Does thoracoscopic esophagectomy really reduce post-operative pneumonia in all cases?

It has been said that "thoracoscopy suppresses the occurrence of pneumonia in comparison to thoracotomy", but does it reflect real clinical practice? To resolve this clinical question, we compared the results of randomized controlled trials (RCTs) and retrospective cohort studies from limited institutes (CLIs) in which a large number of high-volume centers were the main participants to those of retrospective cohort studies based on nationwide databases (CNDs) in which both high-volume centers and low-volume hospitals participated. A systematic review and meta-analysis were conducted to compare the short-term outcomes of thoracoscopic to open esophagectomy for esophageal cancer in the three above-mentioned research formats. In total, 43 studies with 21,057 patients, which included 1 RCT with 115 patients, 38 CLIs with 6,126 patients and 4 CNDs with 14,816 patients, were selected. Pneumonia was one of the most important complications. Although significant superiority in thoracoscopic esophagectomy was observed in RCTs (p = 0.005) and CLIs (p = 0.003), no such difference was seen in findings using nationwide databases (p = 0.69). In conclusion, unlike RCTs and CLIs, CNDs did not show the superiority of thoracoscopic surgery in terms of post-operative pneumonia. RCTs and CLIs were predominantly performed by high-volume hospitals, while CNDs were often performed by low-volume hospitals. In actual clinical practice including various types of hospitals, the superiority of thoracoscopic over open esophagectomy regarding the incidence of pneumonia may, therefore, decrease.