Reading and critically appraising systematic reviews and meta-analyses: a short primer with a focus on hepatology

Evidence-Based Decision-Making 2: Systematic Reviews and Meta-Analysis

The number of studies published in the biomedical literature has dramatically increased over the last few decades. This massive proliferation of literature makes clinical medicine increasingly complex, and information from multiple studies is often needed to inform a particular clinical decision. However, available studies often vary in their design, methodological quality, and population studied, and may define the research question of interest quite differently. This can make it challenging to synthesize the conclusions of multiple studies. In addition, since even highly cited trials may be challenged over time, clinical decision-making requires ongoing reconciliation of studies which provide different answers to the same question. Because it is often impractical for readers to track down and review all the primary studies, systematic reviews and meta-analyses are an important source of evidence on the diagnosis, prognosis and treatment of any given disease. This chapter summarizes methods for conducting and reading systematic reviews and meta-analyses, as well as describes potential advantages and disadvantages of these publications.

Evidence-based decision-making 2: Systematic reviews and meta-analysis

The number of studies published in the biomedical literature has dramatically increased over the last few decades. This massive proliferation of literature makes clinical medicine increasingly complex, and information from multiple studies is often needed to inform a particular clinical decision. However, available studies often vary in their design, methodological quality, populations studied and may define the research question of interest quite differently, which can make it challenging to synthesize their conclusions. In addition, since even highly cited trials may be challenged over time, clinical decision-making requires ongoing reconciliation of studies which provide different answers to the same question. Because it is often impractical for readers to track down and review all the primary studies, systematic reviews and meta-analyses are an important source of evidence on the diagnosis, prognosis, and treatment of any given disease. This chapter summarizes methods for conducting and reading systematic reviews and meta-analyses, as well as describing potential advantages and disadvantages of these publications.

Basics of systematic reviews and meta-analyses for the nephrologist

Renal practitioners are expected to apply the best available evidence from rigorous scientific research to clinical decision-making and also for policy-making for those involved. Advances in information technology and unprecedented access to data have simplified the process for the search of best available evidence to guide practice. However, it is challenging to cope with the increasing volume of publications in nephrology and other areas of medicine. Accordingly, systematic reviews and meta-analysis have greatly facilitated best practice and effective clinical decision-making. Conducting a systematic review/meta-analysis involves a number of steps that start with protocol development and research question formulation, design and study selection criteria, followed by retrieval of potentially relevant studies, selection of those studies to be included and evaluation of a study's risk of bias. Systematic reviews and meta-analyses have both strengths and weaknesses. Many of the perceived limitations of meta-analysis are not inherent in the methodology, but actually represent deficits in the conduct or reporting of individual primary studies. With the continuous proliferation of published renal clinical studies, such publications will continue to be an important resource for clinicians and researchers in nephrology. It is therefore important for nephrologists to keep abreast of developments in this field, which requires some knowledge about how these studies are conducted, reported and how to appraise them for application to clinical practice or policy-making.

Primer on systematic review and meta-analysis

A systematic review uses an explicitly defined process to comprehensively identify all studies pertaining to a specific focused question, appraise the methods of the studies, summarize the results, identify reasons for different findings across studies, and cite limitations of current knowledge. Meta-analyses usually combine aggregate-level data reported in each primary study, which may provide a more precise estimate of the "true effect" than any individual study. However, the conclusions may be limited by between-trial heterogeneity, publication bias, or deficits in the conduct or reporting of individual primary studies.