Systematic reviews showed insufficient evidence for clinical practice in 2004: What about in 2011? the next appeal for the evidence-based medicine age

Rationale and aim The aims of the Cochrane systematic reviews are to make readily available and up-to-date information for clinical practice, offering consistent evidence and straightforward recommendations. In 2004, we evaluated the conclusions from Cochrane systematic reviews of randomized controlled trials in terms of their recommendations for clinical practice and found that 47.83% of them had insufficient evidence for use in clinical practice. We proposed to reanalyze the reviews to evaluate whether this percentage had significantly decreased. Methods A cross-sectional study of systematic reviews published in the Cochrane Library (Issue 7, 2011) was conducted. We randomly selected reviews across all 52 Cochrane Collaborative Review Groups. Results We analyzed 1128 completed systematic reviews. Of these, 45.30% concluded that the interventions studied were likely to be beneficial, of which only 2.04% recommended no further research. In total, 45.04% of the reviews reported that the evidence did not support either benefit or harm, of which 0.8% did not recommend further studies and 44.24% recommended additional studies; the latter has decreased from our previous study with a difference of 3.59%. Conclusion Only a small number of the Cochrane collaboration's systematic reviews support clinical interventions with no need for additional research. A larger number of high-quality randomized clinical trials are necessary to change the 'insufficient evidence' scenario for clinical practice illustrated by the Cochrane database. It is recommended that we should produce higher-quality primary studies in active collaboration and consultation with global scholars and societies so that this can represent a major component of methodological advance in this context. © 2012 John Wiley & Sons Ltd.

The functional biogeography of species: Biogeographical species roles of birds in Wallacea and the West Indies

Biogeographical systems can be analyzed as networks of species and geographical units. Within such a biogeographical network, individual species may differ fundamentally in their linkage pattern, and therefore hold different topological roles. To advance our understanding of the relationship between species traits and large-scale species distribution patterns in archipelagos, we use a network approach to classify birds as one of four biogeographical species roles: peripherals, connectors, module hubs, and network hubs. These roles are based upon the position of species within the modular network of islands and species in Wallacea and the West Indies. We test whether species traits - including habitat requirements, altitudinal range-span, feeding guild, trophic level, and body length - correlate with species roles. In both archipelagos, habitat requirements, altitudinal range-span and body length show strong relations to species roles. In particular, species that occupy coastal- and open habitats, as well as habitat generalists, show higher proportions of connectors and network hubs and thus tend to span several biogeographical modules (i.e. subregions). Likewise, large body size and a wide altitudinal range-span are related to a wide distribution on many islands and across several biogeographical modules. On the other hand, species restricted to interior forest are mainly characterized as peripherals and, thus, have narrow and localized distributions within biogeographical modules rather than across the archipelago-wide network. These results suggest that the ecological amplitude of a species is highly related to its geographical distribution within and across bio geographical subregions and furthermore supports the idea that large-scale species distributions relate to distributions at the local community level. We finally discuss how our biogeographical species roles may correspond to the stages of the taxon cycle and other prominent theories of species assembly. © 2013 The Authors.