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.

A programme of insurance coverage for tobacco dependence treatment was examined. This was based on nicotine replacement therapy (NRT) using a nicotine gum or patch, behavioural programmes, and a free self-help kit comprising a videotape and a pamphlet published by the Agency for Health Care Policy and Research.

Primary prevention.

Cost-effectiveness analysis.

The study population comprised smokers. Smokers were defined as those who had smoked at least 100 cigarettes in their lifetime, and who smoked cigarettes every day or some days at the time of the interview. The participants were aged 18 years or older, and were enrolees of health plans. Smokers were excluded if they were pregnant, if their overall health status was poor, or if they could not use NRT because of cardiovascular diseases.

The setting was primary care within health plans. The economic study was carried out in California, USA.

The effectiveness and resource use data were gathered from January to December 1998. The price year was not reported.

The effectiveness evidence was derived from a single study.

The costing was undertaken prospectively on the same patient sample as that used in the effectiveness analysis.

Power calculations were performed in the planning phase. A sample of 600 participants in each group was required to ensure an adequate sample, which would detect a difference between the treatment and the control groups with a two-side alpha level of 0.05 and a power of 80%, anticipating about 85% participation in follow-up.

The participants were selected from 7 October to 17 December 1997 on the basis of telephone interviews conducted by a survey research firm. The firm used lists of eligible smokers, which had been provided by 16 large employers who had agreed to participate. All the employers did not cover any NRT or behavioural programmes in their HMO contracts with CIGNA and Blue Cross in 1997. The employers were available to offer the new tobacco dependence treatment benefits as part of the study. Overall, 2,385 smokers were eligible but 839 were not included in the study (mainly because they refused to participate) and 342 did not return the consent form. The final sample was thus composed of 1,204 smokers. There were 601 smokers in the intervention group who received free treatment for NRT, behavioural programme, and the free self-help kit. There were 603 smokers in the control group (receiving only the free self-help kit).

The study was a randomised controlled trial in the form of a pre-test post-test control group design. The method of randomisation was not reported. The study was carried out all over California. This potentially covered 2,600 primary care physicians in CIGNA's California HMO network and 11,700 primary care physicians in the Blue Cross of California's HMO network. The patients were followed for 1 year, from January to December 1998. The outcomes were assessed in July 1998 (6-month follow-up) and in January 1999 (one-year follow-up). Some of the participants were lost to follow-up. At the 12-month follow-up, there were still 484 participants remaining in the intervention group and 503 patients in the control group.

The basis of the clinical study (intention to treat or treatment completers only) was not reported. The analysis was conducted on the sample of patients remaining in the study after the loss to follow-up was taken into account. The primary health outcomes were:

the quit rates, defined as a report of no smoking during the previous 7 days for reasons no different from the objective of quitting smoking,

the attempts to quit, defined as an attempt made for one or more days over the 12-month period for reasons no different from the objective of quitting smoking;

the rate of watching the video or reading the pamphlet;

the rate of using bupropion;

the rate of participating in behavioural programmes; and

the rate of using nicotine gum or patch.

Adjusted odd ratios (ORs) were calculated for smokers in the intervention group, compared with the control group, over 12 months. The ORs were adjusted for factors such as the health plan, the number of cigarettes smoked per day, race, gender and income. The groups were comparable in terms of their demographics, smoking behaviours, quit history, readiness to quit, service utilisation, or physician advice to quit rates.

The quit rate was 18% in the intervention group and 13% in the control group, (p=0.04).

Attempts to quit were 55% in the intervention group and 48% in the control group, (p=0.03).

The rate of those who watched the video or read the pamphlet was 32% in the intervention group and 27% in the control group, (p=0.09).

The participation rate in the behavioural programmes was 1.2% in the intervention group and 1.1% in the control group, (p=0.8).

The rate of those who used nicotine gum and/or patch was 25% in the intervention group and 14% in the control group, (p=0.001).

The rates of those who used only nicotine gum or nicotine patch were 8.6% (gum) and 5.2% (patch) in the intervention group, respectively, and 18% (gum) and 11% (patch) in the control group. Both of these differences were statistically significant.

The rate of those who used bupropion was 4.4% in the intervention group and 7% in the control group, (p=0.07).

The rates of physician counselling did not differ between the groups.

The adjusted ORs were:

1.6 (95% confidence interval, CI: 1.1 - 2.4) for quitting smoking,

1.4 (95% CI: 1.1 - 1.8) for attempting to quit,

1.4 (95% CI: 1.0 - 1.8) for watching the video or reading the pamphlet,

2.3 (95% CI: 1.6 - 3.2) for using nicotine gum and/or patch,

1.8 (95% CI: 1.1 - 2.9) for using nicotine gum, and

1.7 (95% CI: 1.2 - 2.5) for using nicotine patches.

The programme of full coverage of tobacco dependence treatment proved to be effective in increasing the quit rates, the number of quit attempts, and the use of NRT devices.

The benefit measure used in the economic analysis was the number of participants who quit smoking. This was derived directly from the effectiveness analysis.

Discounting was irrelevant since the costs were incurred over a time period of less than 2 years. The unit costs and the quantities of resources were not reported. The cost/resource boundary adopted was that of the health insurer. The costs included in the analysis were the self-help kit, the nicotine patch or gum, and the behavioural programme. Ed's note: next sentence not understood. The authors state "The costs of bupropion are not included in the estimates, as they were not covered benefits in the study". The costs were estimated using actual data, presumably derived from the health plan insurers. The quantities of resources were gathered from January to December 1998. The price year was not reported.

Statistical analyses of the costs were not conducted.

The indirect costs were not included.

US dollars ($).

No sensitivity analyses were carried out.

See the 'Effectiveness Results' section.

The total cost for NRT and the behavioural programmes was $32,487. The cost for the self-help kit (only relevant in the control group) was $17,225.

The costs and the benefits were combined by calculating the average cost of the benefit per user who quit smoking. Assuming a smoking prevalence of 11% in the study population, the annual cost per HMO member for covering all tobacco dependence treatments (nicotine gum and patch, behavioural programme, and self-help kit) was $8.76 ($0.73 per member per month). If the self-help kit was not included, the annual cost per HMO member was $5.60 ($0.47 per member per month). The average cost of the benefit per user who quit smoking ranged from $1,495 (including the self-help kit, the nicotine patch and gum, and the behavioural programme) to $965.34 (excluding the self-help kit).

Full coverage of a tobacco dependence treatment benefit, with no patient cost-sharing, was an effective strategy for increasing quit rates and quit attempts at low cost in a population of adult smokers with employer-based health insurance.

The rationale for the selection of the comparator was clear. The intervention using the free self-help kit was used as a placebo, since published evidence indicates that the odds of quitting are the same for smokers who receive the self-help kit as for those who do not. You should assess whether it represents a widely used health intervention in your own setting.

The internal validity of the effectiveness analysis was enhanced by the random selection of the participants, the use of power calculations in the planning phase of the analysis, and statistical analyses to show the comparability of the groups. A potential confounding bias could have been represented by the fact that the number of eligible smokers who refused to participate in the study was quite high, and it was not possible to assess if the groups of those who refused and those who participated differed in some respects.

The authors acknowledged some limitations of their study. First, the time horizon of the analysis was too short to assess long-term quit rates and recidivism. Second, the study population was composed of volunteers and, therefore, the results could not be generalisable to the general population enrolled in health plans. The authors did, however, state that the entire process of using health insurance benefits is a voluntary one. Finally, the rate of use of the behavioural programme (based on the American Lung Association programmes) was quite low, as expected, and this could have had a negative impact on the overall use of NRT.

The benefit measure used in the economic analysis was derived from the effectiveness analysis. It would have been interesting had a measure relating to the impact of the intervention on patient health, such as the life-years saved, been used. Clearly, this would have required an extensive follow-up period.

The perspective of the study was that of the health insurer. All relevant categories of the costs appear to have been included in the analysis. However, the analysis of the costs was not reported in detail. The unit costs and the quantities of resources used were not reported. The costs were treated deterministically and the price year was not reported. These features limit the generalisability of the cost results.

The generalisability of the study to other settings and countries may be limited as sensitivity analyses were not conducted. The study results were, however, similar to the findings of previous research.

The authors suggest that further research should focus on the identification of the most appropriate type of behavioural programme (due to the low rate of utilisation) and on the validity of the study results to other settings.

Funded by a grant from the Robert Wood Johnson Foundation.