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Editorial

A call to action to reshape evidence synthesis and use for nutrition policy

Mark Lawrence, Celeste Naude, Rebecca Armstrong, Lisa Bero, Namukolo Covic, Solange Durao, Davina Ghersi, Geraldine Macdonald, Harriet MacLehose, Barrie Margetts, David Tovey, Jimmy Volmink, Taryn Young
Editorial Article

Dietary risk factors are among the leading contributors to the global burden of disease.[1] Recognizing the need for nutrition policies and interventions to tackle such risk factors, the United Nations General Assembly has proclaimed 2016 to 2025 the UN Decade of Action on Nutrition.[2] Cochrane has a strong track record of producing systematic reviews of the evidence supporting nutrition policies and interventions. For example, since 2010, Cochrane has been working with the World Health Organization (WHO) to produce systematic reviews and GRADE evidence profiles in support of WHO nutrition guidelines.[3] Nutrition reviews make up 8% (641/8486) (as of July 2015) of all active reviews published in the Cochrane Database of Systematic Reviews, featuring in the work of 47 of the 53 Cochrane Review Groups that contributed to the Cochrane Library.[4]

Nutrition policies and interventions to tackle dietary risk factors fall into two broad categories: nutrition-specific, addressing the immediate causes of malnutrition (e.g. nutrient supplementation and fortification), and nutrition-sensitive, addressing the underlying causes of malnutrition (e.g. agricultural or social support programmes).[5] The profile of nutrition reviews in the Cochrane Database of Systematic Reviews is dominated by nutrition-specific interventions; 50% of nutrition reviews address nutrient supplementation alone.[4] Similar domination has been reported with the profiles of nutrition policies and guidelines recorded in the WHO e-Library of Evidence for Nutrition Actions (eLENA), and with the implementation of nutrition actions listed in the WHO Global database on the Implementation of Nutrition Action (GINA).[6] Nutrition-specific interventions may constitute appropriate responses for some micronutrient deficiency problems, but nutrition-sensitive interventions may be equally, or more, effective in combating these problems, as well as being better suited to tackling dietary imbalances associated with diet-related chronic diseases and obesity. Reviews of nutrition-sensitive interventions can be particularly relevant and highly sought after. For example, the review by Liz Waters and her team on interventions for preventing obesity in children is one of the most downloaded reviews in the Cochrane Library and has been cited by 194 articles (as of November 2016).[7]

Although individual nutrition reviews may be providing high-quality evidence, collectively they are likely to be skewing the body of evidence available to inform nutrition policies and interventions. A skewed body of evidence risks putting in motion a self-perpetuating 'evidence synthesis <-> nutrition policy and intervention’ cycle. A relatively strong evidence base to inform nutrition-specific policies and interventions could lead to nutrition-specific interventions being more likely to be implemented and evaluated, compared with nutrition-sensitive interventions, and the cycle would continue. There is a need to reshape evidence synthesis and its use in nutrition policy, particularly in relation to the following Cochrane activities:

1. Priority-setting: Research questions aligned with nutrition-specific policies and interventions are receiving more attention than those aligned with nutrition-sensitive policies and interventions.

2. Methods: Conventional evidence synthesis approaches are based on reductionist methods, which are relatively well suited for specifying and measuring relationships between single nutrients and single physiological outcomes characteristic of nutrition-specific interventions. Conversely, nutrition-sensitive interventions require the development of methods for investigating complex nutrition interventions.[8,9] Such methods need to take into account the conceptual, governance, and political challenges associated with the causes of these problems.[10,11]

3. Governance: The observed evidence synthesis dynamics are set against persistent concerns about potential conflicts of interest and how to manage relationships with the private sector, particularly in the context of concerns about research agenda distortion and framing effects.[12-14]

4. Capacity: Capacity constraints in conducting nutrition systematic reviews and using evidence to inform policy are particularly apparent in low- and middle-income countries.

Responding to the need to reshape evidence and its use and to ensure that nutrition polices are designed to tackle contemporary nutrition problems, a Symposium on Nutrition and Evidence for Policy and Practice was convened in Vienna, Austria, as part of the 23rd Cochrane Colloquium in 2015 (2015.colloquium.cochrane.org). The symposium explored how Cochrane might best take a proactive role in reforming evidence use in nutrition policy so as to be more relevant, transparent, and responsive to decision makers globally. Sixty people from a range of sectors and countries participated in the symposium, with presentations by members of the Cochrane Central Executive, the WHO, and national organizations, and by experts in systematic reviews and nutrition policy. The presentations led into an interactive workshop session during which symposium participants joined one of four groups to discuss an allocated question. The four overarching statements and priority actions prepared in response are documented in Table 1 and form the basis of this call to action.

Table 1. Overarching statements and priority actions for Cochrane to reshape evidence synthesis and use for nutrition policy

ED000118 Table 1

We call on Cochrane to implement the actions listed in Table 1. The recent establishment of a Cochrane Nutrition Field (nutrition.cochrane.org) provides an opportunity to progress this call to action. The Field's objectives are to:

1. Increase the coverage, quality, and relevance of Cochrane Reviews of nutrition, through:

  • identifying priority topics and gaps in Cochrane nutrition evidence;
  • identifying and linking editors, peer reviewers, and authors with nutrition content and methodological expertise with groups conducting reviews; and
  • sourcing funding and technical resources to support review teams.

2. Increase the impact of Cochrane nutrition reviews, through:

  • building strong relationships with other Cochrane entities and stakeholders;
  • increasing visibility of nutrition reviews in the Cochrane Library;
  • identifying Cochrane nutrition reviews that can be disseminated;
  • building capacity of researchers and decision-makers to use evidence from reviews; and
  • promoting the use of Cochrane nutrition reviews to inform the primary research agenda and new reviews needed.

3. Strengthen methods to conduct Cochrane nutrition reviews, through:

  • highlighting methodological strengths and limitations of existing reviews;
  • enhancing methodology; and
  • promoting activities to improve quality and reporting of primary nutrition research.

Members of Cochrane Nutrition have begun strengthening existing networks and partnerships to carry out this work. Cochrane Nutrition is based in South Africa and will seek input from within Cochrane as well as from partners outside of Cochrane. Those interested in participating in furthering this agenda are encouraged to visit nutrition.cochrane.org and get involved.