BACKGROUND: It is still unclear whether individuals with the same degree of obesity but different weight histories since young adulthood have different insulin concentration, prevalence of metabolic syndrome components and their clustering.
METHODS: A cross-sectional study was conducted on 3,399 (for weight difference analysis) and 1,879 (for weight fluctuation analysis) Japanese men aged 40-59 years. Weight difference was calculated by subtracting the recalled weight at about 25 years old from the current weight. The root mean square error around the slope of weight on age (weight - RMSE) was calculated by a simple linear regression model, in which the subject's actual weights at ages 20, 25, 30, 40 years and 5 years prior to the study, as well as current weight, were dependent variables against the subject's age as the independent variable. Each metabolic syndrome component was defined as follows: serum triglycerides ≥150 mg/dL; HDL-cholesterol <40 mg/dL; fasting glucose ≥110 mg/dL; and blood pressure ≥140/90 mm Hg.
RESULTS: Those who gained <10%, <20%, or 20% or more in weight had a significantly higher than unity odds ratio of having two or more metabolic syndrome components in relation to those whose weight remained stable: 1.28 (95% confidence interval: 0.95-1.73), 2.49 (1.91-3.24), and 5.30 (3.97-7.07), respectively. Weight-RMSE was significantly and positively associated with fasting insulin concentration independent of current weight, weight-slope or other lifestyle-related factors.
CONCLUSIONS: Metabolic syndrome components would likely tend to cluster more in individuals with large weight gain on a physiologic basis characterized by high fasting insulin concentration. Furthermore, weight fluctuation was suggested to increase the risk of fasting hyperinsulinemia.
J Epidemiol 2007; 17: 141-146.

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BACKGROUND: New training programs need to be developed to help Chinese smokers achieve quitting. The objective of this study was to assess the effectiveness of a group smoking cessation intervention based on social cognitive theory among Chinese smokers.
METHOD: A total of 225 smokers were eligible for the study and were randomly assigned to an intervention group (n=118) and a control group (n=107). The intervention group received the course soon after a baseline survey, whereas the control group received routine training in the first 6 months, and then took the same course. Effectiveness was evaluated at 6-month and 1-year follow-up from baseline.
RESULTS: After 6 months, 40.5% (47/116) in the intervention group and 5.0% (5/101) in the control group quit smoking (absolute risk reduction: 35.5% [95% confidence interval (CI): 24.2-46.8%]). The 6-month continuous abstinence rate was 28.4% (33/116) in the intervention group and 3.0% (3/101) in the control group (absolute risk reduction 25.4% [95% CI: 15.6-35.2%]). At 1-year follow-up, the proportion of quitting and the 6-month abstinence rate in the intervention group were 35.8% and 22.0%, respectively. The factors associated with smoking cessation during the 6 month period were intervention (adjusted odds ratio [OR]=6.42 [95% CI: 2.46-13.28]), as well as anticipation of quitting (adjusted OR=1.46 [95% CI: 1.12-1.91]) and skill self-efficacy score in the baseline (adjusted OR=1.04 [95% CI: 1.01-1.07]). The same intervention was conducted in the control group after the 6-month study, in which a similar intervention effect was observed.
CONCLUSION: A smoking cessation intervention based on social cognitive theory among Chinese smokers is highly effective.
J Epidemiol 2007; 17: 147-155.

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BACKGROUND: Little is known about the genetic risk factors associated with colorectal cancer. Although the Ser326Cys polymorphism of 8-oxoguanine DNA glycosylase (hOGG1) is consistently associated with a range of cancers, there is no consensus regarding this polymorphism and colorectal cancer risk.
METHODS: In the present study, conducted in a Korean population, we used the TaqMan assay to investigate whether the hOGG1 Ser326Cys polymorphism was associated with colorectal cancer in 439 colorectal cancer patients and 676 healthy normal controls. We also examined whether the hOGG1 Ser326Cys polymorphism is associated with tumor location, microsatellite instability (MSI) status and tumor-node-metastasis (TNM) stage in colorectal cancer.
RESULTS: We found no significant difference between the cancer and control populations in terms of genotype distribution (CC, CG and GG). In addition, we found no association between the hOGG1 Ser326Cys polymorphism and cancer risk, MSI status, TNM stage or tumor location in colorectal cancer patients.
CONCLUSIONS: These results suggest that unlike for other cancer types, the hOGG1 Ser326Cys polymorphism is not a major genetic risk factor for colorectal cancer.
J Epidemiol 2007; 17: 156-160.

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BACKGROUND: Studies from industrialized Western countries have reported an inverse association between socioeconomic status and overweight/obesity. In contrast, few studies from newly industrialized countries in Asia have examined this association. In this context, we examined the association between socioeconomic status and overweight/obesity by gender in Chinese adults in Singapore.
METHODS: A population-based cross sectional study of 942 participants (57.3% women, 40-81 years) residing in the Tanjong Pagar district of Singapore was conducted. Education, income, and housing type were used as socioeconomic status indicators. Main outcome-of-interest was the presence of overweight/obesity (n=313), classified by body mass index as overweight (25- 29.9 kg/m²), or obese (≥30 kg/m²)
RESULTS: The prevalence of overweight/obesity was 33% in men and 34% in women. In men, SES indicators were not associated with overweight/obesity. In women, SES indicators were found to be inversely associated with overweight/ obesity. Compared to women with secondary/higher education, the odds ratio (OR) (95% confidence interval [CI]) of overweight/obesity in women with primary/lower education was 2.5 (1.5-4.0). Compared to women earning > Singapore dollar (SGD) 1,000 per month, the OR (95% CI) of overweight/obesity among women earning ≤SGD 1,000 was 2.5 (1.4-4.5). Compared to women living in large size public apartments or private houses, the OR (95% CI) of overweight/obesity in women living in small/medium size public apartments was 1.8 (1.2-2.7).
CONCLUSIONS: Lower socioeconomic status, defined by education, income, and housing type was associated with overweight/obesity in Chinese Singaporean women.
J Epidemiol 2007; 17: 161-168.

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BACKGROUND: Few biological markers that allow evaluation of the effects of air pollution on human health have been identified. This study evaluated the association of serum C-reactive protein (CRP) concentration in children with their respiratory symptoms and air pollution.
METHODS: Respiratory symptoms and serum concentrations of CRP were examined in 2,094 school children living in 3 communities with different concentrations of air pollutants in Chiba Prefecture, Japan in 2001. The relationships between serum CRP concentration and sex, age, respiratory symptoms, and various environmental factors were analyzed.
RESULTS: Serum CRP concentration decreased with age, and was significantly higher both in children who were bottle-fed in infancy and whose mothers smoked. Children with wheeze had significantly higher serum CRP concentration than those without wheeze. After adjustment for potential confounding factors, increased serum CRP concentrations of the 90th percentile (1.4 mg/L) or above were significantly associated with atmospheric concentration of suspended particulate matter (SPM) (odds ratio [OR] =1.49 for the range of observed concentrations, 95% confidence interval [CI]: 1.07-2.06) and sulfur dioxide (SO₂) (OR =1.45, 95% CI: 1.04-2.03). In a two-pollutant model including SPM and nitrogen dioxide (NO₂) concentrations, increased serum CRP concentrations were also associated with SPM (OR =1.94, 95% CI: 1.08-3.50), but no such association was found with NO₂ (OR =0.62, 95% CI: 0.26-1.48).
CONCLUSION: Serum CRP concentration is related to wheezing and the degree of air pollution. Because the concentrations of air pollutants are highly correlated, it is difficult to elaborate on which pollutant has a stronger effect on serum CRP concentrations.
J Epidemiol 2007; 17: 169-176.

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