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Systematic and Systematic-like Reviews

CATs - what are they?

A CAT (Critically Appraised Topic) is a short summary of the best available evidence on a focused question.  It is a shorter, less rigorous type of systematic review, providing an assessment of what is known about an intervention or issue by searching and appraising relevant studies.

Because it is faster than a full SR, a CAT does have limitations in terms of comprehensiveness and so is much more prone to selection bias than a systematic review or a rapid review.  But they have an important role to play in supporting evidence based practice – identifying gaps in the knowledge, quickly scoping the literature and informing policy.

CATs have been used since the 1990s, mainly in the fields of veterinary science, physiotherapy, occupational therapy, dermatology, urology, radiology, nursing, business management and education.

Parts of a CAT

Like any type of systematic review, a certain methodology should be followed. Even though CATs are quick, compared to other reviews, they should still follow these steps:

  1. Define a clear, concise and focused question – use a search framework such as PICO to help you with this.
  2. Develop a search strategy – identify search terms, work out how to combine them and select a limited number of appropriate databases.
  3. Identify the relevant studies that help answer your question.
  4. Critically appraise the located evidence – describe and appraise the included studies. (Often the appraisal is limited to the methodological appropriateness of each study).
  5. Summarise your findings – what’s the “bottom line” suggested by the evidence?  

Further information

Have a look at these excellent articles and reports from the fields of veterinary science, dermatology, business management and physiotherapy:

And here are a couple of examples of published CATs: