Proposals for sample size calculation programs

The evidence-based medicine paradigm: where are we 20 years later? Part 1

The evidence-based medicine (EBM) paradigm, introduced in 1992, has had a major and positive impact on all aspects of health care. However, widespread use has also uncovered some limitations; these are discussed from the perspectives of two clinicians in this, the first of a two part narrative review. For example, there are credible reservations about the validity of hierarchical levels of evidence, a core element of the EBM paradigm. In addition, potential and actual methodological and statistical deficiencies have been identified, not only in many published randomized controlled trials but also in systematic reviews, both rated highly for evidence in EBM classifications. Ethical violations compromise reliability of some data. Clinicians need to be conscious of potential limitations in some of the cornerstones of the EBM paradigm, and to deficiencies in the literature.

Relevance of the type III error in epidemiological maps

Background

A type III error arises from a two-sided test, when one side is erroneously favoured although the true effect actually resides on the other side. The relevance of this grave error in decision-making is studied for epidemiological maps.

Results

Theoretical considerations confirm that a type III error may be large for regions with small numbers of expected cases even when no spatial smoothing has been performed. A simulation study based on infant mortality data in Austria reveals that spatial smoothing may additionally increase the risk of type III errors.

Conclusions

The occurrence of a type III error should be taken into account when interpreting results presented in epidemiological maps, particularly with regard to sparsely populated regions and spatial smoothing.

Critical Appraisal of Randomized Clinical Trials: Can We Have Faith in the Conclusions?

Randomized clinical trials (RCTs) are the most appropriate research design for studying the effectiveness of a specific intervention. Its results are considered as the highest 'level of evidence'. Published reports on RCTs have already succeeded in a peer review process, but still there can be undetected major deficiencies of the study that may question the reported outcome. It is still up to the readers to assess the quality of publications and to question if the published results apply to their patients. The major points of such a critical appraisal process are reviewed and discussed with a focus on breast cancer studies.