This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.

The study examined four different tobacco control programmes that were based on free nicotine medication giveaway (nicotine replacement therapy, NRT).

In the first programme, eligible individuals were sent a voucher, redeemable at a local pharmacy, for a 2-week supply of either nicotine patches or gum (programme 1).

In the second programme, eligible individuals received a 1-week supply of nicotine patches sent to their home (programme 2).

In the third programme, eligible individuals received a 2-week supply of nicotine patches sent to their home (programme 3).

In the fourth programme, eligible smokers received a 6-week supply of nicotine patches and a follow-up phone call (programme 4).

All programmes, which were run in four counties of New York State, used the state's Smokers' Quitline to screen and register eligible smokers for the free medication. The free NRT was advertised through press releases or by holding staged press events. The release of free NRT was time-limited. All participants were contacted and mailed an instruction sheet on how to use nicotine medication, a copy of the Quitline's Break Loose stop smoking guide, and an information sheet on local Stop Smoking programmes.

Primary prevention.

Cost-effectiveness analysis.

The study population comprised adult (18 years and older), current daily smokers of at least 10 cigarettes per day who were willing to make a quit attempt in the next 7 days and who reported no contraindications for using either the nicotine patch or gum.

The setting was the community. The economic study was carried out in the USA.

The effectiveness data, resource use data and costs for the four treatment groups were gathered in 2003 and 2004. The control data were derived from a survey carried out in July 2001. The price year was not reported.

The effectiveness evidence was derived from a single study.

The costing was carried out prospectively on the same sample of patients as that used in the effectiveness study.

Power calculations, if performed, were not reported. Eligible participants were screened and registered through the New York State Smokers' Quitline. Overall, 40,090 smokers were sent NRT patches or voucher. There were 1,099 smokers in programme 1 (voucher for 2-week supply of NRT), 1,334 smokers in programme 2 (1-week supply of nicotine patches), 2,323 smokers in programme 3 (2-week supply of nicotine patches) and 35,334 smokers in programme 4 (6-week supply of nicotine patches). The external control group was selected from an earlier follow-up survey of 515 Quitline callers conducted in July 2001 in which NRT was not distributed.

This was a prospective cohort study with a historical control, which was carried out in four different counties of New York State. After 4 months, a minimum of 500 patients in each group was contacted by telephone. Overall, 2,384 patients were successfully contacted at follow-up (a 61% response rate among those selected to be interviewed): 500 each in programmes 1, 2 and 3, and 884 in programme 4. The authors stated that non-participants were slightly younger, and were more likely to be male and non-white than responders.

The analysis of the clinical study was restricted to those patients with complete follow-up data. The clinical measures used in the analysis were self-reported use of medications, number of quit attempts, and programme reach.

A successful quit was defined as a "no" response to the question "Have you smoked a cigarette, even a puff, in the last seven days?". A quit attempt was defined as a "yes" response to the question "Since you called for the free patches, have you ever stopped smoking for one day or longer because you were trying to quit smoking?".

Reach was defined in two ways: the proportion of eligible smokers within a defined area enrolled in the programme; and the observed call volume of Quitline before, during and after the giveaway promotions. Details of the calculation were reported.

The relative risks for quitting, comparing each programme with the control group, were calculated and adjusted for demographic characteristics (age, gender, race), type of health insurance, cigarette smoked per day at the time of enrolment, and use of other quit smoking methods. The baseline comparability of the study groups was not reported, but the authors stated that the characteristics of the smokers enrolled in the four programmes were, for the most part, similar to those of smokers in the general population. However, programme participants tended to smoke more heavily than smokers in the general population, owing to the requirement to smoke 10 or more cigarettes per day.

Programme reach, when defined in terms of eligible smokers, was 0.5% for the first programme, 0.8% for the second programme, 0.8% for the third programme and 4.8% for the fourth programme.

Programme reach, when defined in terms of average weekly call volume, increased dramatically with all programmes.

The proportions of smokers who reported that they had never used NRT before ranged from 63 to 73% in the four programmes. Medication use was related to the amount of medication received, but ranged from 78 to 89%. Approximately 30% of the participants reported experiencing at least one side effect due to the use of NRT.

The proportion of smokers that reported making a quit attempt ranged from 85 to 90% in the four programmes and was 82% in the control group.

The actual number of enrolees who quit was 301 in the first programme, 285 in the second programme, 558 in the third programme and 11,863 in the fourth programme.

The quit rate at 4-month follow-up was 12% in the control group, 27% with the first programme, 21% with the second programme, 24% with the third programme and 33% with the fourth programme.

The relative risk for quitting compared with the control group was:

2.9 (95% confidence interval, CI: 1.9 to 4.4) for programme 1,

2.0 (95% CI: 1.3 to 3.1) for programme 2,

2.4 (95% CI: 1.6 to 3.7) for programme 3, and

3.85 (95% CI: 2.6 to 5.7) for programme 4.

Since the CIs of quit rates for the four programmes overlapped, the four interventions could be considered similarly effective.

The number of quits attributable to the programmes was 169 for the first programme, 125 for the second programme, 279 for the third programme, and 7,770 for the fourth programme.

The effectiveness analysis showed that the four tobacco control programmes were significantly effective in improving smoking quit rates in comparison with individuals who did not receive free NRT.

The summary benefit measure was the quit rate. This was derived directly from the effectiveness analysis.

The viewpoint of the analysis was not explicitly reported. The analysis included the costs associated with marketing, purchasing and mailing out the free NRT, and the costs of registering and counselling smokers who called the Quitline. The unit costs and resource quantities were not presented. Resource use referred to the sample of patients included in the effectiveness study. The source of the costs was not explicitly stated. Discounting was not relevant as the costs were incurred during less than 2 years. The costs were gathered from 2003 to 2004 but the price year was not explicitly reported.

The costs appear to have been treated deterministically.

The indirect costs were not included in the economic analysis.

US dollars ($).

Sensitivity analyses were not carried out.

See the 'Effectiveness Results' section.

The total cost of the programmes was $46,365 for programme 1 (voucher for 2-week supply), $38,441 for programme 2 (1-week supply of nicotine patches), $96,826 for programme 3 (2-week supply of nicotine patches) and $2.7 million for programme 4 (6-week supply of nicotine patches).

The cost of the programmes per smoker enrolled was $42 in the first programme, $29 in the second programme, $42 in the third programme and $76 in the fourth programme.

A cost of zero was assumed to be associated with no free NRT.

Incremental cost-effectiveness ratios were calculated in order to combine the costs and benefits of the four programmes in comparison with no intervention.

The incremental cost per extra quit attributable to NRT was $274 for the first programme, $306 for the second programme, $347 for the third programme and $347 for the fourth programme.

All programmes offering free nicotine replacement therapy (NRT) to help quit smoking were effective in improving quit rates in comparison with no intervention in the USA. The 1-week supply of nicotine patches represented the most cost-effective strategy.

The rationale for the choice of the comparators was clear as the four programmes were actually implemented in New York State and were compared with the pattern of care delivered in the authors' setting. You should decide whether they are valid comparators in your own setting.

The effectiveness data were derived from the comparison between four prospective groups of smokers and a historical control group. This design usually has several drawbacks, but it was necessary because the study interventions and the comparator were implemented in different time periods. This might have introduced bias as factors other than the study interventions could have affected the results of the analysis. An adjusted regression analysis was performed to take into account the impact of baseline sociodemographic factors. Power calculations were not performed but a large sample of individuals was enrolled. A longer follow-up would probably have been more appropriate in terms of estimating the real quit rates. A large fraction of enrolees was lost to the follow-up assessment, and the analysis of effectiveness was restricted to those individuals who were available at follow-up. This might have reduced the representativeness of the study sample, especially given the baseline differences between those who were available at follow-up and those who were not contacted. The authors noted some limitations of the effectiveness analysis, such as the lack of validated biochemical instruments to confirm self-reported quit rates. These issues should be considered when assessing the validity of the effectiveness analysis.

Since an intervention-specific benefit measure was used, this will limit the possibility of comparing the results of the analysis with the benefits of other health care interventions. Quit rates are widely used to capture the benefits of smoking cessation programmes.

The analysis was limited to the costs associated with the programme. It assumed that the costs of the comparators were zero since the four programmes added only extra costs to existing services. The perspective chosen for the analysis was not explicitly stated. The sources of the costs were not explicitly reported. The impact of changes in cost estimates was not investigated and no sensitivity analyses were performed. The costs were presented as a macro-category and were not broken down, which limits the possibility of replicating the analysis in other settings. The period during which the costs and resource use data were gathered was reported, but a specific price year was not. The costs were treated deterministically and no sensitivity analyses were performed.

The authors did not report the results from other studies, but stated that the current clinical findings were consistent with those observed in previous clinical trials. The issue of the generalisability of the study results to other settings was not addressed, and sensitivity analyses were not carried out. Therefore, the external validity of the study is limited and results should be considered relevant only for the study context. As stated already, the key issues of the analysis appear to have been the use of a historical control group, the short follow-up period, and the lack of details around the economic analysis. The study referred to the general population of smokers and this was reflected in the authors' conclusions.

The study results support the contention that reducing access barriers to NRT could promote quitting in the general population, as the authors pointed out. However, given the limitations of the study design, caution will be required when interpreting the results of the analysis, especially over a long-term perspective. The authors also recommended that a large, randomised, controlled study should be performed to provide a better assessment of the cost-effectiveness of different NRT programmes.

Supported by the New York State Department of Health, Capital District Tobacco-Free Coalition, Erie/Niagara Tobacco Free Coalition, Rural Three for Tobacco Free Communities, Smoking and Health Action Coalition of Monroe Country, Smoke Free NOW, Southern Tier Tobacco Action Coalition, and Tobacco Free Coalition of the Finger Lakes.

Because readers are likely to encounter and assess individual publications, NHS EED abstracts reflect the original publication as it is written, as a stand-alone paper. Where NHS EED abstractors are able to identify positively that a publication is significantly linked to or informed by other publications, these will be referenced in the text of the abstract and their bibliographic details recorded here for information

Curry SJ, Grothaus LC, McAfee T, Pabiniak C. Use and cost-effectiveness smoking-cessation services under four insurance plans in a health maintenance organization. N Engl J Med 1998;339:673-9.

Miller N, Frieden TR, Liu SY, et al. Effectiveness of a large-scale free nicotine patch distribution program. Lancet 2005;365:1849-54.

Hughes JR, Shiffman S, Callas P, Zhang J. A meta-analysis of the efficacy of over-the-counter nicotine replacement. Tob Control 2003;12:21-7.