The Role of Systematic Literature Reviews

Systematic literature review is a basic scientific activity that allows scientists to view the “lay of the land” in a particular area.

A systematic review identifies, evaluates, and synthesizes research results to create a summary of current evidence that can contribute to evidence-based practice. Systematic review methodology employs the same principles and rigor required in primary research. Typically, systematic literature reviews address narrow research questions (i.e., “Does the current literature prove that treatment ‘x’ works better than treatment ‘z”?) that are typically answered using meta-analysis techniques with evidence from randomized controlled trials using similar outcome measures.

Three premises have been proposed for conducting systematic reviews: (a) to reduce large amounts of information into comprehensible units, (b) to aggregate critical information for decision-making and (c) to efficiently move from knowledge discovery to implementation.

The first premise is especially significant given the research information “overload” that has developed in the last 20 years. Emergence of international groups to promote and disseminate systematic review results such as the Campbell Collaboration, focused on social and behavioral research and the Cochrane Collaboration, focused on medical and public health, emphasize the importance of these reviews.

Systematic Review Methodology

Rigorous methodology allows systematic reviews to include (a) quantitative studies, including randomized controlled trials, qualitative studies, and single-subject studies. Additionally, the methodology continues to evolve; for example, the Agency for Healthcare Research and Quality recently issued guidance for assessing the bias risk of individual studies in systematic reviews.  Adherence to established procedures permits replication, and inclusion of a peer review process strengthens the transparency, reduces bias, and ensures a quality systematic review product.  

Systematic Scoping Review Methodology

Another type of review, the systematic scoping review, provides an alternative method to study problems that cannot be restricted to narrow research questions. Scoping reviews aim to answer broad questions about a topic, including what research questions have been asked, which groups have been studied, what types of research methodologies and measures have been used, and what the overall findings indicate.

Four common reasons for conducting a systematic scoping review are to: (a) examine the extent, range, and nature of research activity; (b) determine the value of undertaking a full systematic review; (c) summarize and disseminate research findings; and (d) identify research gaps in the literature.