Critically Appraised Topics

Original Editor ­ Rachael Lowe

Top Contributors - Rachael Lowe, Andeela Hafeez, Sheik Abdul Khadir and Evan Thomas

What is a Critically Appraised Topic (CAT)

A critically appraised topic (or CAT) is a short summary of evidence on a topic of interest, usually focussed around a clinical question. Defined as a brief “summary of a search and critical appraisal of the literature related to a focused clinical question, which should be kept in an easily accessible place so that it can be used to help make clinical decisions”[1].

A CAT is like a shorter and less rigorous version of a systematic review, summarising the best available research evidence on a topic. Usually more than one study is included in a CAT. When professionals summarise a single study, the outcome is a critically appraised paper (or CAP). CATs and CAPs are one way for busy clinicians to collate and share their appraisals.

Because they are client-centered and based on “real-life” clinical scenarios, CATs should appeal to clinical learners at all levels.

Key parts of a CAT include:

  1. Purpose
  2. Reviewer
  3. Date of completion
  4. Date for review
  5. Well-built questions
  6. Search strategies and results
  7. Evidence retrieved
  8. Appraisal
  9. Conclusions

Why do we need CATs?

It is almost impossible for practitioners to keep up to date with all the new evidence for their field of clinical expertise.  All practitioners encounter questions that arise from real life clinical situations.  Evidence-based decision making in clinical scenarios demands time-efficient, up-to-date evidence review.  Critically appraised summaries of the best evidence for common clinical or educational questions address these needs.  The gold standard would be a systematic review, but this takes too much time and effort and is not practicable for clinicians.

CATs as part of the EBP process

CATs can form a structured part of the EBP process:

1. Develop a well-built question
2. Search for and select best evidence
3. Analyse the evidence - Write CAT
4. Apply the evidence to the clinical situation
5. Evaluating the application of the evidence - Revise CAT
6. Disseminating the findings  - Share CAT

How to Construct a CAT

  1. Identify gaps in knowledge from client encounters
  2. Translate the problem into an answerable question
  3. Formulate a well-built question using the PICO framework
  4. Search for the best available evidence
  5. Examine and critically appraise the evidence
  6. Write the CAT using our Physiopedia Template
  7. Share the CAT here on Physiopedia in the CAT Bank

Other CAT formats and approaches

There are other different purposes of producing CATs which include:

  • Answer explicit clinical question from real clinical situation.  This is the essence of EBP.
  • Appraise a recently published article that is important; or summarize an article used to provide evidence as part of a guideline

Validation Criteria for CATs[2]

  1. Is the CAT valid?
  2. Was the CAT focused by a well-built question?
  3. What was the explicit and sensible process used to identify and select the evidence?
  4. Is it unlikely that relevant studies were missed?
  5. Was the evidence appraised the best available to answer the question?
  6. Were the appropriate validity criteria applied to the evidence appraised?
  7. Are the dates clearly stated? Date of search, date of publication, date of expiry.
  8. What is the CAT’s message?
  9. How strong is the message? Is it expressed in terms likely to be helpful in clinical management?
  10. Will the CAT’s message help me in the care of my clients?
  11. Can I apply the message in my client setting, to my clients?
  12. Were all clinically important outcomes, benefits, harms and costs discussed?
  13. Is the academic or training level of the authors or commentators clearly stated?
  14. Have the authors, site developers, and sponsors disclosed all competing interests?
  15. Is there a mechanism to contact the authors?

Limitations of CATs

Individual CATs can be wrong or inaccurate.  CATs appear first as drafts without peer review.  These first drafts may contain inferior evidence, or errors of fact, calculations, or interpretation. This can be turned into educational benefit whereby CATs can be revised in clinical or student projects.

Individual CATs may have a short shelf life.  Cats can become obsolete as soon as newer, better evidence becomes available.  Without constant updating for newer, better evidence, their clinical bottom line becomes out of date.  Good quality CATs specify update date.

Individual, one-article CATs contain only a single element of the relevant research literature.  These critically appraised papers (CAPs) are not comprehensive explorations for all useful articles and non-representative of the entire body of evidence.

WCPT key note

A keynote article by World Confederation of Physical Therapy (WCPT) addresses the issue of:

  1. How to tell whether an article is worth reading -
  2. Criteria for deciding the quality of an article -
  3. Are study results good enough to be generalised -

Recent Related Research (from Pubmed)


  1. Centre for Evidence Based Emergency Medicine, last accessed 21st March 2011
  2. Dawes, M. (2005). Critically appraised topics and evidence-based medicine journals. Singapore Medical Journal, 46(9), 442.