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Evidence-Based Practice: Find the Evidence

Find the Evidence

For most types of clinical questions, a well-done systematic review or meta-analysis of all available studies is the best level of evidence.

The following list outlines the best study methodologies to answer different clinical questions

Type of question

Ideal type of study

Therapy

Randomised control trial (RCT)

Prevention

RCT | Cohort Study | Case Control

Diagnosis

Prospective, blind controlled trial comparison to gold standard

Prognosis

Cohort study | Case Control | Case series or Case report

Etiology/Harm

RCT | Cohort study | Case control

Cost analysis

Economic analysis

 

Once you identify the study type that will best answer your PICO question, plan your search. A good search strategy should include advanced search syntax and alternative search terms. Use resources containing pre-appraised evidence, where the information you find in these have already undergone a filtering and critical appraisal process.

The Evidence Pyramid below shows the levels of evidence that can be used to answer your question and along side the appropriate Library databases available to search for your results.


This pyramid shows the reliability of  Primary and Secondary Research within the evidence hierarchy. When searching for evidence you should search for evidence at the highest level and progressively work down the pyramid  if higher levels do not exist. Critical appraisal is required for all studies used at the Primary Research Level

  • A piece of evidence's ability to guide clinical action increases as you move up the pyramid
  • Topics become more specific as you move down the pyramid.

Conducting the Search.

  • Advanced search syntax: such as truncation and wildcards, can be used to improve the results of your database searches.
  • Alternative search terms: when searching for evidence based literature, it's important to include synonyms and alternative terms to find all relevant literature. This can include words that are spelled differently overseas (e.g. paediatric and pediatric), concepts that are referred to differently (e.g. physiotherapy and physical therapy), conditions with both formal and informal names (e.g. heart attack and myocardial infarction) and terms that have changed over time (e.g. exercise induced asthma and exercise induced bronchospasm).
  • Refining a search: add limits to your results (date range, study type, etc.), add more concepts (location, age range, etc.), use broader or more general search terms.

Health Librarians are highly skilled  in assisting you with a search strategy and using the databases to retrieve valid results. For further assistance please  contact us. Alternatively our Tutorials help page provides links to tutorials for all the databases found on our website.