Efficacy of bupropion in the indigenous Maori population in New Zealand
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《胸》
1 P3 Research, Wellington, New Zealand
2 Wellington School of Medicine and Health Sciences, Wellington, New Zealand
3 Medical Research Institute of New Zealand, Wellington, New Zealand and University of Southampton, Southampton, UK
Correspondence to:
Dr S Holt
P3 Research, Bowen Hospital, Churchill Drive, Crofton Downs, Wellington, New Zealand; shaun@p3research.co.nz
Received 17 June 2004
Accepted for publication 3 October 2004
ABSTRACT
Background: Smoking rates are high in indigenous populations and contribute to their poor health. In New Zealand the indigenous Maori population has a high rate of smoking, with around 50% of adults being smokers compared with 20% of the adult European population. A study was undertaken to determine whether bupropion is effective in the treatment of smoking cessation in the indigenous Maori population in New Zealand.
Methods: A randomised, placebo controlled, double blind, parallel group study was performed in 134 Maori smokers aged 16–70 years who smoked more than 10 cigarettes per day. The main outcome measures were continued abstinence from smoking at 3 and 12 months.
Results: At each time point continued abstinence was better for the subjects allocated to bupropion, with a risk ratio for abstinence over all time points of 2.44 (95% CI 1.22 to 4.88). The rates of continued abstinence in the bupropion and placebo groups at 3 months were 44.3% and 17.4%, respectively, with a risk ratio of 2.54 (95% CI 1.30 to 5.00). The corresponding figures at 12 months were 21.6% and 10.9%, respectively, with a risk ratio of 1.99 (95% CI 0.79 to 5.00).
Conclusion: Bupropion is an effective treatment for smoking cessation in the indigenous Maori population in New Zealand.
Keywords: smoking cessation; bupropion; Maori
Smoking is a major public health issue worldwide and is a risk factor for many diseases, particularly lung cancer, chronic obstructive airways disease, coronary heart disease and cerebrovascular disease. Smoking tobacco is the leading cause of preventable death in the world, causing more than 4 million deaths per year.1 It has been estimated that smoking will kill 10 million people per year worldwide by the year 2025.2
The World Health Organization (WHO) launched the Decade of the World’s Indigenous Peoples initiative in 1994. There are around 5000 indigenous groups worldwide, in every continent, with a total population of about 200 million or 4% of the world population.3 Indigenous populations have different patterns of health, often with an unacceptably poorer health status than the non-indigenous population.4 For example, the difference in life expectancy between the indigenous population and the non-indigenous population has been found to be 4–21 years in several countries.4 Proposed reasons for these disparities include genetic vulnerability, socioeconomic disadvantage, and political oppression.5 A large proportion of the chronic diseases which contribute to the difference in life expectancy is preventable.
Smoking rates tend to be high in indigenous populations and contribute significantly to their burden of poor health. For example, in Australia 56% of indigenous men and 48% of women smoke compared with 27% and 20% of the whole population.6 In New Zealand 40–50% of Maori adolescents and adults are smokers compared with around 20% of the European population.7,8 One study has estimated that 31% of deaths among the Maori population in the period 1989–1993 were due to smoking.9
Despite many smokers wanting to quit, only 2–6% manage to stop smoking each year.10,11 Smoking has been shown not to be simply a habit but is a complex physiological addiction. Smoking cessation techniques are primarily behavioural (such as counselling) and/or pharmacological. Until recently pharmacological treatments were based on delivery of nicotine via a patch, gum, inhaler, or nasal spray.12,13 However, bupropion (Zyban) is a pharmacological treatment for smoking cessation which is available in tablet form and does not deliver nicotine.13–17 Bupropion, which acts on dopaminergic pathways, was originally used as an antidepressant but it was discovered in initial clinical studies that smokers were able to quit smoking after taking bupropion for depression.18 Studies have since demonstrated its efficacy and safety resulting in a near doubling of the smoking cessation rate,14–17 which is higher than that due to nicotine replacement therapy.19 However, no studies have assessed the efficacy and safety of bupropion for smoking cessation in an indigenous population. The aim of this study was to determine the effectiveness of bupropion for smoking cessation in Maori, the indigenous population in New Zealand.
METHODS
Design
A randomised, placebo controlled, double blind, parallel group, single centre study was undertaken in the Wellington and Kapiti regions in New Zealand, comparing the smoking cessation rate achieved with a 7 week course of bupropion and counselling with that achieved with placebo and counselling. Participants were followed up for 12 months after start of treatment.
Participants
The study participants were self-recruited from advertising in local media and actively recruited from Maori health networks. Regular meetings were held during which the details of the study were presented, including the inclusion and exclusion criteria. Suitable participants were then invited to attend a screening visit. The inclusion criteria were: self-identified as Maori; 16–70 years of age; smoking 10 cigarettes per day on average over the previous year; wanting to stop smoking; women of child bearing potential with a negative pregnancy test at visit 1 and a reliable method of contraception. The exclusion criteria were: history of epilepsy, febrile convulsions, CNS tumour, head injury, cerebrovascular disease; anorexia or bulimia; significant cardiovascular disease including unstable angina, a myocardial infarction in the previous 3 months, arrhythmias, uncontrolled hypertension; other severe illness such as renal, hepatic or neurological disease; pregnant or lactating; history of alcohol or drug abuse; unwilling to stop smoking marijuana during the trial. The flow of subjects through the study is shown in fig 1.
Table 2 Analysis of non-smoking rates by measurement time without adjustment for repeated measurements
For the model based approach with a break point in the abstinence-time slope at 26 weeks, the risk ratio for abstinence favoured the bupropion group (2.44 (95% CI 1.22 to 4.88)). Figure 2 shows the fitted and raw probabilities for the repeated measures model.(S Holt1, C Timu-Parata1, )
2 Wellington School of Medicine and Health Sciences, Wellington, New Zealand
3 Medical Research Institute of New Zealand, Wellington, New Zealand and University of Southampton, Southampton, UK
Correspondence to:
Dr S Holt
P3 Research, Bowen Hospital, Churchill Drive, Crofton Downs, Wellington, New Zealand; shaun@p3research.co.nz
Received 17 June 2004
Accepted for publication 3 October 2004
ABSTRACT
Background: Smoking rates are high in indigenous populations and contribute to their poor health. In New Zealand the indigenous Maori population has a high rate of smoking, with around 50% of adults being smokers compared with 20% of the adult European population. A study was undertaken to determine whether bupropion is effective in the treatment of smoking cessation in the indigenous Maori population in New Zealand.
Methods: A randomised, placebo controlled, double blind, parallel group study was performed in 134 Maori smokers aged 16–70 years who smoked more than 10 cigarettes per day. The main outcome measures were continued abstinence from smoking at 3 and 12 months.
Results: At each time point continued abstinence was better for the subjects allocated to bupropion, with a risk ratio for abstinence over all time points of 2.44 (95% CI 1.22 to 4.88). The rates of continued abstinence in the bupropion and placebo groups at 3 months were 44.3% and 17.4%, respectively, with a risk ratio of 2.54 (95% CI 1.30 to 5.00). The corresponding figures at 12 months were 21.6% and 10.9%, respectively, with a risk ratio of 1.99 (95% CI 0.79 to 5.00).
Conclusion: Bupropion is an effective treatment for smoking cessation in the indigenous Maori population in New Zealand.
Keywords: smoking cessation; bupropion; Maori
Smoking is a major public health issue worldwide and is a risk factor for many diseases, particularly lung cancer, chronic obstructive airways disease, coronary heart disease and cerebrovascular disease. Smoking tobacco is the leading cause of preventable death in the world, causing more than 4 million deaths per year.1 It has been estimated that smoking will kill 10 million people per year worldwide by the year 2025.2
The World Health Organization (WHO) launched the Decade of the World’s Indigenous Peoples initiative in 1994. There are around 5000 indigenous groups worldwide, in every continent, with a total population of about 200 million or 4% of the world population.3 Indigenous populations have different patterns of health, often with an unacceptably poorer health status than the non-indigenous population.4 For example, the difference in life expectancy between the indigenous population and the non-indigenous population has been found to be 4–21 years in several countries.4 Proposed reasons for these disparities include genetic vulnerability, socioeconomic disadvantage, and political oppression.5 A large proportion of the chronic diseases which contribute to the difference in life expectancy is preventable.
Smoking rates tend to be high in indigenous populations and contribute significantly to their burden of poor health. For example, in Australia 56% of indigenous men and 48% of women smoke compared with 27% and 20% of the whole population.6 In New Zealand 40–50% of Maori adolescents and adults are smokers compared with around 20% of the European population.7,8 One study has estimated that 31% of deaths among the Maori population in the period 1989–1993 were due to smoking.9
Despite many smokers wanting to quit, only 2–6% manage to stop smoking each year.10,11 Smoking has been shown not to be simply a habit but is a complex physiological addiction. Smoking cessation techniques are primarily behavioural (such as counselling) and/or pharmacological. Until recently pharmacological treatments were based on delivery of nicotine via a patch, gum, inhaler, or nasal spray.12,13 However, bupropion (Zyban) is a pharmacological treatment for smoking cessation which is available in tablet form and does not deliver nicotine.13–17 Bupropion, which acts on dopaminergic pathways, was originally used as an antidepressant but it was discovered in initial clinical studies that smokers were able to quit smoking after taking bupropion for depression.18 Studies have since demonstrated its efficacy and safety resulting in a near doubling of the smoking cessation rate,14–17 which is higher than that due to nicotine replacement therapy.19 However, no studies have assessed the efficacy and safety of bupropion for smoking cessation in an indigenous population. The aim of this study was to determine the effectiveness of bupropion for smoking cessation in Maori, the indigenous population in New Zealand.
METHODS
Design
A randomised, placebo controlled, double blind, parallel group, single centre study was undertaken in the Wellington and Kapiti regions in New Zealand, comparing the smoking cessation rate achieved with a 7 week course of bupropion and counselling with that achieved with placebo and counselling. Participants were followed up for 12 months after start of treatment.
Participants
The study participants were self-recruited from advertising in local media and actively recruited from Maori health networks. Regular meetings were held during which the details of the study were presented, including the inclusion and exclusion criteria. Suitable participants were then invited to attend a screening visit. The inclusion criteria were: self-identified as Maori; 16–70 years of age; smoking 10 cigarettes per day on average over the previous year; wanting to stop smoking; women of child bearing potential with a negative pregnancy test at visit 1 and a reliable method of contraception. The exclusion criteria were: history of epilepsy, febrile convulsions, CNS tumour, head injury, cerebrovascular disease; anorexia or bulimia; significant cardiovascular disease including unstable angina, a myocardial infarction in the previous 3 months, arrhythmias, uncontrolled hypertension; other severe illness such as renal, hepatic or neurological disease; pregnant or lactating; history of alcohol or drug abuse; unwilling to stop smoking marijuana during the trial. The flow of subjects through the study is shown in fig 1.
Table 2 Analysis of non-smoking rates by measurement time without adjustment for repeated measurements
For the model based approach with a break point in the abstinence-time slope at 26 weeks, the risk ratio for abstinence favoured the bupropion group (2.44 (95% CI 1.22 to 4.88)). Figure 2 shows the fitted and raw probabilities for the repeated measures model.(S Holt1, C Timu-Parata1, )