Ten simple rules for interpreting and evaluating a meta-analysis

A systematic review with meta-analysis is often considered the highest level of evidence in ranking the literature [1].The term "systematic review" refers to the overall publication, while the term "meta-analysis" indicates that the review includes a statistical synthesis of results from at least 2 of the included studies [2].Not all systematic reviews include a meta-analysis, but meta-analyses are always within a systematic review.There are different types of metaanalyses in which statistical analysis can be performed, including network meta-analysis and Bayesian meta-analysis [3].While these meta-analysis methods can vary, the majority are "variations on a weighted average of the effect estimates from the different studies [2]."Their purpose is to present structured and statistical methodologies to synthesize evidence that can be used to make informed decisions, and, ideally, they include a large sample size of studies that can be summarized to answer a research question [4].For readers, a properly conducted meta-analysis with a structured and transparent approach can provide multiple benefits over other literature reviews, such as reduced bias, enhanced generalizability, increased statistical power, and overall providing efficient knowledge dissemination, and informing design of future research [1,5].Meta-analyses provide important syntheses of published study data for evidence-based practice, research, and teaching.A recent summary paper is available on how to conduct and write a meta-analysis paper, [6] but guidance on reading and interpreting meta-analyses is scattered across many publications in various disciplines.This paper focuses on simple rules for scholars or trainees to refer to when determining if a meta-analysis is high quality.These 10 simple rules provides guidance on reading and interpreting meta-analyses, in order, from the introduction of the paper through the methods, results, and analyses, so readers can determine if the research they are evaluating contains high-quality and reliable evidence for research or practice. Rule 1: Gather and understand prerequisite contextWhen starting to read a meta-analysis, the importance of the topic and the review question are critical and should be defined in the beginning paragraphs of the paper, so the audience can carefully evaluate them within the context of the published paper, checking the quality of the methodology as well as the merit of the study [4].Look for the rationale to focus on the research question, be well defined, and include all elements of the question or hypothesis, such as the population(s), intervention(s) or exposure(s), comparison group(s) if any, and the