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

Introduction

The reviews, commissioned reports and economic modelling 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 Interventions Advisory Committee (PHIAC) meetings provide further detail about the Committee's interpretation of the evidence and development of the recommendations.

All supporting documents are listed in appendix E and are available online.

Guidance development

The stages involved in developing public health intervention guidance are outlined in the box below.

1. Draft scope released for consultation

2. Stakeholder meeting about the draft scope

3. Stakeholder comments used to revise the scope

4. Final scope and responses to comments published on website

5. Evidence reviews and economic modelling undertaken and submitted to PHIAC

6. PHIAC produces draft recommendations

7. Draft guidance (and evidence) released for consultation and field testing

8. PHIAC amends recommendations

9. Final guidance published on website

10. Responses to comments published on website

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 PHIAC to help develop the recommendations. The overarching questions were:

1. Which interventions are effective and cost effective in helping women to quit smoking immediately before or during pregnancy and following childbirth?

2. Which interventions are effective and cost effective in encouraging partners (and 'significant others') help a woman quit smoking during her pregnancy and following childbirth?

3. Which interventions are effective and cost effective in preventing women who have quit smoking to take up the habit again during pregnancy and following childbirth?

4. Which interventions are effective and cost-effective in encouraging partners (and 'significant others') who smoke to stop smoking themselves?

5. Which interventions are effective and cost effective in encouraging the establishment of smokefree homes?

6. What factors aid delivery of effective interventions? What are the barriers to successful delivery?

7. What are the health consequences of pregnant women cutting down on their cigarette consumption as opposed to quitting?

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

Reviewing the evidence

Effectiveness reviews

Three reviews of effectiveness were conducted.

Identifying the evidence

The following databases were searched from 1990 to 2009 for: interventions that encourage smokefree homes; factors which help or discourage pregnant women who smoke to use smoking cessation interventions; and the health consequences of pregnant women cutting down as opposed to quitting.

  • Applied Social Sciences Index and Abstracts (ASSIA)

  • British Nursing Index

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

  • Embase

  • Maternity and Infant Care

  • MEDLINE

  • PsycINFO

  • Science Citation Index

  • Social Science Citation Index.

Web of Science Cited Reference and Google Scholar were used to search for citations and internal topic experts were consulted. In addition, the reference lists of papers and reviews that were retrieved in the search process (but not included in the review, due to study type) were sifted.

Selection criteria

Studies were included in the effectiveness reviews if they:

  • included women who smoked who were planning a pregnancy, were pregnant or had an infant aged less than 12 months

  • included anyone who smoked and lived in the same dwelling as a pregnant woman or one who was planning a pregnancy, or where an infant aged less than 12 months lived

  • covered interventions aimed at making homes smokefree

  • addressed factors that aided the delivery of effective interventions

  • looked at the health consequences of pregnant women cutting down, as opposed to quitting smoking.

Studies were excluded if they:

  • focused on women who did not smoke or who lived in a smokefree household

  • focused on women who smoked but were not planning a pregnancy, were not pregnant, or did not have a child aged under 12 months.

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 thought 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.

Summarising the evidence and making evidence statements

The review data were summarised in evidence tables (see full reviews and expert reports).

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 the public health collaborating centre (see appendix A). The statements reflect their judgement of the strength (quantity, type and quality) of evidence and its applicability to the populations and settings in the scope.

Expert reports

Three expert reports were conducted as follows:

Expert report 1 reviewed effective interventions for pregnant women who smoke before or during pregnancy. It identified 12 papers published between 2006 and 2009. It also included findings from the latest Cochrane review on a wider range of smoking cessation interventions for pregnant women who smoke.

Expert report 2 reviewed interventions to improve partner support and partner cessation during pregnancy. It identified18 papers published between 1990 and 2009.

Expert report 3 reviewed interventions to prevent women who have quit smoking during pregnancy and after childbirth from taking up the habit again. It identified 35 papers published between 1990 and 2009. It also included findings from the latest Cochrane review on relapse prevention.

Further details of the databases, search terms and strategies are included in each expert report.

Cost effectiveness

The economic analysis was based on a previous model developed for NICE's guidance on smoking cessation services. This included a sub-analysis of pregnant women.

Cost-effectiveness analysis

The model included additional data from the most recent updated Cochrane review of smoking cessation interventions for pregnant women (2009).

A number of assumptions were made which could underestimate or overestimate the cost effectiveness of the interventions (see review modelling report for further details). The results are reported in: 'The economic analysis of interventions for smoking cessation aimed at pregnant women'.

Fieldwork

Fieldwork was carried out to evaluate how relevant and useful NICE's recommendations were for practitioners and how feasible it would be to put them into practice. It was conducted with a wide range of practitioners who are involved in smoking cessation work with women during pregnancy and following childbirth. This included those working in maternity services, NHS stop-smoking services, smoking cessation helpline services primary care, schools and children's centres.

The fieldwork was carried out by Greenstreet Berman Ltd and comprised:

  • Eight workshops in Birmingham, London, and Manchester and involving a range of health professionals from around the country.

  • Six focus groups carried out in primary care trusts in Bristol, Dudley, Leicester, Liverpool, Manchester and Slough. .

The fieldwork was commissioned to ensure there was ample geographical coverage. The main issues arising are set out in appendix C under 'fieldwork findings'. The full fieldwork report, 'Consultation on NICE draft recommendations on quitting smoking in pregnancy and after childbirth: Report to the National Institute for Health and Care Excellence', is available online.

How PHIAC formulated the recommendations

At its meeting in October 2009, PHIAC considered the evidence of effectiveness, expert reports and cost effectiveness to determine:

  • whether there was sufficient evidence (in terms of strength and applicability) to form a judgement

  • whether, on balance, the evidence demonstrates that the intervention can be effective or is inconclusive

  • where there is an effect, the typical size of effect

  • whether the evidence is applicable to the target group and context covered by this guidance.

PHIAC 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 an evidence statement(s) (see appendix C for details). 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 December 2009. At its meeting in March 2010, PHIAC amended the guidance in light of comments from stakeholders, experts and the fieldwork. The guidance was signed off by the NICE Guidance Executive in June 2010.

  • National Institute for Health and Care Excellence (NICE)