Pneumonia after esophagectomy: a systematic review on definition heterogeneity

The reported incidence of postoperative pneumonia after esophagectomy varies widely, largely due to heterogeneity in its definition. Although standardized definitions have been proposed, their implementation remains unclear. This review aimed to assess how postoperative pneumonia is defined in esophagectomy research, to evaluate the implementation of proposed definitions, to quantify the use of formal, self-derived, and absent definitions over time. In addition, it aimed to identify the key diagnostic components used to define postoperative pneumonia, thereby supporting improved standardization of outcome reporting.

We systematically searched major medical databases for studies reporting pneumonia after esophagectomy, including publications from 2000 to 2024. Definitions were extracted and categorized as formal, self-derived, or absent. All definition components were coded into main and subcategories, summarized descriptively and analyzed for temporal trends.

Of the 1128 articles reporting postoperative pneumonia after esophagectomy, 653 (57.9%) did not report a definition, 4 (0.4%) provided an unclear definition, 284 (25.2%) used a self-derived definition, and 187 (16.6%) applied used a formal definition. 10 formal definitions were identified, and the 284 self-derived definitions contained 320 unique criteria. Most self-derived definitions combined clinical and imaging criteria (n = 211, 74.3%). Over time, the use of definitions increased, particularly the adoption of formal definitions, with the ECCG definition emerging as the most frequently applied in recent years.

Heterogeneity in the use of definition of postoperative pneumonia after esophagectomy remains to date. Given its clarity and practical applicability, we recommend broader and consistent adoption of the ECCG definition, to enhance comparability of outcomes and strengthen the quality of future research.