A journey into clinical evidence: from case reports to mixed treatment comparisons

proceedings Why bother with clinical evidence? Medical decision making can be based on several approaches. Indeed , evidence based medicine represents just one of the several conceivable means to decide how to manage patients. confidence can all guide (or misguide) clinical decisions instead of evidence (1). Nonetheless, it now appears clear that prior clinical evidence, disseminated through peer-review publication, is the only viable approach to foster improvements in the delivery of health care (2). Moving through the evidence based medicine hierarchy: bottom-up or top-down? The hierarchy of evidence based medicine moves from in vitro studies , animal studies, case reports, and case series to observational clinical studies and randomized clinical trials (Figure 1) (3). Accordingly , in the context of secondary research (4), progressively greater emphasis is placed on editorials, reviews, systematic reviews, study level meta-analyses, and patient level meta-analyses (3). Practice guidelines occupy a unique seat in the feast, as their actual role largely depend on the quality of data gathering which lies behind the guideline itself, and on the specific agenda of the drafting committee (5). A new entry in the evidence based medicine scenario is the network meta-analysis, most recently renamed mixed treatment comparison. This type of meta-analysis, always stemming from a prior systematic review, includes both direct and indirect comparison studies, borrowing appropriately from the latter to reinforce the former. It is based on a straightforward statistical concept (Figure 2) (6-7), but may also exploit sophisticated statistical methods, including Bayesian hierarchical models (8).