Soon-Woo Park

Validity of Self-Reported Height, Weight, and Body Mass Index of the Korea Youth Risk Behavior Web-Based Survey Questionnaire

OBJECTIVES Self-reported anthropometric values, such as height and weight, are used to calculate body mass index (BMI) and assess the prevalence of obesity among adolescents. The aim of this study was to evaluate the validity of self-reported height, weight, and BMI of the Korea Youth Risk Behavior Web-based Survey questionnaire. METHODS A convenience sample of 137 middle school students and 242 high school students completed a self-administered questionnaire in 2008. Body height and weight were directly measured after self-reported values were obtained from the questionnaire survey. Sensitivity, specificity, and kappa statistics were computed in order to evaluate the validity of the prevalence of obesity (BMI ≥ 95th percentile or ≥ 25 kg/m(2)) based on self-reported data. RESULTS Self-reported weight and BMI tended to be underestimated. Self-reported height tended to be overestimated among middle school females and high school males. Obese adolescents tended to underestimate their weight and BMI and overestimate their height more than non-obese adolescents. The prevalence estimate of obesity based on self-reported data (10.6%) was lower than that based on directly measured data (15.3%). The estimated sensitivity of obesity based on self-reported data was 69.0% and the specificity was 100.0%. The value of kappa was 0.79 (95% confidence interval, 0.70-0.88). CONCLUSIONS This study demonstrated that self-reported height and weight may lead to the underestimation of BMI and consequently the prevalence of obesity. These biases should be taken into account when self-reported data are used for monitoring the prevalence and trends of obesity among adolescents nationwide.

Validity of Self-reported Smoking Using Urinary Cotinine among Vocational High School Students

OBJECTIVES This study was conducted to validate self-reported smoking among high school students using urinary cotinine. METHODS A self report of smoking behavior was collected together with urine sample for cotinine analysis from 130 male and female students in two vocational high school students in November, 2007. Validity and agreement between self-reported smoking and urinary cotinine was analyzed with STATA 9.0 for different definitions of current smokers, and frequent and daily smokers. Urinary cotinine concentration was measured by the DRI Cotinine Assay for urine (Microgenics Corp., Fremont, CA) on Toshiba 200FR. The cut-off point of urinary cotinine was 50 ng/dl. RESULTS The concentrations of urinary cotinine were significantly different according to the frequency and amount of smoking. Sensitivity and specificity was 90.9% and 91.8% respectively, and the Cohens kappa value was 0.787 among the current smokers who smoked at least one day during one month preceding the survey. The comparable high sensitivity, specificity, and kappa value were shown also among the other definitions of current smokers, that is, subjective smokers, and weekly smokers. CONCLUSIONS The results showed the high validity of self-reported smoking among high school students. However, due to the small sample size and limitation of the participants, it is cautious to generalize the results to overall high school students.

Age at smoking initiation and subsequent smoking among Korean adolescent smokers.

Objectives: The aim of this study was to investigate the relationship between age at cigarette smoking initiation and smoking level among adolescent current smokers. Methods: In 2007, students from one or two classes of the 10th or 11th grade were randomly selected using the probability proportional to size sampling method. In total, 743 current smokers were included. Multiple logistic regression was used to determine the association between age at smoking initiation and smoking level as either frequent, daily, or heavy smokers. Results: The adjusted odds ratios for each smoking level were significantly higher for younger ages of smoking initiation than those for older ages of initiation were (p for trend <0.001). Compared with the students who started smoking in grades 10 to 11, the adjusted odds ratios for frequent, daily, and heavy smokers increased from 2.24 (95% confidence interval [CI], 1.30 to 3.87) to 3.90 (95% CI, 2.02 to 7.56), from 1.56 (95% CI, 0.92 to 2.62) to 3.17 (95% CI, 1.70 to 5.92), and from 2.56 (95% CI, 1.21 to 5.42) to 5.67 (95% CI, 2.61 to 12.30) with younger ages of smoking initiation. Conclusions: Smoking frequency and amount were closely associated with age at smoking initiation. Therefore, smoking prevention programs should be initiated from the young adolescent period.

Household and area income levels are associated with smoking status in the Korean adult population

BackgroundSome previous studies have suggested that area-level characteristics have effects on smoking. The aim of this study was to evaluate the associations between household income and area income on smoking in Korean adults.MethodsThis study was based on the Korean Community Health Survey (KCHS) performed in South Korea, between September and November 2009. In total, 222,242 subjects (103,124 men and 119,118 women) were included in the analysis. Information on smoking status was collected using a standardized questionnaire. Income status was determined by monthly household income. Household income was categorized as: <1 million won; <2 million won; <3 million won; and ≥3 million won. Area-level income categorized as quartiles. Data were analyzed using multilevel regression models. The analysis was conducted separately urban and rural, by sex.ResultsThe lowest household income group had a higher risk of smoking than the highest household income group in both urban and rural areas for both men and women after adjusting for individual characteristics (urban men: odds ration [OR], 1.44; 95% confidence interval [CI], 1.36–1.53; rural men: OR, 1.33; 95% CI, 1.25–1.42; urban women: OR, 2.38; 95% CI, 2.06–2.76; rural women: OR, 1.51; 95% CI, 1.25–1.83). In men, the lowest area-level income group had a higher risk for smoking than the highest area-level income group in urban areas after adjusting for individual characteristics and household income (OR, 1.17; 95% CI, 1.02–1.33). In women, the lowest area-level income group had a lower risk for smoking than the highest area-level income group in rural areas after adjusting for individual characteristics and household income (OR, 0.52; 95% CI, 0.39–0.70). However, no association was observed between area-level income and smoking in rural areas for men or in urban areas for women.ConclusionsThe results showed that smoking is strongly associated with household income status in both men and women, and area-level income is partly associated with smoking. Effects of area-level income on smoking differed by sex and region. These findings suggest that area characteristics have contextual effects on health related behavior independent of individual characteristics.

Predictors of Current Smoking among Male Students in a Technical High School: A Prospective Study

OBJECTIVES This study was performed using a longitudinal approach to explore the predictors for current smoking among male high school students. METHODS Baseline data was collected in May 2004 through a self-administrated questionnaire completed by 607 male students in a technical high school in Daegu city, Korea. Subsequently, their smoking behaviors were followed one year after. Among the 544 followed participants, data for 439 non-smokers in the first year was used in longitudinal analysis. Current smokers were defined as those respondents who had smoked one or more cigarettes within the 30 days preceding the survey. Several potential predictors for smoking were investigated including smoking history (never, experimental, former smoker), sociodemographic factors, environmental factors, attitudes toward smoking, and behavioral factors. Logistic regression was used to predict smoking with SPSS ver. 12.0. RESULTS According to multiple logistic regression analysis, those students who were more likely to smoke after one year were former smokers (OR: 2.12, 95% CI=1.01-4.44), current drinkers (OR: 2.55, 95% CI=1.33-4.89), who had four or five smokers among five best friends (OR: 3.43. 95% CI=1.14-10.30). In addition, those who had smokers among family members besides parents or siblings (OR: 1.66, 95% CI=0.92-2.98), exhibited a high level of subjective stress (OR: 1.77, 95% CI=0.96-3.26), or had a very good relationship with friends (OR: 1.93, 95% CI=0.99-3.75) were also more likely to smoke albeit with marginal statistical significance (p<0.1). CONCLUSIONS A smoking prevention program aimed at high school students may be more effective with due consideration of the predictors highlighted in this study. However, further studies with larger sample size and various target populations are necessary to find potential predictors not found in this study but suggested in other longitudinal studies.

The Current Status and Problems of Tobacco Control Programs of Public Health Centers in Korea

Objectives: This study was conducted to suggest the way to improve the tobacco control program of public health centers in Korea. Methods: A survey with a self-administered questionnaire was conducted among 246 persons in charge of tobacco control work in public health centers nationwide in December, 2006. Frequency analysis was performed with a final sample of 212 respondents with SPSS 12.0 for Windows. Results: The duration of engagement in tobacco control work was less than 3 years among 86.7% of respondents, and 87.3% of respondents had other duties besides tobacco control. Almost all public health centers conducted a campaign with posters or leaflets, and smoking prevention education among adolescents. The actual priority for programs was based on the community diagnosis in only 33.5% of the cases. Only 1.9% of respondents complained lack of budget, on the other hand, 44.7% of respondents appealed insufficient number of personnel. The route of knowledge and skill was largely dependent on self-learning or information from colleague. Collaboration with other related department was done well in 39.5% of the cases. The majority of respondents was satisfied with the general support from central government. Conclusions: To improve the tobacco control program of public health centers, it is needed the reinforcement of capacity and specialty among personnel, priority setting and performance of programs based on the scientific evidence, induction of community participation, utilization of community human resources, development of education and training course for practical skill, effective networking among departments.

Health Behaviors among Adolescents in the Rural Area in Korea

The data source was the Korea Youth Risk Behavior Web-based Survey in 2005. With two stage cluster sampling, a total of 58,224 sample was selected from 799 middle and high schools nationwide. The area was classified into county area, small to medium city, and large city, and then the county area was considered as a rural area. Data was analyzed with STATA 9.0 using the method of complex survey data analysis considering sampling weight, strata, and primary sampling unit.

Association between Peer Cigarette Smoking and Electronic Cigarette Smoking among Adolescent Nonsmokers: A National Representative Survey.

We assessed the association between electronic cigarette (e-cigarette) use and peer cigarette smoking, a major risk factor for the initiation of cigarette smoking in adolescents. Data from the 2013 Korea Youth Risk Behavior Web-based Survey of 65,753 nonsmokers aged 13–18 years were analyzed using multiple logistic regression. A total of 3.8% of the Korean adolescents were ‘ever e-cigarette’ users and 1.2% were current users. Adjusted odds ratios (ORs) for current and ever e-cigarette use compared to those whose closest friends were non-smokers ranged from 2.05 (95% confidence interval [CI], 1.82–2.30) to 5.50 (95% CI, 4.77–6.34), and from 2.23 (95% CI, 1.77–2.81) to 7.82 (95% CI, 5.97–10.25) for those who had ‘some’ close friends to ‘most/all’ friends who smoked, respectively. The slopes of the adjusted ORs for e-cigarette use in ‘never smokers’ were more than twice as steep as those in ‘former smokers’, showing a significant interaction effect between the proportion of smoking closest friends and cigarette smoking status (never or former smokers) (p<0.001 for interaction). Peer cigarette smoking had a significant association with e-cigarette use in adolescent nonsmokers, and this association was greater on never smokers than former smokers.

Modifying Effect of Suicidal Ideation on the Relationship Between Asthma and Cigarette Use Behaviors Among Korean Adolescents

Objectives Although cigarette smoking is known to be related to the exacerbation of asthma symptoms, several studies have indicated that the prevalence of cigarette smoking among asthmatic adolescents is similar to or even higher than that among non-asthmatic adolescents. The aim of this study was to evaluate the relationship between asthma and cigarette use behaviors and whether or not the presence of suicidal ideation modifies this relationship among Korean adolescents. Methods We analyzed data from the 2008 Korea Youth Risk Behavior Web-based Survey, which included a nationally representative sample of middle and high school students. Multiple logistic regression models were used to calculate odd ratios and 95% confidence intervals of cigarette use behaviors among current asthmatics, former asthmatics, and non-asthmatics, after adjusting for gender, grade, school records, socioeconomic status, current alcohol use, and suicidal ideation. Results Of 75 238 study participants, 3.5% were current asthmatics and 4.5% were former asthmatics. Compared with non-asthmatics, asthmatics were more likely to report current cigarette use, frequent and heavy cigarette use, and cigarette use before 13 years of age. There were statistically significant interactions between asthma and suicidal ideation in cigarette use behaviors. Conclusions This study demonstrated that asthmatic adolescents are more likely than non-asthmatic adolescents to engage in cigarette use behaviors and the presence of suicidal ideation is an effect modifier of the relationship between asthma and cigarette use behaviors. Particular attention should be paid to the awareness of health risks of cigarette smoking and mental health problems among asthmatic adolescents.