8 Summary of the methods used to develop this guideline | Weight management: lifestyle services for overweight or obese adults | Guidance

Introduction

The reviews, commissioned report 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 Programme Development Group (PDG) meetings provide further detail about the Group's interpretation of the evidence and development of the recommendations.

Key questions

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 PDG to help develop the recommendations. The overarching question was: how effective and cost effective are multi-component lifestyle weight management programmes for adults?

The subsidiary questions were:

1. How does effectiveness and cost effectiveness vary for different population groups (for example, men, black and minority ethnic or low-income groups)?

2. What are the best practice principles for multi-component lifestyle weight management programmes for adults?

3. What are the most effective and cost effective behavioural or psychological components of a lifestyle weight management programme for adults – and who might best deliver them?

4. What are the views, perceptions and beliefs of adults in relation to lifestyle weight management programmes (whether or not they use such programmes)? How can overweight and obese adults from a diverse range of backgrounds be encouraged to join, and adhere to, these programmes?

5. How can lifestyle changes and weight loss be sustained once the weight management programme has ended?

6. What barriers and facilitators affect the delivery of effective weight-management programmes for adults and how do they vary for different population groups?

7. What are the best practice principles for primary care when referring people to commercial, voluntary or community sector or self-help lifestyle weight management programmes?

8. What are the best practice principles for commissioners of lifestyle weight management services for adults?

9. What training is needed for professionals involved directly or indirectly with lifestyle weight management programmes for adults?

10. How should lifestyle weight management programmes be monitored and evaluated locally?

These questions were made more specific for each review (see reviews for further details).

Reviewing the evidence

Effectiveness reviews

One review of effectiveness was conducted, split into 3 sections:

Review 1a 'The clinical effectiveness of long-term weight management schemes for adults'.
Review 1b 'How components of behavioural weight management programmes affect weight change'.
Review 1c 'Weight regain after behavioural weight management programmes'.

Identifying the evidence

The review updated and expanded on an existing review (Loveman 2011) and uses similar methods.

Ten electronic databases were systematically searched in October 2012 for randomised controlled trials of multi-component behavioural weight management programmes. See review 1 for details of the databases searched.

Reference lists were also screened and references submitted to NICE in a call for evidence.

Selection criteria

Studies were included in the effectiveness review if they:

were multi-component interventions addressing physical activity, dietary intake and behaviour change
were randomised controlled trials.
included at least 12 months follow-up
included a measure for weight loss (for example, weight or body mass index [BMI])
included adults aged 18 and older who were overweight or obese
were undertaken in OECD (Organisation for Economic Co-operation and Development) countries
were published in English.

Studies were excluded if they:

included children and pregnant women
included people with eating disorders
only included people with specific pre-existing medical condition such as diabetes, heart failure, uncontrolled hypertension or angina
focused on pharmacological or surgical interventions.

See review 1 for details of the inclusion and exclusion criteria.

Other reviews

One review of barriers and facilitators, referral, commissioning and training issues in relation to lifestyle weight management was conducted:

Review 2: Managing overweight and obese adults.

Identifying the evidence

Several databases and websites were searched in April 2013 for qualitative evidence, grey literature and best practice guidelines. See above for details.

Selection criteria

Studies were included in the review if they:

addressed questions included in the scope (except questions of effectiveness).
focused on adults aged 18 and older who were overweight or obese
were undertaken in the UK.

Studies were excluded if they:

included children and pregnant women
included people with eating disorders
focused on pharmacological or surgical interventions
only included people with a specific pre-existing medical condition such as diabetes, heart failure, uncontrolled hypertension or angina
focused on pharmacological or surgical interventions.

Quality appraisal

Included papers were assessed for methodological rigour and quality using the NICE methodology 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. Included studies were not evaluated on the basis of blinding.

Study quality: internal validity

++ 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.

This was based on:

randomisation and allocation procedures
evidence of selective reporting
attrition (at 12 months or at the closest point reported after 12 months, as appropriate).

Study quality: external validity

As above, external validity was rated '++', '+' or '−' based on whether:

participants were representative of the general population
the intervention needed any extraordinary efforts to implement in the UK (for example, the implementation of a particular infrastructure).

Summarising the evidence and making evidence statements

The review data were summarised in evidence tables (see the reviews in Supporting evidence).

The findings from the reviews 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 'Supporting evidence'). The statements reflect their judgment of the strength (quality, quantity and consistency) of evidence and its applicability to the populations and settings in the scope.

Commissioned report

A questionnaire covering practical and process issues was sent to known weight management providers operating in England. Responses to the survey were compiled by an independent researcher:

Practical and process issues in the provision of lifestyle weight management services for adults.

Cost effectiveness

There was a review of economic evaluations and an economic modelling exercise. See Managing overweight and obesity among adults: report on economic modelling and cost consequence analysis.

Review of economic evaluations

The review of economic evaluations was an extension of the effectiveness review (review 1). Studies were considered if they had been undertaken in an OECD country and included a cost effectiveness analysis. For a description of the search strategy and the inclusion, exclusion and quality criteria used, see review 1.

Economic modelling

An economic model was constructed to incorporate data from review 1. The results are reported in: Managing overweight and obesity among adults: report on economic modelling and cost consequence analysis.

How the PDG formulated the recommendations

At its meetings in 2013, the Programme Development Group (PDG) considered the evidence, expert testimony, commissioned report and cost effectiveness to determine:

whether there was sufficient evidence (in terms of strength and applicability) to form a judgment
where relevant, whether (on balance) the evidence demonstrates that the intervention or programme/activity can be effective or is inconclusive
where relevant, the typical size of effect (where there is one)
whether the evidence is applicable to the target groups and context covered by the guideline.

The PDG developed draft 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 effect on the target population's health.
Effect on inequalities in health between different groups of the population.
Equality and diversity legislation.
Ethical issues and social value judgments.
Cost effectiveness (for the NHS and other public sector organisations).
Balance of harms and benefits.
Ease of implementation and any anticipated changes in practice.

The PDG noted that effectiveness can vary according to whether interventions are delivered to a group or on a one-to-one basis.

Where possible, recommendations were linked to an evidence statement(s) (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).