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

Abstract

Review question/objective 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. The review question is: What is the impact of findings from grey literature on the outcomes of systematic reviews on interventions to prevent obesity among children? Primary Review Objective is to evaluate the impact of findings from grey literature on the results of systematic reviews on prevention of childhood obesity. Secondary Review Objective is to determine the ratio of black to grey literature (definitions are provided in Background) included in the eligible systematic reviews; to determine the study design of the grey literature included in SRs. Inclusion criteria Types of participants The reviews of interest will only include studies on children aged two to 18 years without (at baseline) a diagnosis of obesity, or eating disorders, or co-morbid conditions that pre-dispose to obesity. Types of intervention(s) Public health interventions aimed at obesity prevention that may be applied at the population, community (including schools) or primary care level. Types of outcomes Primary – Obesity prevention will be measured according to body mass index (weight/height2) as calculated against a suitable growth reference e.g. relevant age and .sex growth classification standards, with classification into underweight, healthy weight, overweight, and obese categories.36-37 Outcomes will be grouped according to the type of prevention program implemented. Secondary - Ratio of black to grey eligible systematic reviews; ratio of black to grey studies included in eligible systematic reviews; study designs of grey literature included in eligible systematic reviews; sources used in eligible systematic reviews to obtain grey literature