Module Components

• Learning Activity

Topics

• Hierarchy of Evidence
• Primary Sources of Evidence
• Secondary Sources Evidence
• Evidence Appraisal

NRSG 790-Methods for Research and Evidence-Based Practice

Module 5: Overview: Critically Appraising Evidence

Secondary Sources Evidence

Secondary sources evaluate or synthesize multiple primary studies so as to draw conclusions on or present our current state of knowledge in a discipline or subject. These are typically peer-reviewed. Secondary sources often include a bibliography which may direct you back to the primary research reported in the article.

Literature, narrative, and integrative reviews are overviews of a topic and may be considered as background for a topic but do not serve as evidence.

Evidence summaries provide a synthesis of all the evidence into a single coherent document on the state of the science related to a specific topic. They are reviews of literature that may range from meta-analyses to integrative reviews. The beauty of evidence summaries is that they can improve the certainty with which clinicians can rely on the recommendations from the evidence. Review the Institute of Medicines recommendations regarding the development of evidence reviews.

The Cochrane Collaboration has been a source of strong systematic reviews since 1993. A systematic review uses a rigorous method to search, evaluate and summarize research studies (usually randomized controlled trials (RCTs), but sometimes non-randomized observational studies). Bias and random error are reduced by the use of a systematic and transparent method.

Review the Cochran Collaboration site to become familiar with the method and resources available.

Systematic Reviews and Meta-analyses are the most comprehensive investigations into the healthcare literature, which is why they are at the top of the evidence pyramid. Practice Guidelines are also secondary sources that are systematically developed from credible evidence sources and are used to assist practitioners and patients in making healthcare decisions.

Systematic Reviews are studies in which the authors ask a specific clinical question, perform a comprehensive literature search, eliminate poorly done studies, and attempt to make practice recommendations based on the well-done studies

Characteristics of a Systematic Review

• a clearly stated set of objectives with pre-defined eligibility criteria for studies;
• an explicit, reproducible methodology;
• a systematic search that attempts to identify all studies that would meet the eligibility criteria;
• an assessment of the validity of the findings of the included studies, for example through the assessment of risk of bias; and
• a systematic presentation, and synthesis, of the characteristics and findings of the included studies.
  Meta-analysis is the use of statistical methods to summaries the results of multiple independent studies. By combining information from all relevant studies, meta-analyses can provide more precise estimates of the effects of health care than those derived from the individual studies included within a review. Meta-analyses also facilitate investigations of the consistency of evidence across studies, and the exploration of differences across studies