Introduction
The report from the Cardiovascular Health Strategy Group Building Healthier Hearts highlights the fact that smoking is the largest single cause of preventable mortality and morbidity in Ireland.¹ At the age of 65 years the life expectancy for men and women in Ireland is the lowest in the EU. SLN and Health Behaviour in School Aged Children (HBSC) undertaken by the Department of Health Promotion, National University of Ireland, Galway provide information on the prevalence of smoking in adults and school pupils.² Overall 27% of respondents in SLN were regular or occasional cigarette smokers. The HBSC found that by the age of 15-17 years approximately one third of boys and girls were regular smokers. Smoking cessation at any age is associated with risk reduction. Smoking cessation advice by a doctor in general practice can achieve one year smoking cessation rates in the region of 4-6%.³ Effectiveness is increased by the prescription of nicotine replacement therapy. Barriers have been identified which limit the effectiveness of physicians in smoking cessation efforts. These include education and training, organisational issues and drug reimbursement.⁴ Nicotine replacement therapy (NRT) has been available free of charge for medical cardholders in Ireland since April 2001. NRT therapy formulations include gum, patches and inhaled medication. There are nine such preparations which are currently available under the General Medical Services (GMS) scheme. The GMS Payments Board Report for the year ended 31/12/2002 indicates that nicotine replacement therapy was number 90 in the top 100 most commonly prescribed products under the GMS scheme. For the top 100 products in order of their total ingredient cost under the GMS scheme NRT was number 44 with an expenditure of 2,709,954 (3,260,726 including VAT and dispensing fees) which accounted for 0.63% of total expenditure for the scheme in 2002.⁵

In view of the significant increase in NRT prescribing and associated expenditure we investigated prescribing trends for NRT before and after the change in reimbursement status. We also provide data in relation to bupropion (Zyban) as it was the first prescription medication available for smoking cessation under the GMS scheme having being introduced in September 2000.

Methods
The General Medical Services (GMS) scheme provided free prescription medicines to 29.84% of the Irish population (1,168,745 patients) in 2002.

Using the GMS Payments Board prescription database we conducted a detailed analysis of NRT prescribing (ATC code N07BA) before and after April 2001 when NRT became available free of charge to medical card holders. We also determined the number of monthly prescriptions for each NRT preparation (ATC code N07BA01) and bupropion (ATC code N07BA02) together with total expenditure in all health board areas in Ireland from January to December 2002. Mean dosage, duration of therapy and age/gender distribution of NRT treatment was also obtained.

Figure 1. Prescribing of bupropion (Zyban) and NRT from Sept 2000 to Dec 2001 under the GMS scheme

Results
The prescribing trends for bupropion and nicotine replacement therapy before and after the change in reimbursement status for NRT in April 2001 is shown in figure 1. Following the introduction of NRT to the GMS a prescribing rate of 6 per 1000 patients was recorded within the first month. A marked reduction in the prescribing of bupropion occurred at this time with prescribing rates declining from 6 per 1000 patients in January 2001 to approximately 1 per 1000 patients in June 2001. We identified 49,826 patients (M:F 23,169; 26,657) who received smoking cessation products in 2002. Of these 94.6% (47,147 patients) were prescribed nicotine replacement therapy the remaining 5.4% (2,679 patients) received bupropion. Nicotine patch therapy accounted for 82.8% of all NRT dispensed, with the nicorette patch accounting for over half (50.2%) of all smoking cessation products prescribed in 2002 (table 1). Prescribing trends for NRT show the number of patients receiving such therapy is greatest for the months January and February (figure 2). Consequently, expenditure on NRT is highest in the first quarter of each year.

Figure 2.

Prescribing of NRT is greatest amongst the 25-54 year age group with peak prescribing between the ages of 35-44 years (table 2). The highest dose of nicotine patch therapy (15-21mg per day) was prescribed for the majority (73%) of all patients with only 7% of patients receiving the lower dosage. Nicotine chewing gum was prescribed for 8.2% of all patients receiving smoking cessation therapy with a mean dose of approximately 16mg per patient per day. Over three quarters (75.6%) of all patients were prescribed nicotine patch therapy for a period of less than or equal to 4 weeks. Approximately half of all patients (48.1%) received less than or equal to 2 weeks of nicotine patch therapy. Similarly for nicotine gum therapy where 77% of all patients received just one month of treatment.

Discussion
The introduction of NRT to the GMS scheme in April 2001 resulted in a significant uptake with the rate of prescribing at 6 per 1000 patients within the first month. This corresponded to a marked reduction in the prescribing of bupropion, however the decline in bupropion prescribing commenced prior to the introduction of NRT and may well have been associated with safety warnings in relation to adverse effects (e.g. seizures) and potential drug interactions (antipsychotics, antidepressants, theophylline) issued in December 2000 and April 2001.^6,7 The main form of nicotine replacement therapy utilised under the GMS scheme is the patch preparation which was prescribed for over 78% of all patients and accounted for over 80% of total expenditure on smoking cessation therapies in 2002. In contrast nicotine gum was prescribed for just over 8% of patients accounting for 7% of total expenditure on smoking cessation therapy under the GMS scheme that year. Nicotine chewing gum was the first type of nicotine replacement therapy to become widely available. Meta analysis has indicated that the use of nicotine gum in specialised clinics is effective however its use in general practice was deemed questionable.⁸

The transdermal patch is considered to have an advantage over the chewing gum preparation in that it is discreet, convenient to use, requires minimal instruction and is well tolerated both topically and systemically. Large randomised trials on volunteers recruited through specialised smoking cessation clinics in England, the United States and Denmark demonstrated the efficacy of the nicotine patch.^9,10,11 The Imperial Cancer Research Fund General Practice Research Group randomised 1686 heavy smokers (mean cigarette consumption 24 per day) to twelve weeks treatment with a 24-hour transdermal nicotine patch versus placebo.¹² Smoking cessation was confirmed in 163 patients (19.4%) using the nicotine patch and in 99 patients (11.7%) using the placebo patch (difference of 7.7%; p<0.0001). The authors concluded that nicotine patches are effective in the general practice setting. A one-year follow up of this trial confirmed that 9% of patients who received the nicotine patch continued to refrain from cigarettes as compared with 6.3% of patients who received placebo. The majority of patients receiving NRT in the general practice setting in Ireland received the patch preparation and in view of the advantages mentioned above together with the available clinical trial data this would appear appropriate.

The largest monthly increase in NRT prescriptions is noted for the month of January for the years 2002 and 2003. Prescriptions for nicorette patch and niquitin CQ patches increased over two-fold when compared with the preceding month of December. This may in part be related to patients new years resolution and their determination to give up smoking. However the number of patients receiving therapy falls sharply between the months of February to June. A similar though less marked trend is seen for prescribing in the nicotinell patch and to a lesser extent nicorette gum. The prevalence of cigarette smoking in Ireland is highest in the 18-34 year age group and lowest in those age 55 years or over. Our data indicates that the prescribing of NRT is greatest among the 25-54 year age group with peak prescribing between the ages of 35-44 years. A higher percentage of patients receiving treatment were female. This age and gender distribution of therapy could be considered a marker of appropriate prescribing. Another indicator of appropriate prescribing relates to the dosage of nicotine replacement therapy prescribed. Our study demonstrates that the majority of patients were commenced on the higher doses of NRT. This was not the case for nicotine chewing gum.

The National Institute for Clinical Excellence (NICE) has issued recommendations in relation to the duration of smoking cessation therapy in March 2002 (Table 3).¹³ It is seen that the duration of therapy for patients prescribed nicotine replacement therapy under the GMS scheme in Ireland is in keeping with NICE guidance.

Published work indicates that smoking cessation programmes, particularly those that rely on counselling with or without nicotine supplements, are highly cost effective in many settings.^14-17 Stapleton et al., conducted a specific analysis of the cost effectiveness of transdermal nicotine patches for smoking cessation in general practice.¹⁴ The analysis demonstrated that if general practitioners were to prescribe transdermal nicotine patches on the NHS for up to twelve weeks the incremental cost per life year saved would be 398stg per person for patients younger than 35 years, 345stg for those aged 35-44 years, 432stg for those aged 45-54 years and 785stg for those aged between 55-65 years. The study indicates that nicotine replacement therapy is most cost effective when used to treat smokers between the ages of 35-44 years. The treatment is less cost effective for older patients because they stand to gain fewer life years by stopping. However it should be emphasised that interventions resulting in a cost per life year saved of less than 20,000 would be considered highly cost effective. These findings are consistent with results from a US meta analysis of 13 clinical studies.¹⁵

In conclusion, there has been a significant uptake of NRT since its introduction to the GMS scheme in April 2001. Nicotine patch therapy accounts for 82.8% of all NRT dispensed in 2002. Prescribing trends are in keeping with current NICE guidance suggesting that the NRT expenditure of 2,709,954 in 2002 should provide value for money.

Correspondence: Michael Barry - Director, National Centre for Pharmacoeconomics,
St. Jamess Hospital, Dublin 8, Ireland

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