Literature Searching

"Critical appraisal is the process of systematically examining research to judge its trustworthiness, value and relevance in a particular context." (Burls, 2009, p. 1)

Systematic Reviews and Meta Analyses

Systematic reviews can often provide the best evidence. They research findings in thorough systematic literature searches.  But:

• The process of a rigorous systematic review can take years to complete and findings can therefore be superseded by more recent evidence.
• The methodological rigor and strength of findings must be appraised by the reader before being applied in clinical settings.
• A large, well-conducted RCT may provide more convincing evidence than a systematic review of smaller RCTs

Primary Studies

If a current systematic review isn't available, go to primary studies e.g. papers directly from the researcher who conducted the study. The table below lists optimal study methodologies for the main types of questions.

Note that the Clinical Queries filter available in  CINAHL/Medline matches the question type to studies with appropriate research designs. 

When searching primary literature, look first for reports of clinical trials that used the best research designs. Remember as you search, though, that the best available evidence may not come from the optimal study type. For example, if treatment effects found in well designed cohort studies are sufficiently large and consistent, those cohort studies may provide more convincing evidence than the findings of a weaker RCT.

• General resources
  • OpenGREY
  • Grey Literature Report in Public Health
  • Searches of organisational, governmental and professional websites
• Dissertations & theses
• Conference abstracts & proceedings​
  • Search of conference web pages
  • Hand-search of published conference proceedings
• Trials registers
  • WHO International Clinical Trials Registry Platform
  • ClinicalTrials.gov
  • Country specific registries & pharmaceutical registries
  • Other registries are available and may be worth consulting depending on your subject

Use these Critical Appraisal Tools (CATs) to help you evaluate the quality of particular types of evidence

https://pxhere.com/en/photo/1337399

• Appraising the appraisal
• Critical Appraisal: a checklist
• New evidence pyramid by Murad
• RCN: Critical Appraisal: Key Resources
• BMJ Best Practice