Surgeon factors, including technical proficiency, may be crucial in assessing the comparative effectiveness of competing interventions. In this multicenter clinical trial from Itani et al, laparoscopic repair of abdominal wall hernias was associated with lower overall complication rates (due primarily to fewer surgical site infections) and modestly shorter recovery times than was open repair. However, these benefits of laparoscopic repair were offset by more serious complications, particularly bowel injuries. Conversions to open surgery (10%) were also common and much more frequent in this trial than was reported in previous studies.1-3