Secular trends in adult male smoking from 1992 to 2006 in South Korea: Age-specific changes with evolving tobacco-control policies

Public Health 123 (2009) 657–664

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Original Research

Secular trends in adult male smoking from 1992 to 2006 in South Korea: Age-specific changes with evolving tobacco-control policies E.J. Park a, H.K. Koh b, J.W. Kwon c, M.K. Suh d, H. Kim a, S.I. Cho a, * a

School of Public Health and Institute of Health and Environment, Seoul National University, Yeongun-dong, Jongno-gu, Seoul, 110-460, Republic of Korea Division of Public Health Practice, Harvard School of Public Health, Boston, MA, USA c School of Pharmacy, Rutgers University, Piscataway, NJ, USA d Korea Institute for Health and Social Affairs, Seoul, Republic of Korea b

a r t i c l e i n f o

s u m m a r y

Article history: Received 27 February 2009 Received in revised form 22 August 2009 Accepted 15 September 2009 Available online 4 November 2009

Objectives: For years, South Korea has had one of the highest levels of tobacco use among males in the world, but a steady decline has been observed recently. This study examined how the smoking behaviour of male adults changed with age after the implementation of national tobacco control policies in 1995. Study design: Repeated cross-sectional study using a national survey. Methods: Data were obtained from the 1992, 1995, 1999, 2003 and 2006 results of a repeated crosssectional survey, the Social Statistics Survey. The smoking status of adult men was compared before (1992 and 1995 surveys) and after (1999, 2003 and 2006 surveys) the implementation of governmentdirected tobacco control policies using graphical methods and logistic regression analysis. Results: After the implementation of tobacco control policies, the percentage of current male smokers decreased while the percentage of former smokers increased markedly. Smoking prevalence among older men (aged 50 years or more) reduced initially, and this decline was more pronounced after the tobacco control policies were implemented. Smoking prevalence in younger men (aged 30–49 years) declined in 2003 when more comprehensive tobacco control policies were implemented. Conclusions: This study suggests that comprehensive tobacco control policies in South Korea reduced smoking prevalence among males, initially among older men and later among both older men and younger men. Ó 2009 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Keywords: Cigarette smoking Smoking prevalence Tobacco control policies Age group

Introduction Whereas developed countries in the west such as the USA, Canada and Western Europe have experienced a slow but steady decrease in male smoking rates over the last 30 years,1–5 the prevalence of smoking in men aged 20 years in South Korea declined abruptly from 73.2% in 1992 to 52.2% in 2006.6 This remarkable speed in the reduction of smoking prevalence appears to be unprecedented, especially for a country that has long had one of the highest male smoking rates in the world. For example, in the USA, it took 26 years for the percentage of male adult smokers to decline steadily from 51.9% in 1965 to 28.1% in 1991.7 In Japan, it took over 20 years for the percentage of male daily smokers (aged 15 years and older) to decrease from 73.1% in 1979 to 52.0% in 2001.8 In Europe, it took more than 20 years for the reduction of male smoking prevalence from 70% to 50% in Denmark and the Netherlands.2 * Corresponding author. Tel.: þ82 2 880 2583; fax: þ82 2 882 8632. E-mail address: [email protected] (S.I. Cho).

What happened in South Korea during that period? Although non-governmental organizations had previously conducted some anti-smoking activities, in 1995, the Korean Government launched tobacco control policies for the whole population. In addition to some pre-existing policies such as restrictions on cigarette advertising and health warnings on packages, the Government passed the National Health Promotion Act in 1995, which strengthened package warnings and initiated the designation of non-smoking areas. Such government-driven tobacco control policies expanded each year. Of note, in 2004, the price rose by 44 cents per pack, which was equivalent to a 33% increase for popular cigarette products. As a result, the proportion of the price that was earmarked for public health funding increased from 10% to 18% per pack. In addition, television anti-smoking advertising was started in 2000, and smoking cessation clinics at public health centres commenced in 2005. The Korean Government signed the World Health Organization (WHO) Framework Convention on Tobacco Control in 2003 and ratified it in 2005. The budget for national smoking cessation services also increased continuously (Table 1).9

0033-3506/$ – see front matter Ó 2009 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.puhe.2009.09.007

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Table 1 Budget (in million US dollars) of national smoking cessation services of the Korean Government, 1998–2005.a 1998 1999 2000 2001 2002 2003 2004 2005 Anti-smoking education 0.30 0.28 0.49 Anti-smoking advertising 0.06 0.20 0.89 1.95 Smoking prevalence survey 0.04 0.04 0.07 Health examination 0.22 0.27 for smokers 0.26 0.16 0.53 Anti-smoking activities by public health centresb Smoking cessation clinics at public health centresc Total

2.19 3.03 0.07 0.28

1.99 2.65 0.02 0.34

2.12 3.87 0.02 0.35

4.42 7.62 0.06

0.54 0.57 0.55 0.09 13.25

0.32 0.54 1.59 3.31 6.11 5.57 7.00 25.35

a

Modified from Reference 9. Budget was converted to US dollars using the US$ exchange rate for each year in OECD Health Data 2008. b Included smoking cessation counselling and education for community residents, anti-smoking campaign, and monitoring of implementation of tobacco control policies. c Smoking cessation clinics at public health centres provided smoking cessation counselling and nicotine replacement therapy. Smoking cessation clinics were operated at 10 public health centres as test programmes in 2004 and at all public health centres in 2005.

Korean tobacco trends must be analysed in the context of these national and global efforts.10 However, compared with Western countries, far fewer studies have examined the link between trends in smoking prevalence and tobacco control policies in Asia, which has carried a disproportionately high burden of tobacco dependence among the male population. Successive national representative data are required to examine the trends in smoking status over sufficient periods of time. Two surveys have repeatedly examined smoking prevalence in South Korea: the Social Statistics Survey (SSS) and the Korea National Health and Nutrition Examination Survey (KNHANES). The SSS includes approximately 30,000 men each year, using consistent survey methods, whereas the KNHANES covers approximately 4000 male respondents; thus, the SSS can provide reliable smoking prevalence data according to age group. Moreover, the time periods covered by the SSS include surveys before and after implementation of tobacco control policies by the Government, with data collected by interviews of non-institutional populations in a manner similar to the US National Health Interview Survey. Despite the fact that age, as well as other sociodemographic factors,11–16 is among the most important variables as a determinant of smoking behaviour17–19 and as a modifier of policy effects,20–22 surprisingly few studies have focused on age-specific trends in smoking prevalence. It has previously been reported that older people are more responsive to price increases than those in their 30s,21 and younger people who are exposed to tobacco control policies in earlier life are less likely to smoke.23 It would be interesting to examine the age-specific changes in smoking prevalence, considering the recent extensive tobacco control efforts in South Korea. The SSS offers the opportunity to gather information about detailed age-specific trends, as well as insights about possible links to interventions. These include the development and promotion of more effective anti-tobacco policies, such as raising the price of cigarettes. Also, the detailed analyses of the SSS can avoid the problems of studies that monitor the impact of tobacco control policies using endpoints such as overall smoking prevalence or tobacco consumption, which may regard large changes in subpopulations as changes in the whole population. The conceptual framework for this study is presented in Fig. 1. As the SSS was conducted in the middle of the year, it was postulated that newly introduced or intensified tobacco control policies from preceding years would have influenced smoking prevalence in the

survey year. For example, changes in anti-smoking policies during 1999–2002 (anti-smoking advertising on television, listing of tar and nicotine contents on packages, and cigarette price increases) were assumed to have an effect on smoking prevalence in 2003.24,25 The secular trends in smoking prevalence were analysed using age–period analysis and the period effects that were related to changes in tobacco control policies were interpreted. Age effects refer to the influence of age on smoking prevalence, and period effects represent the change in smoking prevalence over time, which was shown in all age groups. Tobacco control policies for all age groups may cause period effects. The objective of this study was to assess the effect of tobacco control policies implemented since 1995 in South Korea, with a focus on the differential effects across age groups in men. Smoking status was compared before and after the implementation of tobacco control policies, and changes in smoking prevalence in various age groups were evaluated using graphical methods. Finally, the separate effects of age and period on smoking prevalence were estimated. Methods Data To compare smoking status before and after the implementation of tobacco control policies, the repeated cross-sectional survey data on smoking status from the 1992, 1995, 1999, 2003 and 2006 SSS were used. The SSS is a household-based survey that is conducted annually by South Korea’s National Statistical Office and provides nationally representative data. This survey is aimed at investigating the quality of life and current changes in society. The 1992 and 1995 data served as an inherent control because the survey was completed prior to the implementation of government-initiated tobacco control policies. The 1999, 2003 and 2006 survey data were collected with tobacco control policies in place. Smoking status, age, gender, marital status and educational attainment were either examined in person or provided by the individual. Details of the data set have been published previously.26,27 Study population As approximately 97% of smokers start to smoke before 30 years of age,28 the analysis focused on men aged 30 years to assess the age-specific trends in smoking prevalence over a historical period characterized by rapid smoking cessation. The numbers of subjects included in the analysis from the five surveys were as follows: 25,771 (1992); 26,084 (1995); 22,820 (1999); 24,838 (2003); and 24,425 (2006). Definitions of smoking status In the 1992, 1995 and 1999 surveys, smoking status was measured with the following three choices: currently smoke, have smoked in the past but do not smoke now, and never smoked. In the 2003 survey and the 2006 survey, individuals were asked a series of sequential questions. First, they were asked if they smoked currently, and respondents who answered that they did were defined as current smokers. Those who answered that they did not were asked if they had smoked in the past. The question of whether they had smoked at least 100 cigarettes in their lifetimes (the WHO definition of an ‘ever’ smoker) was not asked. Those who responded that they had smoked before but did not smoke now were regarded as past smokers, and those who had never smoked were classified as never smokers.

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Figure 1. Conceptual framework for study: smoking prevalence changes with evolving governmental tobacco control policies in South Korea.

The smoking prevalence in each age group was calculated as the weighted number of current smokers divided by the total number of respondents. To compare smoking prevalence for each year, smoking prevalence was standardized to the age distribution of the 1999 survey using a direct standardization method. Statistical methods Logistic regressions were fitted to examine the effects of age and period on smoking prevalence. The proportion of current smokers by year of survey and age group was used as the dependent variable. The independent variables included age, period, marital status and educational attainment. Age was assessed in years and stratified into 5-year categories (from 30–34 years up to 80–84 years). Age groups were excluded when they contained fewer than 100 subjects, and the age groups for 75–79 and 80–84 years were combined into one group because of the relatively small sample size. The survey years were used as the periods: 1992, 1995, 1999, 2003 and 2006. Marital status and educational attainment were included to control the effect of socioeconomic change by year; the number of men who were highly educated or not married increased from 1992 to 2006. Marital status was measured as the age- and period-specific percentage of unmarried men (single, widowed, separated or divorced), and educational attainment as the age- and period-specific percentage of college graduates.

Modelling was conducted hierarchically from an empty model without explanatory variables, followed by the addition of other variables such as age, period, marital status and educational attainment. The final model was defined as follows:

lnðp=1  pÞ ¼ a þ

X i

b1i agei þ

X

b2j periodj

j

þ b3 ð% unmarriedÞ þ b4 ð% college educationÞ where p refers to smoking prevalence, ln() refers to natural logarithm function, and i and j refer to indicators for age and period categories, respectively. Statistical analyses were performed using the logit transformation in the GENMOD procedure of SAS Version 9.1 (SAS Institute Inc., Cary, NC, USA). The goodness-of-fit of the models was assessed by deviance divided by degree of freedom, and the pscale option in the GENMOD procedure was used to correct for overdispersion in the binomial distribution. The statistical significance level was set at P  0.05. Results Fig. 2 shows the smoking status among adult men in 1992, 1995, 1999, 2003 and 2006. The percentage of current smokers was

660

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which suggests that the tobacco control policies implemented between 1999 and 2002 lowered smoking prevalence among younger men whose smoking rate had not decreased previously. Fig. 3 also shows that smoking prevalence among the older men declined continuously, starting from the earlier periods. Table 3 compares different models of smoking prevalence, starting with an empty model (Model 1) and then sequentially adding age (Model 2) and period (Model 3). Marital status and educational attainment were adjusted in Models 4 and 5. The probability of smoking decreased with advancing age, and the period effect became stronger over time in Model 3. Men aged 55 years were significantly less likely to smoke than those aged 30–34 years after adjusting for changes in marital status and educational attainment. The period effect was significant in 1999, 2003 and 2006 compared with 1992, with or without adjustment for the change in marital status or educational attainment. Table 4 presents the age and period effect in younger men aged 30–49 years and in older men aged 50 years. An increasing age effect was observed in both age groups. Among younger men, the period effect was only significant in 2003 and 2006 compared with 1992, and the negative period effect on smoking prevalence increased more from 1999 to 2003 than from 2003 to 2006, when comparing the coefficient of the period effect by year. Among older men, period effects were significant across all periods and increased continuously.

Figure 2. Changes in smoking status among men aged 30 years and older in South Korea, 1992–2006.

72.37% in 1992. After anti-smoking policies were implemented by the Korean Government in 1995, smoking prevalence decreased to 66.92% in 1999 and 52.43% in 2006. Age-standardized smoking prevalence was 71.71% in 1992, 66.92% in 1999 and 53.05% in 2006, using 1999 surveys as the standard population. On the other hand, the percentage of past smokers increased 2.26-fold in 1999 and 3.66-fold in 2006 compared with 1992. The percentage of never smokers changed slightly when compared with past smokers. Table 2 outlines survey years by age group. The change in smoking prevalence according to age and year of survey is presented in Fig. 3. Smoking prevalence decreased with advancing age during all five periods. The decline in smoking prevalence with advancing age became steeper over the whole period, indicating that the older age group showed a greater decline in smoking prevalence. In addition, a large decrease in prevalence across all ages occurred between 1999 and 2003. The right panel of Fig. 3 summarizes the trends for younger (30– 49 years old) and older (50–84 years old) age groups. Up to 1999, smoking prevalence decreased little in the younger age group, but decreased markedly in the older age group. In contrast, smoking prevalence in the younger age group declined markedly in 2003,

Discussion This study shows that a decrease in the number of current adult male smokers and an increase in the number of past smokers coincided with the implementation of government-initiated tobacco control policies. Smoking prevalence initially decreased among older men (aged 50 years), and this age-associated decline became greater the longer these policies were in effect. Smoking prevalence in younger men (30–49 years old) decreased in 2003. The combination of these two effects resulted in a remarkable reduction in smoking prevalence during a short period in South Korea. In this study, the smoking prevalence of Korean men aged 30 years decreased from 72.37% in 1992 to 52.43% in 2006. This decline has been documented in previous studies. Jee et al. reported a Korean male smoking prevalence of 70.2% in 1994 using telephone surveys.29 Smoking prevalence in those aged 25–74 years in 1999 and 2003 was 68.6% and 57.0%, respectively.30 A study by Cho et al., which used longitudinal data from 1990 to 1998, showed a similar decline in smoking prevalence among male civil servants.31

Table 2 Number of subjects and smoking prevalence in each age group by survey year. Age group (years)

1992 n

30–34 35–39 40–44 45–49 50–54 55–59 60–64 65–69 70–74 75–84 Total

1995 Smoking prevalence (%)

n

1999 Smoking prevalence (%)

n

2003 Smoking prevalence (%)

n

2006 Smoking prevalence (%)

n

Smoking prevalence (%)

5220 4395 3501 3037 3032 2519 1621 1128 748 570

79.02 75.46 71.83 70.29 69.72 69.41 68.18 66.56 63.80 60.16

4850 4778 3674 3167 2755 2405 1761 1184 859 651

78.77 76.22 74.82 70.40 69.54 66.80 66.06 64.21 55.81 54.78

3516 3988 3788 2751 2320 2015 1853 1198 729 662

76.29 74.11 71.45 68.46 62.30 59.34 56.51 53.08 49.12 45.00

3717 3760 4191 3515 2530 2119 1796 1511 940 759

65.39 63.48 60.33 56.13 52.60 48.20 43.33 40.69 37.82 34.57

3037 3450 3665 3778 2910 2193 1733 1605 1181 873

62.01 62.01 58.66 55.16 50.05 45.05 40.60 37.57 31.70 26.03

25,771

72.37

26,084

72.03

22,820

66.92

24,838

55.61

24,425

52.43

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661

Figure 3. Age-specific smoking prevalence among men aged 30 years and older in South Korea, 1992–2006.

The present study found that smoking prevalence among older men decreased in each survey year, whereas smoking prevalence among younger men decreased in 2003. The sequential reduction of smoking prevalence in the older age group followed by the reduction in the younger age group has rarely been reported in Western studies. Smoking prevalence decreased in all age groups

with the Finnish Tobacco Control Act.32 The reduction in smoking prevalence was greater among young adults than among older people in the USA from 1965 to 1991.7 This modification of the effect of tobacco control policies by age requires further attention. It may reflect the selective effect of tobacco control policies according to age. Smoking prevalence

Table 3 Logistic regression results of age and period on smoking prevalence among men aged 30–84 years in South Korea, 1992–2006. Model 1

Model 2

Model 3

Model 4

Model 5

Parameter estimate

P-value

Parameter estimate

P-value

Parameter estimate

P-value

Parameter estimate

P-value

Parameter estimate

P-value

Intercept Age (years) 30–34 35–39 40–44 45–49 50–54 55–59 60–64 65–69 70–74 75–84 Period 1992 1995 1999 2003 2006 % Unmarried % College education

0.56

<0.001

0.98

<0.001

1.35

<0.001

1.02

<0.001

0.88

<0.001

0.00 0.11 0.26 0.43 0.55 0.64 0.81 0.97 1.16 1.31

0.61 0.21 0.04 0.02 0.01 0.001 0.001 0.001 0.001

0.00 0.10 0.23 0.38 0.53 0.66 0.79 0.91 1.11 1.27

0.04 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001

0.00 0.11 0.05 0.09 0.23 0.35 0.48 0.63 0.87 1.17

0.17 0.63 0.35 0.03 0.001 <0.001 <0.001 <0.001 <0.001

0.00 0.06 0.03 0.06 0.15 0.25 0.37 0.48 0.69 0.89

0.48 0.78 0.55 0.16 0.03 0.002 <0.001 <0.001 <0.001

0.00 0.02 0.24 0.73 0.84

0.71 <0.001 <0.001 <0.001

0.00 0.04 0.30 0.82 0.97 0.01

0.35 <0.001 <0.001 <0.001 0.001

0.00 0.06 0.33 0.89 1.04 0.007 0.009

0.17 <0.001 <0.001 <0.001 0.20 0.05

Deviance/df

165.08

103.25

6.07

4.77

4.41

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Table 4 Logistic regression results of age and period on smoking prevalence in younger men (30–49 years old) and older men (50–84 years old) in South Korea, 1992–2006. Model 1 Parameter estimate Younger men (30–49 years old) Intercept 0.80 Age (years) 30–34 35–39 40–44 45–49 Period 1992 1995 1999 2003 2006 % Unmarried % College education Older men (50–84 years old) Intercept 0.20 Age (years) 50–54 55–59 60–64 65–69 70–74 75–84 Period 1992 1995 1999 2003 2006 % Unmarried % College education

Model 2 P-value

<0.001

Parameter estimate 0.98 0.00 0.11 0.26 0.43

0.03

Model 3 P-value

<0.001

0.63 0.24 0.06

Parameter estimate

Model 4 P-value

Parameter estimate

Model 5 P-value

Parameter estimate

P-value

1.25

<0.001

1.47

<0.001

1.39

<0.001

0.00 0.10 0.23 0.39

<0.001 <0.001 <0.001

0.00 0.26 0.44 0.61

<0.001 <0.001 <0.001

0.00 0.26 0.42 0.57

<0.001 <0.001 <0.001

0.00 0.04 0.09 0.60 0.68

0.20 0.01 <0.001 <0.001

0.00 0.07 0.02 0.51 0.54 0.01

0.004 0.45 <0.001 <0.001 0.001

0.00 0.06 0.04 0.56 0.59 0.01 0.003

0.03 0.25 <0.001 <0.001 <0.001 0.37

0.44

0.01

0.97

<0.001

0.82

<0.001

0.57

<0.001

0.00 0.09 0.27 0.42 0.62 0.76

0.70 0.30 0.14 0.06 0.04

0.00 0.14 0.26 0.37 0.58 0.73

0.001 <0.001 <0.001 <0.001 <0.001

0.00 0.12 0.23 0.42 0.70 1.16

<0.001 <0.001 <0.001 <0.001 <0.001

0.00 0.06 0.16 0.31 0.56 0.99

0.13 <0.001 <0.001 <0.001 <0.001

0.00 0.10 0.46 0.92 1.07

0.04 <0.001 <0.001 <0.001

0.00 0.11 0.46 0.96 1.14 0.03

0.001 <0.001 <0.001 <0.001 <0.001

0.00 0.14 0.55 1.07 1.25 0.03 0.02

<0.001 <0.001 <0.001 <0.001 <0.001 0.02

among men aged 50 years was reduced before the Government implemented tobacco control policies in 1995, as well as in the early stages of government-driven tobacco control policies. Government-directed tobacco control policies started in 1995, but knowledge about the harmful effects of smoking had been disseminated to the public through anti-smoking campaigns by non-governmental organizations and warnings on tobacco packages prior to that time. In a series of smoking surveys of Korean high school students, 73.0% of male students responded in 1991 that smoking affected health negatively, and this response increased to 84.7% in 1999.33 One reason for the decline in smoking prevalence seen initially in older men may be health concerns or illness,19,34 which only leads to smoking cessation when the health effects of smoking are well known. In the 1998 national survey, 58.5% of Korean male past smokers cited ill health as a reason to quit smoking, and this response increased with advanced age.35 Knowledge about the severity of effects of smoking on health was related to the intention to participate in smoking cessation programmes in the study by Son et al. using the health belief model.36,37 Elderly people with health problems may be advised by doctors to stop smoking. In a study of doctors, 84.7% responded that they advised patients about smoking cessation.38 Older men were more likely than younger men to be advised by a doctor to quit smoking.39 As a result of the increase in smoking cessation among older people, social pressure is directed at smoking cessation for older individuals, in contrast to the pressure to begin smoking in adolescence.40 The South Korean population has experienced a dramatic intensification of tobacco control policies over a period of 10 years, which is a much shorter time than that in Western countries. Such

pressure may have led to the greater decline in smoking among older men who were more susceptible to the policy because of health concerns, to an extent not observed in Western countries. Another possible explanation for the decline in smoking prevalence among older men is cohort substitution. Older cohorts are replaced by younger cohorts with more education who are exposed to tobacco control policies earlier in life. Studies in Finland and the USA have reported decreases in smoking prevalence in younger cohorts relative to older cohorts.23,41 The present study also noted that smoking prevalence among young adult men aged 30–49 years did not decrease during 1992– 1999 but declined significantly in 2003. This may be explained by newly added or intensified tobacco control policies during 1999– 2002. A television anti-smoking campaign was started in 2000, and the 2002 campaign, which featured a famous comedian and actor with lung cancer, Mr. Ju-il Lee, brought national attention to smoking cessation. Moreover, the governmental budget started to increase substantially in 2000, which enabled effective antismoking education and advertising. In addition, shifting social norms regarding smoking have evolved in South Korea, further contributing to the decline in smoking prevalence among young adult men. In the past, most Korean men smoked and therefore smoking was regarded as normal behaviour among adult men. As the prevalence of smoking declined, smoking became an undesirable behaviour.42 Although the governmental budget for smoking cessation services increased significantly in 2005, smoking prevalence did not decrease significantly from 2003 to 2006 among younger men. The budget increase was mainly for smoking cessation clinics run by public health centres. A total of 163,962 men enrolled in smoking cessation clinics at public health centres, and the success

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rate for smoking cessation over 6 months was 36.6% in 2005.43 Considering the number of male smokers, the effect of smoking cessation clinics at public health centres was not likely to be visible in 2006, but provision of smoking cessation treatment by the public sector may influence smoking prevalence in the future. Based on the trends in smoking prevalence according to age group, some information about age-specific policy effects can be drawn from this study. First, the continuous increase in cigarette price likely contributed to the reduction of smoking prevalence among older men, but its effect was weaker among younger men aged 30–49 years. Smoking prevalence of younger men only dropped significantly in 2003, with much smaller declines in other periods, despite the cigarette price increases in 1994, 1996, 1999, 2001, 2002 and 2004. Townsend et al. and Chung et al. reported that the price elasticity of cigarette consumption among men aged 30–49 years is smaller than that among men aged 50 years.20,44 It seems that small price increases, such as 44 cents per pack in 2004, are not sufficient to reduce smoking prevalence among men aged 30–49 years, who are more active economically and less concerned for their health than older men. In order to affect younger men’s smoking, a greater increase in the price of cigarettes would be needed. Second, the marked reduction in smoking prevalence among younger men in 2003 was probably influenced by non-price tobacco control polices, which were notably intensified during 1999–2002. The budget for national anti-smoking education and advertising increased from $0.5 million in 1999 to $5.22 million in 2002. In particular, television anti-smoking advertisements started in 2000, and the budget for these advertisements accounted for the largest proportion of the total budget for tobacco control during this period. Comprehensive tobacco control policies were reported to be effective for reducing smoking prevalence among adults.45–47 More comprehensive and active policy measures including mass media advertising and substantial price increases may be needed, especially to reduce smoking prevalence among younger male adults. Several limitations of this study need to be considered. First, this study was an aggregate-level study; therefore, the results cannot necessarily be applied to individuals. The change in demographics and socio-economic position by year may also influence smoking prevalence. The period effect was adjusted by controlling for age, marital status and educational attainment. However, unmeasured sociodemographic characteristics such as an increase in immigrant workers may have influenced the results. Second, evaluation of the independent effect of each tobacco control policy is desirable to develop and implement more effective policy measures. However, the independent effect of each policy on smoking prevalence was difficult to assess directly in this study because a few tobacco control policies were implemented at the same time, and some policy measures such as provision of nonsmoking areas were intensified continuously in South Korea. The authors’ focus is on how smoking prevalence changed according to age group when national tobacco control policies evolved to more comprehensive and active measures. The quantification of the independent effects of tobacco control policies in South Korea requires further research, similar to the study of Levy et al.48 Third, selective mortality may have influenced the findings because smoking has a causal relationship with mortality. Jee et al. reported that the relative risk of smoking for total mortality in Korean men was 1.56 (95% confidence interval 1.52–1.59).49 However, the reduction in smoking prevalence among older men cannot be explained by selective mortality alone, because the quit ratio (proportion of past smokers among ever smokers) also increased to a similar extent by age. For example, quit ratios for groups aged 50–54, 60–64 and 70–74 years in 2006 were 42.34, 51.35 and 61.10%, respectively.

663

Fourth, smoking status was evaluated by self-assessment. However, previous studies have reported consistency between selfreports of smoking status and biochemical markers,50,51 and smoking by adult men is generally accepted in Korean society. Therefore, bias from self-reporting probably did not influence the results significantly. Fifth, the study definition of smoking prevalence included recent starters with lifetime smoking of fewer than 100 cigarettes. This may have slightly overestimated smoking prevalence compared with that in other studies that used WHO’s definition of smokers, i.e. those who have smoked at least 100 cigarettes in their lifetime.52 Despite these limitations, the present study is unique in showing the patterns of rapid smoking decline in South Korea by utilizing successive national representative data gathered before and after the implementation of government-directed tobacco control policies. The results of South Korea’s efforts to reduce smoking among men can serve as an example for many Asian countries. In conclusion, the findings of this study demonstrate the impact of tobacco control policies on the decline in smoking prevalence among Korean men, including young adults. The decline in smoking in South Korea seems to be the result of a dynamic interaction among individual factors, tobacco control policies and the social context for smoking. However, even with the remarkable decline, two-thirds of all 30-year-old Korean men still smoke, and almost 85% of men are ever smokers with an increased lifetime health risk. Most of the reduction in the male smoking rate to date has been the result of smoking cessation; a reduction in smoking initiation is not yet apparent in South Korea. Tobacco control activities targeted at reducing smoking initiation need to be strengthened in the future. Acknowledgements Dr. Howard Koh, former Director of the Division of Public Health Practice, Harvard School of Public Health, is currently the Assistant Secretary of Health in the U.S. Department of Health and Human Services (HHS). The article below was written prior to Dr. Koh’s appointment as the Assistant Secretary of Health and does not necessarily represent the views of HHS or the United States. Ethical approval None sought.

Funding None declared.

Competing interests None declared. References 1. Lopez AD, Collishaw NE, Piha T. A descriptive model of the cigarette epidemic in developed countries. Tob Control 1994;3:242–7. 2. van der Wilk EA, Jansen J. Lifestyle-related risks: are trends in Europe converging? Public Health 2005;119:55–66. 3. Giovino GA, Henningfield JE, Tomar SL, Escobedo LG, Slade J. Epidemiology of tobacco use and dependence. Epidemiol Rev 1995;17:48–65. 4. Garfinkel L. Trends in cigarette smoking in the United States. Prev Med 1997;26:447–50.

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