Impact of findings from grey literature on the outcomes of systematic reviews on interventions to prevent obesity among children: a systematic review.

Public health interventions are often implemented directly by government and so have an observational, rather than experimental, evidence base that may not be captured in traditional academic published sources. There is, therefore, a need to determine whether this grey literature is being actively sought when evaluating the effectiveness of public health interventions through systematic literature review; and also whether the inclusion of this grey literature has an impact on the conclusions of systematic literature reviews (SRs) evaluating public health interventions. This is particularly important as the findings of systematic literature reviews are increasingly used to inform public health policy decisions. Where possible, the sources used to obtain the grey literature in the included SRs will be categorised. As the prevention of childhood obesity is a major emerging public health issue in developed countries, this has been chosen as the topic for this methodological systematic review.