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  • Describe a stepwise approach to appraising published literature

  • Understand the clinical relevance of study objectives

  • Evaluate appropriateness of design and methods for study objectives

  • Evaluate methods of analysis and interpretation of results

  • Differentiate between clinical and statistical significance in the medical literature


  • a priori

  • Clinical endpoints

  • Clinical significance

  • Composite endpoints

  • Number needed to harm

  • Number needed to treat

  • Surrogate endpoints


Critical appraisal of medical literature by clinicians as a tool to improve patient care has evolved since the late 1970s.1 It introduced a change in the practice paradigm based on knowledge and evolving medical literature rather than on traditional medical authority or anecdotal cases. Although early adoption of evidence-based medicine (EBM) was not readily accepted for various reasons, it has now become a mainstay of the way many clinicians practice. Sometimes the term “evidence-based” is used incorrectly by authors of research that is funded by for-profit agencies, including pharmaceutical manufacturers. Such research is often interpreted in favor of the industry product when compared to research funded by not-for-profit organizations.2,3 Therefore, the ability to critically evaluate medical literature empowers clinicians with enlightened skepticism and the ability to identify biases and errors including inappropriate control interventions, surrogate outcomes, publication bias, and other types of biases, misleading conclusions, and other false interpretations.

A clinician’s ability to deliver the best possible patient care by applying evidence and providing treatment based on sound scientific principles reflects the importance of critical appraisal skills in clinical practice. This chapter will provide an overview on how to critically evaluate medical literature. Beginning with evaluating the clinical research question, the chapter will provide a stepwise approach in appraising research articles. This will include evaluating study design, methods, and statistical analysis. This chapter will particularly emphasize the interpretation of results in the context of patient care. It will also provide specific considerations in evaluating therapy and harm. Lastly, it will conclude with general considerations for the clinicians regarding other biases in publications and their implications.


Although there are several variations in presenting research evidence, most articles published in the medical literature today have four sections: Introduction, Methods, Results, and Discussion (IMRaD) to help guide the reader. In addition to the above sections, a research paper usually includes an abstract and references.4


The abstract is the first part of the publication, although it is typically the last part written by the authors. Abstracts summarize, in a limited number of words, the aims of the research, the methods used to conduct the study, the results, and study conclusion. From the abstract, the reader can discern the study design and methodology including study population, intervention or exposures, and the outcomes for the primary and ...

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