Post written by Fauze Maluf-Filho, MD, PhD, from the Department of Gastroenterology of University of São Paulo, Institute of Cancer of University of São Paulo (ICESP-FMUSP), São Paulo, Brazil.

The focus of the study was to clarify the methodology involved in conducting a systematic review with meta-analysis (SRMA), trying to help the GIE audience to better interpret the results and detect the limitations of studies with such design.

In the last decade, there was a remarkable increase in the number of publications of SRMA in the field of gastrointestinal endoscopy. Two factors are probably involved in this increase. First, SRMA is a secondary study, ie, it employs data from primary studies. In this sense, conducting a SRMA usually involves less effort, time, and resources when compared to a clinical trial. Second, a SRMA is considered to be the best available evidence on a clinically relevant question. This fact creates a publication bias that favors SRMA, even those of low quality. Therefore, GIE readers must be aware of the limitations of SRMA and should know how to correctly interpret its results.

SRMA employs a sophisticated statistical analysis that makes it difficult to evaluate its quality. Here are some tips that help to identify a good-quality SRMA:

• It tries to answer a clinically relevant question.
• The literature search is comprehensive, transparent, and reproducible.
• The inclusion and exclusion criteria of the primary studies are clearly stated.
• Only good quality primary studies with robust control groups, clear outcomes, and other good research practices are included in the SRMA.
• The meta-analytic treatment of the data is performed only if similar studies with adequate quality are identified. Typically, uncontrolled case series or retrospective comparative studies without robust control groups should not be included.
• The authors discuss the findings of the SRMA recognizing its limitations and providing directions for future primary researches.

SRMA should be seen as a useful tool for the interpretation of the current knowledge on a relevant clinical question. Authors and editors should guard for its quality while readers should read it cautiously before translating its conclusions into the clinical arena.

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