6 Summary of the methods used to develop this guideline
The reviews, primary research, commissioned reports and economic modelling report include full details of the methods used to select the evidence (including search strategies), assess its quality and summarise it.
The minutes of the Public Health Advisory Committee (PHAC) meetings provide further detail about the Committee's interpretation of the evidence and development of the recommendations.
The stages involved in developing public health guidelines are outlined in the box below.
1. Draft scope released for consultation
2. Stakeholder comments used to revise the scope
3. Final scope and responses to comments published on website
4. Evidence reviews and economic modelling undertaken and submitted to PHAC
5. PHAC produces draft recommendations
6. Draft guideline (and evidence) released for consultation
7. PHAC amends recommendations
8. Final guideline published on website
9. Responses to comments published on website
The key questions were established as part of the scope. They formed the starting point for the reviews of evidence and were used by the PHAC to help develop the recommendations. The overarching questions were:
Question 1: What individually modifiable behaviours may help children and young people to maintain a healthy weight or prevent excess weight gain?
Question 2: What individually modifiable behaviours may help adults to maintain a healthy weight or prevent excess weight gain?
Question 3: What are the most effective ways to communicate information to children, young people and adults about individually modifiable behaviours to help maintain a healthy weight or prevent excess weight gain?
These questions were made more specific for each review.
One review of effectiveness was conducted: review 1 An evidence review of modifiable diet and physical activity components and associated behaviours.
Several databases were searched in November 2013 for systematic reviews from 2005. See review 1.
Key websites were also searched for reports produced by governments, academics and industry. In addition, several databases were searched for primary studies where gaps in the evidence had been identified by systematic reviews.
Studies were included in the effectiveness review if:
they were high quality systematic reviews
they were undertaken among a general population
they considered the association between an individually modifiable behaviour and the maintenance of a healthy weight or the prevention of weight gain
they were published in English
they were primary studies that considered the association between a particular factor (meal planning, holiday weight gain and standing) and the maintenance of a healthy weight or the prevention of weight gain.
Because of the number of reviews meeting the inclusion criteria, reviews were prioritised for full consideration in the final evidence review based on the quality of the review, the publication date, the ability to address the factors being considered and the ability to add nuance to existing recommendations.
Studies were excluded if:
the interventions were undertaken in a particular setting
they focused only on people who were overweight or obese with an associated medical condition
they were non-systematic reviews.
See each review for details of the inclusion and exclusion criteria.
One review of qualitative evidence was conducted: review 2 Qualitative evidence review of the most acceptable ways to communicate information about individually modifiable behaviours to help maintain a healthy weight or prevent excess weight gain.
Studies were included in the review if:
they were primary UK-based qualitative studies
they were systematic reviews of qualitative studies (UK or non UK)
they were full text articles published in English after the year 2000.
Studies were excluded if:
they did not address the questions outlined in the scope
they addressed the treatment of obesity or management of medical conditions related to weight status.
Included systematic reviews were assessed for methodological rigour and quality using the NICE systematic review checklist and the Critical Appraisal Skills Programme (CASP) systematic review quality checklist. Primary studies were assessed using the appropriate NICE checklist, as set out in Methods for the development of NICE public health guidance. Each study was graded (++, +, −) to reflect the risk of potential bias arising from its design and execution.
++ All or most of the checklist criteria have been fulfilled. Where they have not been fulfilled, the conclusions are very unlikely to alter.
+ Some of the checklist criteria have been fulfilled. Those criteria that have not been fulfilled or not adequately described are unlikely to alter the conclusions.
− Few or no checklist criteria have been fulfilled. The conclusions of the study are likely or very likely to alter.
The evidence was also assessed for its applicability to the areas (populations, settings, interventions) covered by the scope of the guideline. Each evidence statement concludes with a statement of applicability (directly applicable, partially applicable, not applicable).
The review data were summarised in evidence tables (see the reviews).
The findings from the evidence review were synthesised and used as the basis for a number of evidence statements relating to each key question. The evidence statements were prepared by the external contractors (see the evidence statements). The statements reflect their judgement of the strength (quality, quantity and consistency) of evidence and its applicability to the populations and settings in the scope.
NICE prepared a document on maintenance of a healthy weight and prevention of weight gain in children and adults. Cost effectiveness considerations from a population modelling viewpoint instead of a review of economic evaluations and a modelling report. A modelling report was not considered necessary because the cost effectiveness of brief advice can be inferred from the estimates of cost effectiveness from previous modelling exercises on healthy weight, weight gain, overweight and obesity carried out for NICE in recent years.
At its meetings in April and June 2014, the Public Health Advisory Committee (PHAC) considered the evidence, expert reports and cost effectiveness to determine:
whether there was sufficient evidence (in terms of strength and applicability) to form a judgement
if relevant, whether (on balance) the evidence demonstrates that the intervention, programme or activity can be effective or is inconclusive
if relevant, the typical size of effect
whether the evidence is applicable to the target groups and context covered by the guideline.
The PHAC developed recommendations through informal consensus, based on the following criteria:
Strength (type, quality, quantity and consistency) of the evidence.
The applicability of the evidence to the populations/settings referred to in the scope.
Effect size and potential impact on the target population's health.
Impact on inequalities in health between different groups of the population.
Equality and diversity legislation.
Ethical issues and social value judgements.
Cost effectiveness (for the NHS and other public sector organisations).
Balance of harms and benefits.
Ease of implementation and any anticipated changes in practice.
If evidence was lacking, the PHAC also considered whether a recommendation should only be implemented as part of a research programme.
If possible, recommendations were linked to evidence statements (see the evidence for details). Where a recommendation was inferred from the evidence, this was indicated by the reference 'IDE' (inference derived from the evidence).