The stages of change in smoking cessation in a representative sample of Korean adult smokers.

This study reports the stages of change in smoking cessation in a representative sample of Korean adult smokers. The study subjects, all adult smokers (n=2,422), were recruited from the second Korea National Health and Nutrition Examination Survey conducted in 2001. The stages of change were categorized using demographic (age and sex), socioeconomic (education, residence, and household income), and smoking characteristics (age at smoking onset, duration of smoking, and number of cigarettes smoked per day). Age-stratified analyses of the association of socioeconomic and smoking characteristics with the stages of change in male and female smokers were also conducted. According to the stages of change, the study population consisted of 37.6% (95% CI, 35.7-39.5) pre-contemplation, 56.0% (54.0-58.0) contemplation, and 6.4% (5.4-7.4) preparation. The associations between the characteristics of the smokers and the stages of change were all statistically significant. The age-stratified analyses showed that all the socioeconomic and smoking characteristics were significantly associated with the stages in males, while education and residence had significant associations in females. This study revealed that a relatively small number of Korean smokers were prepared to quit and the stage distribution might be influenced by demographic, socioeconomic, and smoking characteristics.

INTRODUCTION

Smoking is one of the most serious public health issues in the world. Despite a recent downward trend, smoking remains the most serious public health problem in Korea. Respiratory morbidities are significantly higher in children who had a smoking parent than in those who had not (1). In 1999, premature death due to smoking was estimated at 57.7% in males and 11.4% in females in Korea (2).

A variety of individual and population-based interventions aimed at smoking cessation have been developed. The transtheoretical model is a conceptual theory that has commonly been used for behavioral modification in areas such as smoking cessation, dieting, regular exercise, and seatbelt use (3-5). One of the major contributions of the model is the recognition that individuals progress through a series of stages: recognizing the need to change, contemplating a change, making a change, and finally sustaining the new behavior. The "stages of change" is a central concept in the transtheoretical model. Smokers can be classified into one of three stages. Pre-contemplation describes smokers who are not thinking of quitting. Contemplation describes smokers who consider quitting in the next 6 months. Preparation describes smokers who intend to quit in the next 30 days and have made a 24-hr quit attempt in the past year. According to the definition, smokers who intend to quit in the next 30 days but have no quit attempt in the past year are not classified into preparation but contemplation stage (6, 7).

Stage-matched interventions can be individualized in response to the needs and characteristics of the individual. Examples of such interventions include stage-matched manuals, short counselor calls, and expert system interventions (8, 9). In addition, the stage of change for smoking cessation has important implications in public health (10). To design interventions that are appropriate for an entire population, information on the stage distribution of smokers in a general population is necessary. Velicer et al. reported the stage distributions for three samples of smokers in the United States (smokers from the states of Rhode Island and California and a total of 114 workplaces in four different geographic locations) and found that approximately 40% were in the pre-contemplation stage, 40% were in the contemplation stage, and 20% were in the preparation stage (11). A study that examined a population of smokers in an Australian general medical practice found that 37, 42, and 21% were in the respective stages (12). However, the stages of change in smoking cessation among Korean smokers have never been reported. Therefore, this study describes the stages of change in a representative sample of Korean adult smokers.

MATERIALS AND METHODS

The subjects in this study were recruited from participants in the second Korea National Health and Nutrition Examination Survey (K-NHANES) conducted in 2001. The K-NHANES randomly sampled the general Korean population to assess health and nutritional statuses through interviews and health examinations (13).

Of the 37,769 Koreans who provided health and nutrition information for the second K-NHANES, 7,922 adults (aged≥20) reported their smoking status. Among these, 2,223 males and 226 females were identified as current smokers. We excluded 27 smokers because they did not report a readiness to quit smoking. As a result, 2,422 smokers remained for analysis.

We used two questions from the questionnaire of the second K-NHANES to classify the stages of smokers. The questions were as follows:

Q1. In the last year, have you tried to quit smoking?

Yes

No

Q2. Are you planning to quit smoking within the next one to 6 months?

Thinking of quitting smoking within the next month

Thinking of quitting smoking within the next 6 months

Thinking of quitting smoking at some point, but not within the next 6 months

Absolutely not thinking of quitting

In this study, the stages of change was defined as follows:

Pre-contemplation: The smokers who responded 4) to Q2

Contemplation: The smokers who responded 2) or 3) to Q2, and those who responded 1) to Q2 and 2) to Q1

Preparation: The smokers who responded 1) to Q2 and 1) to Q1

The stages of change in smoking cessation were categorized using demographic (age and sex), socioeconomic (education, residence, and household income), and smoking characteristics (age at smoking onset, duration of smoking, and number of cigarettes smoked per day), as previous studies have found that these characteristics are imporefore, sex-specific age-stratified analyses for the association of socioeconomic and smoking characteristics with the stages of chantant (14-18). The percentages of the survey participants in each stage and the 95% confidence intervals were evaluated using demographic, socioeconomic, and smoking characteristics. The Mantel-Haenszel chi-square analysis was used to test trends for individual associations between characteristics and the stages of change.

Age and sex are the most important determinants of health behaviors, including smoking (19). In addition, the reported smoking prevalence in Korean women was much lower than that in Korean men (20). Therge were conducted. The Cochran-Mantel-Haenszel statistics were used to evaluate the statistical significance of these analyses. All the statistical analyses in this study were conducted using the PROC FREQ procedure of the SAS statistical package (21).

RESULTS

The overall smoking prevalence in the adult participants who reported their smoking status (n=7,922) was 30.9% (95% CI, 29.9-31.9). The smoking prevalence was 61.6% (60.0-63.2) in adult Korean males and 5.2% (4.6-5.9) in adult Korean females.

Table 1 shows the distribution of the stages of smoking cessation with their 95% confidence intervals by demographic, socioeconomic, and smoking-related variables. According to the stages of change, the study population consisted of 37.6% (35.7-39.5) pre-contemplation, 56.0% (54.0-58.0) contemplation, and 6.4% (5.4-7.4) preparation. As age increased, the proportion of smokers in the contemplation and preparation stages declined, while the percentage in the pre-contemplation stage increased. A greater percentage of males were in the preparation stage, while a greater percentage of females were in the pre-contemplation stage.

Table 1

Distribution of the stages of change in smoking cessation with 95% confidence intervals by demographic, socioeconomic, and smoking characteristics

As education increased, the percentage of smokers in the pre-contemplation stage declined, while the percentages in the contemplation and preparation stages increased. A smaller percentage of smokers residing in rural areas were in the preparation stage compared to those residing in cities. The percentage of smokers in the pre-contemplation stage declined as household income increased, while the percentages in the contemplation and preparation stages increased.

Smokers who started smoking at or after 30 yr of age tended to include a greater percentage in the pre-contemplation stage and smaller percentages in the contemplation and preparation stages than those who started smoking when they were younger than 30. Smokers who began smoking when they were 20-29 yr old showed the greatest percentage in the preparation stage among all the age groups. The proportion of smokers in the pre-contemplation stage increased as the duration of smoking increased, while the proportions in the contemplation and preparation stages declined. As the number of cigarettes smoked per day decreased, the proportion of smokers in the preparation stage increased. The observed trends between the characteristics of the smokers and the stages of change were all statistically significant.

The age-stratified analyses showed that all the socioeconomic and smoking characteristics had significant associations with the stages of change in male smokers. After adjusting for age, the proportion of male smokers in the preparation stage increased with education, in urban residents, with household income, for a late age of smoking onset, in those with a short duration of smoking, and in those who smoked a few cigarettes per day (Table 2).

Table 2

Age-stratified analyses of the association of socioeconomic and smoking characteristics with the stages of change in smoking cessation in male smokers (n=2,200)

PC, pre-contemplation; C, contemplation; P, preparation; CMH, Cochran-Mantel-Haenszel statistic.

The age-stratified analyses showed that education and residence had significant associations with the stages of change in female smokers (p<0.05). After adjusting for age, the proportion of female smokers in the preparation stage increased with education and in urban residents (Table 3).

Table 3

Age-stratified analyses of the association of socioeconomic and smoking characteristics with the stages of change in smoking cessation in female smokers (n=222)

Abbreviations are same as Table 2.

DISCUSSION

This study revealed that a relatively small number of Korean adult smokers were prepared to quit smoking compared to the stage distributions found in three samples from the United States and in an Australian general medical practice (11, 12). However, caution must be exercised when making a comparison of the stage distributions based on different studies. The definitions of the stages and the questionnaires used to classify smokers have been modified since the concept of the stages of change was first introduced (22). The definition of the stages and questionnaire used in this study were not exactly same as those used in previous studies (6, 7, 11, 12). Our subjects were a random sample of the general Korean population, while those of the previous American and Australian studies did not represent the general populations of the respective nations. Our results were similar to the population-based national estimates of the stage of change among daily smokers in the United States who responded to the Current Population Survey during the 1990s; in 1992-1993, 59.1, 33.2, and 7.7% of the respondents were pre-contemplators, contemplators, and in the preparation stage respectively. This distribution was similar in subsequent surveys (1995-1996; 1998-1999) (23). Therefore, the characteristics of the subjects must be considered when interpreting stage distributions from different studies.

Our study suggests that the stage distribution of smokers could be influenced by demographic, socioeconomic, and smoking characteristics. Therefore, interventions for transition between the stages of change in smokers should be modified according to the characteristics of the smokers. Both clinical (individual) and public health (population) approaches to treat smokers, especially those who are unwilling to attempt quitting, are needed. On an individual level, a clinician or health care professional can motivate smokers who are in the pre-contemplation and contemplation stages to quit smoking by presenting the benefits of quitting in regard to current and future health, emphasizing the negative consequences of tobacco use and potential benefits of quitting, identifying barriers to quitting, and discussing coping strategies (24, 25). In addition, public health approaches such as tobacco tax increases, the extension to non-smoking areas, the prohibition of tobacco advertisements, and the printing of warning phrases or pictures on tobacco products have been suggested and implemented to induce smokers to quit (26).

The age-stratified analyses showed that all the socioeconomic and smoking characteristics had significant associations with the stages in males, while education and residence had significant associations with the stages in females. This suggests that socioeconomic and smoking characteristics influence the stages of change in male and female smokers in different ways. However, this study could not confirm this point due to the small number of female smokers. Further studies on the differences in smoking behaviors and the stages of change between male and female smokers are needed.

Corresponding to the need to stop smoking to protect public health, the Korean government has implemented various anti-smoking approaches since 2000. In addition to public health approaches, a smoking cessation program at the clinic level was introduced to all public health centers in Korea in 2005. The low proportion of Korean adult smokers in the preparation stage in this study might be due to the recent implementation of these anti-smoking approaches, which may not have had enough time to produce significant effects. The third K-NHANES was still in progress when we conducted this study, and its data were unavailable. Therefore, we used the data obtained from second K-NHANES in this study. Further studies are needed to follow the changes in the stage distribution and to evaluate the effectiveness of anti-smoking programs.