Tainting by numbers - how the disadvantaged become invisible within evidence-based medicine.

'Evidence-based' is the key criterion for decision making not only in medicine and other health professions, where it originated and revolutionized what was previously subjective, opinion-based practice, but also across policy and service development. The 'evidence-based' epistemology uses the hierarchy of evidence - a qualitative ranking of information for consideration, as to its cogency - based on a biomedical view of human health. Evidence-based medicine originally proposed that it would contribute to justice by providing the means to make objective, and therefore, fair and equitable decisions, as well as helping to stop the use of ineffective treatments, thus minimizing costs. In this paper, we argue, however, that due to the epistemological ranking of evidence and its implications, only one type of question can ever be answered using this framework and that some groups are unjustly disregarded or excluded because of the limitations inherent in its epistemology; therefore, evidence-based decision making, whether in medicine, other health professions, or policy settings, using the hierarchy of evidence, in fact, can contribute to injustice. This injustice occurs through preferenced evidence generation set against a highly pressurized and competitive research environment, where funding is restricted and the mantra 'publish or perish' creates separate drivers and considerations for research design other than the research problem. We provide evidence of the lack of evidence generation for three specific minority groups and suggest that the epistemological foundations of an evidence-based strategy be revised to include measures of quality that reflect a connectedness not only between the researchers and the affected stakeholders (patient population, service providers, etc.) but also between the methodology/analysis and the problem trying to be solved. [ABSTRACT FROM AUTHOR]