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Systematic reviews: an important anniversary, new reporting standards, and potential greater impact.

The year 2013 marks the 20th anniversary of the Cochrane Collaboration – arguably the global leader for methodological development, conducting and publishing intervention reviews. Many people are not, however, aware that the Cochrane Collaboration is supported by a network of 16 methods groups (including a qualitative and implementation methods group) whose remit it is to advise and support the Collaboration in the development and advancement of review methods. Review methodology has advanced significantly in the last 20 years as interventions have become increasingly complex and diverse, trial methodology has become increasingly pragmatic and adaptable for new contexts, and synthesis of qualitative evidence taking account of the views of patients and the public has gained importance. In turn, Cochrane is forging ahead with methodological developments and the 20th anniversary year includes work to develop guidance on synthesis of diverse evidence on complex interventions, and production of exemplars of innovative review methods. Coinciding with the 20th anniversary of the Cochrane Collaboration is another landmark – the publication in this issue of JAN of the RAMESES publication standards for realist syntheses and meta-narrative reviews (Wong et al. 2013a,b). These publication standards add to existing PRISMA standards for reporting quantitative systematic reviews and meta-analyses, and are designed to support JAN authors in raising the quality and depth of reporting – particularly review methods and processes (Moher et al. 2009). Insufficient depth, lack of methodological clarity, low levels of systematic processing, and insufficient contribution to knowledge are the most frequent reasons for rejecting review manuscripts. Additional publication standards are still required for other types of reviews, but nonetheless many of the key publication principles are common across different non-effectiveness review types. We look forward to receiving review manuscripts that have applied the new RAMESES standards. In addition, new more rigorously tested methodologies for the synthesis of diverse evidence in combination with new publication standards are likely to meet policy maker and practitioner demands for higher quality reviews of greater relevance to patients. A recent Lancet editorial made clear to research funders that no new research should be funded unless a systematic review has first been conducted to establish what is known and why further research is required (Clarke et al. 2010). Systematic reviews that apply or generate theory are also playing an increasingly important role in health services and nursing research. For example, a recently updated Cochrane review of Audit and Feedback (Ivers et al. 2012) showed the added value of theory when interpreting findings. The original review did not explicitly draw on theory and used ad hoc categories in the analysis, whereas the updated review used a theoryinformed analysis and support was found for the theorybased hypothesis that adding goals/targets and action plans to feedback interventions improved effectiveness (Susan Michie, personal communication). Finally, there is a need for higher quality reviews of qualitative evidence using appropriate and robust methodologies to develop theory and hypotheses. We especially welcome approaches, such as meta-ethnography, where higher quality and rich evidence from primary studies is suitable for translation, interpretation, and development of theory. The work by Malpass et al. (2009) and Campbell et al. (2011) provide good examples, and we encourage authors to think more broadly about developing syntheses to enhance theory development and/or ensure greater applicability to practice. There is, however, a preponderance of small and frequently lower quality qualitative studies on a multitude of nursing issues that present particular methodological challenges. To date, most qualitative reviews that report a synthesis of smaller lower quality studies are limited to presenting a set of synthetic themes that do not make a significant new contribution to knowledge. Methods are, however, being developed and tested to translate principles of data saturation, and making judgments about confidence in the synthetic product by combining individual study quality with an assessment of plausibility of a finding across studies. These new methodological advances will be helpful for