buy cialis helvetica,sans-serif">This article is number 8 in a series of 21 articles on tools for evidence-informed health policymaking. Differences between health systems may often result in a policy or programme option not being feasible or acceptable in another setting. Or these may result in a programme or policy not working in the same way in another setting, or even achieving different impacts in another setting. A key challenge that policymakers and those supporting them must face therefore is the need to understand whether research evidence about policies and programmes can be applied to their setting. Systematic reviews make this task easier by summarising the evidence from studies conducted ina variety of different settings. However, many systematic reviews do not provide adequate descriptions of the features of the actual settings in which the original studies were conducted.