Guidance

Appendix B: Summary of the methods used to develop this guidance

Appendix B: Summary of the methods used to develop this guidance

Introduction

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

All supporting documents are listed in appendix E.

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 interventions to improve the modifiable risk factors associated with pre-diabetes among black and minority ethnic groups and among lower socioeconomic groups?

The subsidiary questions were:

  • What are the most effective and cost-effective methods of raising health professionals' awareness of the groups at high risk of pre-diabetes?

  • What are the most effective and cost-effective methods of identifying communities, groups and individuals at high risk of pre-diabetes?

  • What are the most effective and cost-effective population-level interventions to prevent pre-diabetes?

  • What are the most effective and cost effective-ways of raising awareness of how to prevent pre-diabetes among high-risk groups?

  • What are the most effective and cost-effective ways of ensuring interventions are culturally sensitive and appropriate for use with communities at high risk of pre-diabetes?

  • What factors might discourage individuals, groups and communities at high risk of pre-diabetes from getting involved with preventive interventions? How might these barriers be addressed?

  • What are the most effective and cost-effective methods of helping people at high risk of pre-diabetes to improve their diet, be more physically active and manage their weight?

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

Reviewing the evidence

Effectiveness reviews

Four reviews of effectiveness were conducted (reviews 1, 2, 3 and 5).

Identifying the evidence

The evidence reviews for this guideline list the databases searched for each review. However, the general approach is outlined below.

The following databases were searched for reviews 1, 2 and 3 (from 1990 onwards):

  • British Nursing Index

  • Cumulative Index to Nursing and Allied Health Literature (CINAHL)

  • Cochrane Library

  • EMBASE

  • Evidence for Policy and Practice Information and Co-ordinating Centre Databases (EPPI Centre Databases)

  • MEDLINE

  • PsycINFO

  • Science Citation Index

  • Social Science Citation Index.

Additional searches of the grey literature were carried out and the following websites were also searched:

The following databases were searched for review 5 (from 1999 onwards):

  • Applied Social Sciences Index and Abstracts (ASSIA)

  • Cochrane Database of Systematic Reviews

  • Cumulative Index to Nursing and Allied Health Literature (CINAHL)

  • Database of Abstracts of Reviews of Effectiveness (DARE)

  • Database of Promoting Health Effectiveness Reviews (DoPHER)

  • Education Resources Information Centre (ERIC)

  • EMBASE

  • Health Management Information Consortium (HMIC)

  • HTA database (in the Cochrane Library)

  • MEDLINE

  • PsycINFO

  • Social Policy and Practice.

Other reviews

Two separate sets of research were conducted to identify and describe community-level interventions to prevent type 2 diabetes (reviews 4 and 6).

Identifying the evidence

Review 4 studied the search results from reviews 1 to 3. It also assessed grey literature identified via Google, the Internet search engine and via selected primary care trust (PCT) websites.

Review 6 involved searching the Internet and other networks used by managers and commissioners of community-level interventions to prevent type 2 diabetes. In addition, a referral questionnaire was sent to individuals or groups identified during the searches.

Selection criteria

The evidence reviews for this guideline list the inclusion and exclusion criteria for each review. Details can be found within each review. However, in general, the following applied.

Effectiveness reviews 1 to 3

Studies were included in reviews 1 to 3 if they were published since 1990 and:

  • covered people at high risk of pre-diabetes

  • included interventions to prevent pre-diabetes

  • Included interventions to help professionals support people at high risk of developing pre-diabetes

  • were conducted in the UK.

Studies were excluded if they focused on:

  • people diagnosed with pre-diabetes (impaired fasting glucose/impaired glucose tolerance) or diabetes

  • pregnant women, people younger than 18 or older than 74

  • people taking medication that increases the risk of developing type 2 diabetes

  • population-level screening

  • diagnostic testing (such as clinical tests to identify pre-diabetes)

  • diabetes risk assessment tools using, for example, body mass index (BMI) and waist circumference.

Effectiveness review 5

Studies were included in review 5 if they were reviews published in 1999 or later and covered:

  • black and minority ethnic populations and groups from a low socioeconomic background in the UK, any other EU country, the USA, Canada, Australia or New Zealand

  • a 'general' population (but only if the ethnicity and socioeconomic status of those included in the primary studies was systematically presented)

  • people clinically diagnosed with pre-diabetes or obesity

  • interventions in a range of settings to prevent pre-diabetes or type 2 diabetes (or relevant risk factors), including those aimed at reducing or preventing obesity, promoting physical activity or reducing calorie intake

  • the measurement of any relevant outcome such as physical activity or dietary behaviour.

Studies were excluded if they:

  • focused on those aged 0–17 years

  • focused on minority ethnic groups not relevant to the UK (for example, American Indians or Australian Aboriginals)

  • covered people who were clinically diagnosed with type 2 diabetes

  • primarily focused on pharmacological, surgical or individual interventions (such as counselling)

  • did not aim to change any of the key risk factors for pre-diabetes and type 2 diabetes

  • were delivered in healthcare settings

  • were not published in English.

Reviews 4 and 6

Broadly, interventions were included in review 4 if they:

  • covered activities to improve diet, increase physical activity levels or raise awareness of the risk factors for pre-diabetes

  • targeted adults from low socioeconomic backgrounds or from black and minority ethnic groups in the UK.

Quality appraisal

Included papers were assessed for methodological rigour and quality using the NICE methodology checklist, as set out in the NICE technical manual 'Methods for the development of NICE public health guidance' (see appendix E). Each study was graded (++, +, –) to reflect the risk of potential bias arising from its design and execution.

Study quality

++ 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 guidance. Each evidence statement concludes with a statement of applicability (directly applicable, partially applicable, not applicable).

Summarising the evidence and making evidence statements

The review data was summarised in evidence tables (see full reviews).

The findings from the reviews and expert reports 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 and public health collaborating centres. 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.

Cost effectiveness

There was a review of economic evaluations and an economic modelling exercise.

Review of economic evaluations

Studies were identified through the effectiveness review search strategies. The following databases were searched:

  • EconLit

  • NHS Economic Evaluation Database

  • Public Health Interventions Cost Effectiveness Database (PHICED) (obesity and physical activity).

Previous NICE guidance on obesity and physical activity was also reviewed, as was the FORESIGHT modelling work. In addition, citation searching and reference tracking was also undertaken. The database searches followed the same inclusion and exclusion criteria as were used in the associated mapping review.

Economic modelling

A number of assumptions were made which could underestimate or overestimate the cost effectiveness of the interventions (see review modelling report for further details).

An economic model was constructed to incorporate data from the reviews of effectiveness and cost effectiveness. The results of the economic model are reported in: 'Prevention of type 2 diabetes: preventing pre-diabetes among adults in high-risk groups. Report on cost-effectiveness evidence and methods for economic modelling'.

Fieldwork

Fieldwork was carried out to evaluate how relevant and useful NICE's recommendations are for practitioners and how feasible it would be to put them into practice. It was conducted with practitioners and commissioners who are involved in the prevention of pre-diabetes among adults in high-risk groups, including those working in the NHS, local government, voluntary sector and private sector.

The fieldwork comprised:

  • two focus groups carried out nationally

  • 25 telephone interviews

  • an online survey.

The main issues arising from this report are set out in the fieldwork findings section of appendix C.

The fieldwork was carried out by Word of Mouth Research Ltd.

How the PDG formulated the recommendations

At its meetings during December 2009 to February 2011, the Programme Development Group (PDG) 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

  • 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 guidance.

  • 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 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.

Where possible, recommendations were linked to evidence statements (see appendix C). Where a recommendation was inferred from the evidence, this was indicated by the reference 'IDE' (inference derived from the evidence).

The draft guidance, including the recommendations, was released for consultation in November 2010. At its meeting in February 2011, the PDG amended the guidance in light of comments from stakeholders and experts and the fieldwork. The guidance was signed off by the NICE Guidance Executive in April 2011.