The effects of cigarette smoking on individual health 1 , the health service 2 and the economy 3 are well-documented. In view of this wide-ranging impact, a previous UK government funded a comprehensive National Health Service (NHS) Stop Smoking Service with a target of reducing the number of adult smokers to 21% or fewer by 2010 4 . The current Tobacco Control Plan for England includes clear goals to reduce adult smoking prevalence from 21% to 18.5%, smoking rates among 15 year olds from 15% to 12% and smoking in pregnancy from 14% to 11% by 2015 5 . The NHS is free at the point of delivery and funded by taxation.

NHS Stop Smoking Services 4 are now available throughout the NHS in England, providing counselling, behavioural support and medications to smokers wanting to quit. Smokers accessing these services are given various options 4 for the type of support and counselling they wish to receive. While most smoking cessation services offer both one-to-one support and sessions run in groups, the latter may be either open/rolling (people joining and leaving all at different stages of the quit process) or closed (all participants at the same stage of the quit process) and in some cases may be delivered in large workplaces ('workplace groups'). Support may be delivered centrally by Primary Care Trust (PCT)-based smoking cessation advisors or may be commissioned from GPs, nurses and pharmacists in the community. The majority of services have evolved their structure over time, to suit local needs, without evaluating whether the service is operating in the best possible way. These services also offer patients access to pharmacological therapies including nicotine replacement therapy (NRT), bupropion and varenicline. In the UK, NRT can be purchased from pharmacies without a prescription, and so can be provided by nurses and pharmacists providing a smoking cessation service, while the other therapies are available only with a physician's prescription.

Data are routinely collected to allow the Department of Health to evaluate the Stop Smoking Service. Quit rates are reported by the NHS Information Centre 6 by gender, age, ethnic group, pregnancy and geographical area, but not by structure of the service, which differs significantly between PCTs.

This series of service evaluations describe the resources used and outcomes associated with differently-structured services within three PCTs: Bournemouth & Poole Teaching PCT (PCT1), NHS South East Essex (PCT2) and NHS Warwickshire (PCT3).

Local service evaluations were conducted separately in three PCTs between January and September 2009 by an independent healthcare evaluation consultancy, using the same methods for each one. No approval was sought from a Research Ethics Committee nor consent from clients as it is required only for research and not service evaluations in the UK. Each Trust did however gain Trust management approval to take part in the evaluation and to release anonymised data. Locally and nationally published statistics 7 8 9 10 11 12 13 14 15 16 17 18 were used to obtain local population demographics so that the structure and outcomes of each service could be set in its local context.

A description of each service and the staff resources providing it was obtained by conducting interviews with smoking cessation service staff. The service manager was interviewed in all three PCTs to obtain information on the structure of the service, while a selection of key staff providing the service were asked for estimates of the average staff time involved in a quit attempt. Standardised interview guides for the service lead and for service representatives were used to ensure consistency between interviews, and responses were documented by the interviewer during the interview. Interviews were not audio or video recorded as the data collected was factual and was easily recorded onto a proforma.

Patient level data from each of the smoking cessation services were obtained retrospectively from 400 client records from each PCT. The first 400 clients accessing the service after 1st April 2008 were included in the review at each PCT. This represented 13.0%, 7.3% and 6.3% of all people from PCT1, PCT2 and PCT3 respectively that set a quit date from April 2008 to March 2009 with the NHS Stop Smoking Service 19 . Data were collected by PCT staff from electronic records and the DoH 'Gold standard' service monitoring forms. Anonymised-coded data on client demographics, chosen service provider and intervention and quit attempt outcomes were provided to the consultancy for analysis using Microsoft Excel™ and reporting back to each PCT.

The numbers and professions of the service provider staff interviewed varied according to the structure of the service described by the manager: in PCT1, three smoking cessation advisors, in PCT2, three advisors, four pharmacists and two practice nurses and in PCT3, three pharmacists and two practice nurses were interviewed.

This retrospective evaluation of smoking cessation services in 3 English PCTs shows that the context of these services varies widely between PCTs. The general health of the populations in these 3 PCTs did not differ widely from the national average. However, the prevalence of smoking ranged from 20% to 23%. The area covered by the PCT ranged from just 43 square miles in PCT1 to 736 square miles in PCT3, and the populations served ranged from 300,000 to over 500,000. All these differences have informed the development of the varying models of smoking cessation service in order to meet the needs of the local population.

The lower rates of smoking prevalence in PCT1, which follow several years of declining prevalence, may suggest that those who are more motivated to quit have already done so. Hence the service provided in PCT1 by specialised stop smoking advisors, with a wide choice of different interventions is needed for continuing success with remaining smokers who may have more complex needs. This need for specialist advisors is likely to become increasingly important as prevalence rates continue to be driven down.

Conversely, in PCT3, which covers a large geographical area, it is not feasible to provide group support to the widely dispersed, predominantly rural population. As such, the service is appropriately composed almost exclusively of one to one support provided by GP practices and pharmacies, with emphasis on specialist advisors providing high quality training and support to those delivering the service.

The 4-week quit rates for all types of intervention were greater than 40.0%, with overall quit rates averaging 46.8% to 63.3% across the PCTs. Quit rates varied between types of intervention, ranging from 42.6% for one to one support to 64.3% for closed groups in PCT1.

The 4-week quit rates also varied between the PCTs for similar types of intervention; e.g. one to one support produced quit rates ranging from 42.6% (PCT1) to 55.8% (PCT3), while group support quit rates ranged from 47.1% (PCT1) to 76.2% (PCT2). The quit rates for one to one support are similar to the national average for 2010 (49%) 33 . However, in terms of group support, PCT1 had quit rates (54.9%) that were generally slightly lower and PCT2 had quit rates that were slightly higher (76.2%) than the national average (64%) 34 .

The data suggest that, whilst group support can be an efficient and effective method, it does produce variable results which may depend on the type of client (e.g. more or less motivated), staff and geographical setting of the service. These factors need to be considered when planning a service model.

In addition to the structure of the service and the type of counselling provided, pharmacotherapies offer important support to those quitters wishing to utilise them. Across all PCTs, NRT was most commonly prescribed (quit rate range 40.0-54.3%), followed by varenicline (quit rate range 60.2-81.0%), and then bupropion (quit rate range 37.5-90.9%). The quit rate range for quitters using counselling alone was 35.5-56.5% across the PCTs although it is likely that these are the most motivated patients and, although the data was not collected, it would be interesting to assess whether these were also clients attempting to quit for the first time.

Clearly there are limitations within this service evaluation dataset and in future work it would be useful to collect levels of deprivation and dependence and socio-economic factors to allow statistical analysis and further conclusions to be drawn as to the most appropriate service/intervention for specific client profiles. In addition, more robust data allowing for the comparison of different models of provision is needed to enable Stop Smoking Services to offer the most cost effective service for their local population.

It is clear from the complexity of the results that quit rates associated with smoking cessation are multifactorial, with service structure, method of support delivery, healthcare professional involved and pharmacological support all playing a significant and important role in a quit attempt. The same models of service provision within different PCTs yield different quit rates. This is in line with recent research which reported substantial variation in success rates across intervention characteristics even after adjusting for smoker characteristics 35 . Clearly no single service will suit all and clients attempting to stop smoking need to be provided with support tailored to their individual needs. Patient choice and access to varied services is a key factor for consideration.

This evaluation has provided a useful benchmarking exercise, allowing for between-PCT descriptions of local service provision and patterns of service use to emerge, and highlighting areas for further investigation for potential service quality improvements. However, the findings need to be understood within the context of local health geography challenges and different client mixes. Stop Smoking Services with specialist knowledge of these factors are essential if smoking rates are to continue to be successfully reduced in future.

The data sets supporting the results of this article are held within the final evaluation report which is held by each author.

Fran Percival is employed by pH Associates Ltd, which was under contract with Pfizer for the development, management and reporting of the service evaluation. Ian Lockhart is an employee of Pfizer. The other authors declare they have no competing interests.

TM, SM and JW inputted into the evaluation design, sought and obtained Trust approval and oversaw the evaluation at each of their respective Trusts. They were also integral to the drafting of the manuscript. FP conceived of the evaluation, inputted into design and coordination and drafted the manuscript. IL inputted into the evaluation design and drafting of the manuscript. All authors read and approved the final manuscript.