Skip to Main Content

Occupational Therapy: Synthesize the Evidence

Resources used for researching occupational therapy topics at Bowling Green State University

Types of Synthesis

Critically Appraised Topic (CAT)

Systematic Review

Clinical Practice Guidelines

Critically Appraised Topic (CAT)

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.

CAT (Critically Appraised Topic) example with steps

Illustration in stacked column of steps for a CAT review: Question, search, evidence, appraisal, result

Brennan, M. L., Arlt, S. P., Belshaw, Z., Buckley, L., Corah, L., Doit, H., Fajt, V. R., Grindlay, D., Moberly, H. K., Morrow, L. D., Stavisky, J., & White, C. (2020). Critically Appraised Topics (CATs) in Veterinary Medicine: Applying Evidence in Clinical Practice. Frontiers in veterinary science, 7, 314.

Strength of Evidence

Strength of Evidence (Level of Certainty)

The strength of evidence provides an evaluation of how high the level of certainty is that an intervention caused the outcomes of interest. Strong strength of evidence means practitioners “should” consider using the intervention if appropriate, moderate means “could” use, and low means we do not know enough. If it is low, that does not mean you should not use the intervention, however it cannot be claimed to be evidence based.




  • Two or more Level 1 studies
  • The available evidence usually includes consistent results from well-designed, well-conducted studies. The findings as strong and they are unlikely to be strongly called into question by the results of future studies.


  • At least one Level 1 high-quality study or multiple moderate-quality studies (Level 2, Level 3, etc.)
  • The available evidence is sufficient to determine the effects on health outcomes, but confidence in the estimate is constrained by such factors as:
  • The number, size, or quality of individual studies.
  • Inconsistency of findings across individual studies.

As more information (other research findings) becomes available, the magnitude or direction of the observed effect could change, and this change may be large enough to alter the conclusion related to the usefulness of the intervention.


  • Small number of low-level studies, flaws in the studies, etc.
  • The available evidence is insufficient to assess effects on health and other outcomes of relevance to occupational therapy. Evidence is insufficient because of:
  • The limited number or size of studies.
  • Important flaws in study design or methods.
  • Inconsistency of findings across individual studies.
  • Lack of information on important health outcomes.

More information may allow estimation of effects on health and other outcomes of relevance to occupational therapy.

U.S. Preventive Services Task Force (


Systematic Review

According to the Cochrane Handbook, section 1.2.2, "a systematic review attempts to collate all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question."

The key characteristics of a systematic review are:

  • 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.

Green, S., Higgins, J.P.T., Alderson, P., Clarke, M., Mulrow, C.D., Oxman, A.D. (2008). Chapter 1: Introduction. In: Higgins, J.P.T., Green, S. (Eds.), Cochrane handbook for systematic reviews of interventions. The Cochrane Collaboration.

OT Practice Guidelines

Clinical Practice Guidelines

"The IOM (2011) defined clinical practice guidelines as "statements that include recommendations intended to optimize patient care that are informed by a systematic review of evidence and an assessment of the benefits and harms of alternative care options." Trustworthy guidelines should be based on a systematic evidence review, developed by panel of multidisciplinary experts, provide a clear explanation of the logical relationships between alternative care options and health outcomes, and provide ratings of both the quality of evidence and the strength of the recommendations."

NHLBI. About Systematic Evidence Reviews and Clinical Practice Guidelines. NIH National Institutes of Health., accessed 5/21/2024.