1 Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences
2 Institute for Global Tobacco Control, Johns Hopkins Bloomberg School of Public Health
3 Johns Hopkins Bloomberg School of Public Health
Correspondence: Prof. J Samet, Johns Hopkins Bloomberg School of Public Health, Department of Epidemiology, 615N Wolfe St, Baltimore, MD21205, USA. E-mail: jsamet{at}jhsph.edu
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Abstract |
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Methods A survey of smoking behaviour and smoking-related knowledge and attitudes was administered to 24 000 youths (students and non-students of middle school age) in 24 disease surveillance points in China, selected to include equal numbers of urban and rural children.
Results The prevalence rates of experimenting were 47.8% for boys and 12.8% for girls. The prevalence of regular smoking among non-students was higher (8.3%) compared with students (5.2%). The strongest predictor of regular smoking was peer influence with 44% reporting that they obtained their first cigarette from peers. The majority of youths were aware that smoking was a cause of several diseases and addictive; however, non-students were less aware than students.
Conclusions The evidence highlights the need for tobacco control interventions aimed at youths in China including non-student youths. For males, prevention programmes should extend into young adulthood.
Accepted 7 April 2004
China now produces and consumes about 42% of all cigarettes in the world.1 Studies of tobacco-related mortality in China have shown that even though China is still in the early phase of its epidemic of tobacco-caused deaths, tobacco smoking already accounts for approximately 800 000 deaths annually.2 Further, evidence suggests that tobacco use is rising and recent surveys show inadequate knowledge of the health consequences of active and passive smoking and little interest in quitting among the 320 million current smokers.3 Any comprehensive tobacco control plan in China will need to address this enormous number of committed smokers and also reduce rates of smoking initiation among the nation's youth, who may be taking up smoking at rising rates and earlier ages.3
To collect data that will inform the development of tobacco control initiatives directed at youth, we conducted a survey of 24 000 children ages 1120 years in 24 different regions, selected to include equal numbers of urban and rural children. There have been several previous studies on smoking prevalence and smoking-related knowledge, attitudes, and behaviours among adolescents in China, including the Global Youth Tobacco Survey.46 These studies were limited to a few regions and had small sample sizes, except for the Global Youth Tobacco Survey, which included over 10 000 children, 1315 years of age, from four cities. The present survey was carried out in 1998 to gain a more comprehensive picture of smoking prevalence; knowledge and attitudes relating to smoking; the health effects of smoking and tobacco control programmes; and tobacco-related behaviours among youth in and out of school.
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Study population and methods |
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Sampling planning
The target sample size, determined by resource availability, was 1000 children in each of the 24 areas. Sampling was school-based with stratification by type of school (regular or vocational/technical), and with over-sampling among non-students aged 1318 years in the rural areas. Within each area, a two-stage stratified cluster sample of schools was taken. The schools were divided by type and then sampled with a probability of selection based on school enrolment in each type. In the second stage, predetermined numbers of children based on total school size were randomly sampled from a student list. Classes were not used as the sampling unit to avoid peer pressure to participate. In the rural areas, adolescents were sampled on a convenience basis in the villages to reflect the proportion of children in each category that had left school.
Questionnaire
The questionnaire covered five broad categories: (1) demographics and personal information; (2) knowledge and attitudes: exposure to and attitudes towards tobacco control programmes/messages, knowledge of health effects of smoking, and attitudes towards tobacco use; (3) tobacco useby the participant and by others in his/her home and community; (4) cessation; and (5) passive smoke exposure. The questionnaire was written in Chinese, translated into English, then translated back into Chinese to ensure that questions were understood identically by co-researchers from the Chinese Academy of Medical Sciences and the Johns Hopkins University. A pilot study was carried out in 10 schools in two of the 24 selected geographical areas (Sijiazhuang of Hebei province and Zhengyi of Guizhou province).
Data collection and quality control
Supervisors in the 24 areas were centrally trained to ensure that the survey was carried out according to the protocol and that operative procedures were identical across the 24 areas. All questionnaires were sent to Beijing, and entered by trained data-entry personnel. Quality was assured by using double data entry procedures and a system for detecting data entry errors. Any potential errors were verified against the original questionnaire.
Data analysis
Initially we explored patterns of smoking initiation by sex, age, region, and student status. Knowledge and attitudes were also described in relation to these same factors. We next developed multiple logistic regression models to characterize predictors of experimenting (ever taking a puff) or of becoming a smoker (ever smoking weekly for 3 months). The source for the first cigarette smoked, costs of using cigarettes, the knowledge of risks to health and nicotine addiction, and attitudes towards smoking were described.
For the logistic regression analyses, variables were grouped into categories of environmental factors and attitudes and beliefs, and results were presented in two corresponding tables. The non-students were excluded from these models because of ambiguity in interpreting these responses to items about schools. Data for males and females were analysed separately in both models because of substantial differences in the number of experimenters and smokers by gender, as few females reported smoking. All models were also adjusted for age because age was a strong predictor of being an experimenter or a smoker. In the first set of analyses, personal and environmental factors were modelled, which included region (urban/rural), student status, school performance, smoking status of parents, friends, classmates, teachers and doctors, and socioeconomic status as defined by parents' occupations and levels of education.
In a second set of analyses, attitudes and beliefs were modelled while adjusting for personal and environmental factors. Variables in the attitudes and beliefs model included perception of risk associated with smoking and whether respondents would smoke knowing these risks. Also included in the model were attitudes about smoking based on impressions of seeing doctors, teachers, and movie stars smoke. All analyses were carried out using SAS.8
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Study results |
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Discussion |
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The influence of peers found in this study is similar to research in China and elsewhere. In their recent synthesis, the US group of Jacobsson and colleagues11 concluded that peer influence was the strongest predictor of smoking initiation. Findings of other studies in China have also found strong effects of peer group smoking. Three reports cover elementary school students,13 middle school students,5 and high school students.14 For elementary school students, having at least one friend who smoked was associated with a more than sevenfold risk of occasional smoking.13 For high school students, peer smoking had a strong effect on risk for daily and weekly smoking (OR = 10.5, 95% CI: 8.0, 13.8 for boys and OR = 5.4, 95% CI: 3.1, 9.2 for girls).14 Peer smoking was also associated with smoking status in middle school children in Beijing, but a measure of association was not provided.5 In a survey of Honan province children, peer smoking had the strongest effect on risk for smoking (OR = 2.6, 95% CI: 2.0, 3.5). The associations found in this study are similar to these previous reports (Table 5). Interpretation as to the causality of the association needs to be guarded because of the cross-sectional nature of the data.
The prevalence of smoking among non-students was higher (8.3%) than in students (5.2%). These statistics, along with the evidence that non-students are less aware of the health risks associated with smoking due to their lower educational level, highlight the need to develop tobacco control interventions in China aimed at non-student youth. Importantly, the proportion of youth aged 1519 years who have already discontinued their studies is considerable, about 40%.9
We found that patterns of tobacco use among adolescents, for the most part, still adhere to traditional Chinese cultural patterns apparent among adults.3 For example, smoking is still regarded as a male behaviour and an adult activity, resulting in significantly lower smoking rates among girls and an older average age of initiation than in Western industrial countries. However, Figure 1 shows that experimentation does begin at young ages among boys and if China follows trends in other countries, the age of regular smoking might drop and experimentation might rise in girls. Surveillance of youth smoking for these possible warning signs is needed. In the 1996 national survey, a sharp rise in the prevalence of smoking was observed, comparing people aged 1519 years and 2024 years.3 The current survey provides consistent information, suggesting that prevention efforts should focus on the young adult years as well as adolescence.
A noteworthy difference in this study from the 1996 adult study3 is that there were no significant differences between never smokers and experimenters or between never smokers and smokers in relation to knowledge concerning the harmful health effects of smoking. Additionally, the adolescents in this survey had a greater awareness of health risks of smoking than did adults surveyed in 1996. This difference may illustrate the effectiveness of health education classes focusing on the health hazards associated with tobacco in school, but the results also suggest that these classes have not been effective at curbing adolescent access to and experimentation with tobacco. A comprehensive tobacco control programme that goes beyond the communication of health dangers is needed to curb adolescent smoking.
This study has a number of potential limitations. Problems with recall may have biased findings on age of first experimentation. The higher prevalence of smokers and lower prevalence of experimenters among non-students compared with students may be explained by the older age distribution of non-students who did not become smokers and their greater inability to remember whether or not they ever tried a puff of a cigarette. For feasibility, the non-students were selected by a convenience approach and the representation of the responses by survey participants is uncertain. Additionally, we did not attempt to validate self-reported smoking against biomarkers such as cotinine.
Strong tobacco control strategies, especially those focused on adolescents and young adults, are urgently needed in China. Our findings indicate that protection of adolescents from their first smoking experience is a key step in which family, doctors, and teachers can make a difference. Parents, teachers and doctors should be aware of adolescents' behaviours, understand the peer group's influence and recognize risk factors for smoking. A comprehensive programme against tobacco use, which includes the community and school, also needs to be developed and implemented. Effective components of this intervention should encourage communities to modify their social norms and enforce regulation. Many of the components are key elements in a proposal made by national experts at a conference on tobacco control and health in 2000.15 However, a national tobacco control plan is not yet final.
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References |
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