Muddy waters: evidence-based policy making, uncertainty and the ‘York review’ on water fluoridation

English The systematic review has become widely recognised as an aid to evidence-based decision making in health care. Recently, there has been much interest around the value of systematic reviews in policy-making contexts. This article describes a relatively rare example of an explicit policy commitment to follow the findings of a systematic review, namely that of the efficacy and safety of the fluoridation of drinking water. We argue that although a policy-relevant systematic review may not be directly influential if its findings contradict prior beliefs and policy intent, it can be of value beyond the immediate policy response.