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 use of telephone counselling services to assist smoking cessation was investigated. Smokers receiving telephone assistance were sent booklets and were provided with tailored counselling. Five sessions were available, with callers not being charged for the service. Patients not receiving telephone assistance were mailed booklets providing self-help techniques for moving through stages of cessation.

Primary prevention.

Cost-effectiveness analysis.

The study population comprised patients agreeing to attempt to stop smoking within 2 weeks of phoning the counselling service.

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

The participants for the study were recruited between 26 June and 15 November 2000. The price year was not reported.

The effectiveness data were derived from a single study.

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

No power calculations to determine the sample size were reported and no specific sample size was planned. Smokers participating in the study were recruited by a mass media promotion campaign carried out in Houston and east Texas. A total of 3,518 smokers called and 1,014 (29%) agreed attempt to quit within 2 weeks. Among this group, 463 were randomised to receive mailed self-help booklets and 551 were randomised to receive booklets and to be eligible for telephone counselling. The study group consisted of 37% men (mean age 41.7 years) and 63% women (mean age 41.9 years). The average daily smoking rate at baseline was 23.0 in the counselling group and 23.1 in the self-help group.

The study was a randomised controlled trial. The authors did not report the method of allocating the participants to the groups. However, the authors did report that the numbers of smokers in the two groups were unequal due to a failure in the randomisation programme in one week of the enrolment period. Both groups were followed for 12 months. Of the 551 callers assigned to receive counselling, 275 (50%) were successfully interviewed in the one year follow-up. Among the 463 callers assigned to receive booklets but no counselling, 204 (45%) were followed accordingly. The causes of loss to follow-up were refusal (19%), changes to unlisted or disconnected numbers (55%), and failures to answer (36%).

An intention to treat analysis of all patients randomised to receive counselling and those receiving booklets only was performed. The authors also reported the results for treatment completers only (i.e. results for those who were reached for follow-up interviews only). The primary outcome used in the analysis was the number of patients giving up smoking. The patients were interviewed, by telephone, 12 months after the presumed quit date (2 weeks after enrolment in the study). Efforts were made to contact as many participants as possible, with up to 20 call attempts if necessary. Cases who reported that they were abstinent at the time of the call and who experienced no more than five single-day slips (brief relapses) were considered to have maintained cessation.

There were no significant differences in the characteristics of smokers in the two experimental groups, or among those who did or did not enter the study. To verify self-reports, 19 study participants from both study groups were asked to provide saliva samples for nicotine testing and to confirm non-smoking status at a face-to-face interview.

If the quit rate calculation included only those who were reached for follow-up interviews, the estimated quit rates were 20.7% (57 out of 275) in the counselling group and 13.2% (27 out of 204) in the self-help group. The net increment was approximately 8%, (chi-squared test, p<0.01).

On the basis of an intention to treat analysis, the quit rate was 10.3% (57 out of 551) in the group offered counselling and 5.8% (27 out of 463) in the group receiving booklets only. The net increment was 4.5%, (chi-squared test, p<0.01).

Among the 19 study participants studied to confirm smoking cessation, 15 attended the interviews and all of them were found to be free of nicotine. These 15 participants comprised 9 of the 12 in the counselling group and 6 of the 7 in the self-help group.

The results of the study showed that access to counselling almost doubled the maintained quit rates over one year.

The measure of benefits used was the number of smokers who had managed to maintain cessation over a 12-month period.

The costs and the quantities were not reported separately. The direct costs included were those of the smoking cessation programme. These comprised staffing, fulfilment, telephone, evaluation, overhead and infrastructure costs. The costs of taking calls and mailing self-help books to smokers wanting to quit were also included in the study. The sources of the direct cost data were not reported. Discounting was not relevant since all the costs were incurred during one year. Hence, the costs were appropriately left undiscounted. The study reported the average costs. The price year was not reported.

The costs were treated as point estimates (i.e. the data were deterministic).

The indirect costs were not included in the analysis.

US dollars ($).

No sensitivity analysis was performed.

The quit rate was 10.3% (57 out of 551) in the group offered counselling and 5.8% (27 out of 463) in the group receiving booklets only. The net increment was 4.5%, (chi-squared test, p<0.01).

The average cost per client eligible for counselling was approximately $60. The average cost of taking calls and mailing self-help books to smokers was approximately $15 for each smoker served.

The costs and benefits were combined by calculating a cost-effectiveness ratio (i.e. the cost of each case of smoking cessation attributable specifically to the availability of the telephone counselling service). This ratio was calculated by dividing the average cost per client by the incremental effect on cessation rates. Thus, the direct cost for each case of one year' cessation attributable to counselling availability was approximately $1,300.

The promotion of a telephone counselling service to assist smoking cessation yielded responses from many smokers who were ready to quit. In addition, a large proportion of callers will use counselling if it is offered. The authors also concluded that access to counselling almost doubled the maintained quit rates over one year.

A justification was given for the comparator used, in that it represented current practice. You should decide if this is a widely used intervention in your own setting.

The analysis of effectiveness used a randomised controlled trial, which was appropriate for the study question. This study design also represents the 'gold' standard design when comparing different health interventions. As this was a brief report summarising the authors' findings, some information was not provided in detail. For example, it was unclear which method of allocation was used to randomise the patients into the two groups. The study sample seems to have been representative of the study population and the groups of smokers were shown to be comparable at analysis. The outcomes were analysed by both intention to treat and treatment completers only. Appropriate statistical analyses, to test for any statistically significant differences between the two groups, were undertaken.

The estimation of the benefits used in the economic analysis was obtained directly from the effectiveness analysis.

The authors did not explicitly report the perspective adopted in the economic analysis, but it would appear to have been that of the counselling service. All the cost categories relevant to this perspective seem to have been included. For the group receiving counselling, the recruitment costs for promotion to this service were not included in the analysis. These costs appear to have been small, and hence, are unlikely to have affected the authors' conclusions. The costs and the quantities were not reported separately, which will limit the generalisability of the authors' results. The sources of the unit costs and prices were not reported, but it would appear that they were derived from the authors' setting. No statistical analysis of the costs was performed, which will limit the interpretation of the study findings. Discounting was unnecessary since all the costs were incurred during one year. The date to which the prices related was not reported, which will hamper any possible reflation exercises.

The authors made appropriate comparisons of their findings with those from other studies that also found that telephone counselling services doubled the maintained quit rates. The authors did not address the issue of generalisability to other settings. The authors do not appear to have presented their results selectively and their conclusions reflected the scope of the analysis. The authors reported no further limitations. However, there appears to have been a flaw in the cost-effectiveness ratio calculated by the authors. To calculate this ratio the authors divided the average cost per client of the counselling service ($60) by the incremental effect on cessation rates (4.5%). In this incremental analysis, the authors failed to include the costs incurred by patients in the self-help group (i.e. those receiving the booklets only), which amounted to $15 per client. Hence, the incremental cost-effectiveness ratio of the telephone counselling service would be lower than that calculated by the authors, and would be around $1,000 ($45 divided by 4.5%).

The authors reported that in view of the promising results of this programme in Texas, the American Cancer Society would expand its availability to other states.

Funded by the Texas Department of Health.

Cromwell J, Bartosch WJ, Fiore MC, et al. Cost-effectiveness of the clinical practice recommendations in the AHCPR guideline for smoking cessation. JAMA 1997;278:1759-66.

Curry SJ, Grothaus LC, McAffee T, et al. Use and cost-effectiveness of smoking cessation services under four insurance plans in a health maintenance organization. New England Journal of Medicine 1998;339:673-9.

Croghan IT, Offord KP, Evans RW , et al. Cost-effectiveness of treating nicotine dependence: the Mayo Clinic experience. Mayo Clinic Proceedings 1997;72:917-24.

Oster G, Huse DM, Delea TE, et al. Cost-effectiveness of nicotine gum as an adjunct to physician's advice against cigarette smoking. JAMA 1986;256:1315-8.