflected by the size of square. Studies were analyzed according to the complication end points intra-abdominal infections (A), wound infections (B), and fecal fistulas (C). The open diamond represents the global estimate of the drain effect along with the 95% CI (random-effects model). Test of heterogeneity is provided by χ²-based Q statistic.