Critical appraisal of articles is a crucial part of a literature search. It aims at identifying methodological weaknesses and assessing the quality in a coherent way. The methodological assessment is based on a number of key questions that focus on those aspects of the study design that have a significant influence on the validity of the results reported and conclusions drawn. These key questions differ according to the study type, and a range of checklists can be used to bring a degree of consistency to the assessment process. The checklists for systematic reviews, randomized controlled trials, cohort studies and case-control studies discussed below were selected during several internal workshops at the KCE. The other checklists (for diagnosis studies for instance) will also be discussed.
The process of critical appraisal consists of an evaluation by two independent reviewers who confront their results and discuss them with a third reviewer in case of disagreement. However, because of feasibility it could be acceptable that one reviewer does the quality appraisal and that a second reviewer checks the other’s work.
If necessary, the authors of the evaluated study should be contacted for additional information.
The results of the critical appraisal should be reported in a transparent way.