Inter-observer agreement on levels of evidence in radiology articles

Levels of evidence (LE) are established through a hierarchical classification of studies according to their design. At present, there are many heterogeneous LE classifications, and this hampers their applicability. Our study aims to identify which LE classification has the best interobserver concordance for radiology articles. For this purpose, an interobserver agreement analysis were performed on 105 original articles applying two NE scales (Oxford Center of Evidence Based Medicine (OCEBM) y National Health and Medical Research Council (NHMRC)). The inter-rater agreement of the LE assigned after reading the abstracts was good when using the OCEBM scale (K = 0.679), and somewhat lower with the NHMRC (K = 0.577 -moderate-). All differences were statistically significant (P < .000). So, in conclusion, of the two scales analysed (OCEBM and NHMRC), the OCEBM led to the strongest level of inter-rater agreement.

[Key aspects in interpreting clinical trials in radiology]

A clinical trial is an experimental study to evaluate the efficacy and safety of a treatment or diagnostic technique in human beings. To ensure the methodological quality of a clinical trial and the validity of its results, various checklists have been elaborated to identify biases that could invalidate its conclusions. This article focuses on the points we need to consider in the critical evaluation of a clinical trial. We can usually find this information in the "materials and methods" and "results" sections of articles. Randomization, follow-up (or analysis of losses), blinding, and equivalence between groups (apart from the intervention itself) are some key aspects related to design. In the "results" section, we need to consider what measures of clinical efficacy were used (relative risk, odds ratio, or number needed to treat, among others) and the precision of the results (confidence intervals). Once we have confirmed that the clinical trial fulfills these criteria, we need to determine whether the results can be applied in our environment and whether the benefits obtained justify the risks and costs involved.

[The six steps necessary in elaborating critically appraised topics]

Different types of critically appraised topics (CATs) can be elaborated in diagnostic imaging: comparison of diagnostic tests, evaluation of techniques for early detection (screening), economical analyses, or therapeutic aspects, among others. Their design will vary in function of the question they aim to answer. For example, for treatment evaluation, clinical trials are the best, but if there are secondary studies (systematic reviews or meta-analyses) that synthesize information from several studies, the results will be more important and the scientific conclusions will be more relevant. Regardless of the study design used, the elaboration of a CAT will involve six steps: 1) question; 2) systematic and efficient bibliographic search; 3) levels of evidence (choosing the articles that have the best level); 4) critical reading of the articles chosen; 5) applying conclusions to the context, and 6) recommendations. In this article, we will describe these steps and the nuances for different types of studies in each step.

[Critically appraised topics (CATs): a new publishing opportunity in Radiología]

Physicians need fast access to quality information about the best diagnostic tests and treatments in each case. To meet this need, a new publishing format has emerged. Critically appraised topics (CATs) are elaborated following the five steps of evidence-based medicine. CATs are structured summaries of research articles that deal with a specific clinical query, presenting a critical evaluation of the best evidence available to support the validity of the available options. CATs have proven useful in teaching evidence-based radiology and this publishing format is becoming more common. Radiology CATs can be found on medical websites and in journals, including those dedicated to general medicine as well as those specifically dedicated to radiology. Radiología encourages the publication of CATs because we consider that they can be useful for daily decision making.