Response to commentaries

When guidelines need guidance: considerations and strategies for improving the adoption of chronic disease evidence by general practitioners. (GLIA): development of an instrument to identify obstacles to guideline implementation. The authors of the two commentaries [1,2] raise interesting issues about the role of Cochrane Systematic Reviews in informing international guidelines, and give us the opportunity to describe some of the ongoing efforts of Cochrane to address these challenges. For this reason, we invited Cochrane's Editor-in-Chief to join us in preparing our response. The first challenge is the mismatch between what Cochrane can offer and what the World Health Organization (WHO) actually needs; the author underlined that: 'for some questions, and for several outcomes that are key for guideline developers, no data are available from Cochrane reviews'. This is indeed true, but whether a Cochrane Review can draw useful conclusions depends upon results from primary studies being available and sufficient. One of the most frequent mismatches between the wishes of guidelines providers and what can be produced in Cochrane Reviews relates to the breadth of the PICO (Population, Intervention, Comparison, Outcomes) elements covered. It is frequently the case that guideline producers require greater breadth (e.g. multiple subgroups) than the evidence can cover without threatening its validity. The lack of well-conducted primary studies addressing relevant questions and outcomes is therefore a concern, therefore every Cochrane Review includes an 'implication for research' section which focuses on future research needs, in terms of outcomes and participants , but also setting priorities and identifying areas of uncertainty. We acknowledge that an issue of prioritization also exists for Cochrane Reviews themselves. A major effort has been made in recent years to ensure that Cochrane Reviews address the questions and uncertainties of most importance to decision-makers. Cochrane has also developed a partnership with the Guidelines International Network. Through this, we seek to work actively with guidelines producers to ensure that Cochrane Reviews meet the producers' needs to the greatest extent possible. The second challenge relates to the fact that most Cochrane Reviews include only randomized trials, although there are Cochrane groups that have always included non-randomized studies routinely. We recognize that for some outcomes, in particular those that are rare or delayed in onset, or both, the opportunity of evaluating the evidence from non-randomized studies is crucial to guide decisions. This raises additional challenges, including those of retrieving relevant studies, and evaluating the risk and direction of …