After a medical librarian completes your literature search in support of a Systematic Review, the next step is Critical Appraisal. Critical appraisal involves the thorough evaluation of search results to identify the best articles on your topic. There are tools—Critical Appraisal Tools (CATs)—that can help. In this blog post, CASP will be described. CASP stands for Critical Appraisal Skills Programme, which, as you’ve probably deduced from the spelling, is a product of the UK, specifically a non-profit of the The National Health Service.

The strength of CASP is that it provides a different evaluation tool for different types of research studies, which is important since your search results will usually have a variety of study types: Randomized Controlled Trials (RCTs), Qualitative Research, Cohort Studies, Case Control Studies, and Diagnostic Studies, to name a few. Although RCTs are usually considered high level evidence, not all RCTs are created equal. The CASP tool for RCTs asks ten questions, one of which explores in detail the randomization process. For Qualitative Research, the questions focus on the validity of data collections methods (focus groups, semi-structured interviews, for example).

CASP tools, though copyrighted, are free to download for personal use.

Other CATs are available in addition to those provided by CASP. A recent article in the Journal of Clinical Epidemiology reviews some of them and concludes that “users of CATs should be careful about which CAT they use and how they use it.