Smoking Cessation and Short- and Longer-Term Mortality.

BACKGROUND: Smoking cessation reduces mortality and morbidity. However, the extent and rapidity at which cessation reduces contemporary death rates from smoking-related illnesses remain uncertain. METHODS: We pooled current or former versus never cigarette smoker hazard ratios from four national cohorts with linkage to death registries in the United States, United Kingdom, Norway, and Canada among adults 20 to 79 years of age from 1974 to 2018. We calculated excess risk differences and survival, comparing current or never smokers with age-specific cessation and cessation fewer than 3, 3 to 9, or 10 or more years earlier. RESULTS: Among 1.48 million adults followed for 15 years, 122,697 deaths occurred. Adjusting for age, education, alcohol use, and obesity, current smokers had higher hazard ratios for death compared with never smokers (2.8 for women, 2.7 for men). Survival between 40 and 79 years of age was 12 and 13 years less in women and men, respectively, who smoked compared with never smokers (about 24 to 26 years of life lost for smokers who died from smoking combined with zero loss for smokers who did not die from smoking). Former smokers showed lower hazard ratios (1.3 in both women and men). Short-term cessation for fewer than 3 years was associated with a lower excess risk of 95% in women and 90% in men younger than 40 years of age, with notable beneficial associations also in women and men 40 to 49 years of age (81% and 61%, respectively) and 50 to 59 years of age (63% and 54%, respectively). Cessation at every age was associated with longer survival, particularly cessation before 40 years of age. Among all ages and compared with continued smoking, cessation of fewer than 3 years potentially averted 5 years of life lost and cessation for 10 or more years averted about 10 years of life lost, yielding survival similar to that of never smokers. CONCLUSIONS: Quitting smoking at any age, but particularly in younger years, was associated with lower excess mortality overall and from vascular, respiratory, and neoplastic diseases. Beneficial associations were evident as early as 3 years after cessation. (Funded by Canadian Institutes of Health Research [FDN-154277].)

Assessment of SARS-CoV-2 Seropositivity During the First and Second Viral Waves in 2020 and 2021 Among Canadian Adults.

Importance: The incidence of infection during SARS-CoV-2 viral waves, the factors associated with infection, and the durability of antibody responses to infection among Canadian adults remain undocumented. Objective: To assess the cumulative incidence of SARS-CoV-2 infection during the first 2 viral waves in Canada by measuring seropositivity among adults. Design, Setting, and Participants: The Action to Beat Coronavirus study conducted 2 rounds of an online survey about COVID-19 experience and analyzed immunoglobulin G levels based on participant-collected dried blood spots (DBS) to assess the cumulative incidence of SARS-CoV-2 infection during the first and second viral waves in Canada. A sample of 19 994 Canadian adults (aged ≥18 years) was recruited from established members of the Angus Reid Forum, a public polling organization. The study comprised 2 phases (phase 1 from May 1 to September 30, 2020, and phase 2 from December 1, 2020, to March 31, 2021) that generally corresponded to the first (April 1 to July 31, 2020) and second (October 1, 2020, to March 1, 2021) viral waves. Main Outcomes and Measures: SARS-CoV-2 immunoglobulin G seropositivity (using a chemiluminescence assay) by major geographic and demographic variables and correlation with COVID-19 symptom reporting. Results: Among 19 994 adults who completed the online questionnaire in phase 1, the mean (SD) age was 50.9 (15.4) years, and 10 522 participants (51.9%) were female; 2948 participants (14.5%) had self-identified racial and ethnic minority group status, and 1578 participants (8.2%) were self-identified Indigenous Canadians. Among participants in phase 1, 8967 had DBS testing. In phase 2, 14 621 adults completed online questionnaires, and 7102 of those had DBS testing. Of 19 994 adults who completed the online survey in phase 1, fewer had an educational level of some college or less (4747 individuals [33.1%]) compared with the general population in Canada (45.0%). Survey respondents were otherwise representative of the general population, including in prevalence of known risk factors associated with SARS-CoV-2 infection. The cumulative incidence of SARS-CoV-2 infection among unvaccinated adults increased from 1.9% in phase 1 to 6.5% in phase 2. The seropositivity pattern was demographically and geographically heterogeneous during phase 1 but more homogeneous by phase 2 (with a cumulative incidence ranging from 6.4% to 7.0% in most regions). The exception was the Atlantic region, in which cumulative incidence reached only 3.3% (odds ratio [OR] vs Ontario, 0.46; 95% CI, 0.21-1.02). A total of 47 of 188 adults (25.3%) reporting COVID-19 symptoms during phase 2 were seropositive, and the OR of seropositivity for COVID-19 symptoms was 6.15 (95% CI, 2.02-18.69). In phase 2, 94 of 444 seropositive adults (22.2%) reported having no symptoms. Of 134 seropositive adults in phase 1 who were retested in phase 2, 111 individuals (81.8%) remained seropositive. Participants who had a history of diabetes (OR, 0.58; 95% CI, 0.38-0.90) had lower odds of having detectable antibodies in phase 2. Conclusions and Relevance: The Action to Beat Coronavirus study found that the incidence of SARS-CoV-2 infection in Canada was modest until March 2021, and this incidence was lower than the levels of population immunity required to substantially reduce transmission of the virus. Ongoing vaccination efforts remain central to reducing viral transmission and mortality. Assessment of future infection-induced and vaccine-induced immunity is practicable through the use of serial online surveys and participant-collected DBS.

Epstein-Barr Virus Antibody Titers Are Not Associated with Gastric Cancer Risk in East Asia.

BACKGROUND: Epstein-Barr virus (EBV)-positive gastric cancers represent a distinct subtype of gastric cancers and account for nearly 10% of the gastric cancer burden, yet risk detection strategies for this cancer subtype are lacking. METHODS: We conducted a nested case-control study where we assayed 4 EBV antigens [viral capsid antigen (VCA), early antigen (EA), Epstein-Barr nuclear antigen (EBNA), and BZLF1-encoded replication activator protein (ZEBRA)] in either sera or plasma from 1447 gastric cancer cases and 1797 controls obtained from seven prospective cohorts representing individuals from the high gastric cancer-risk countries of China, Japan, and Korea. RESULTS: The prevalence of EBV sero-positivity was universal with the exception of one sero-negative individual, and the highest titers of the EBV antigens VCA (OR 0.95, 95% CI 0.78-1.17), EBNA (OR 0.88, 95% CI 0.72-1.08), EA (OR 0.97, 95% CI 0.79-1.19), and ZEBRA (OR 0.87, 95% CI 0.71-1.07) were not associated with risk of incident gastric cancer. When we stratified these data by H. pylori status, there was no change in the association. CONCLUSIONS: Multiplex serology of the aforementioned EBV antigens in serum may not be a suitable biomarker for predicting gastric cancer risk in East Asian populations.

Association between serum persistent organic pollutants and DNA methylation in Korean adults.

BACKGROUND: Exposure to persistent organic pollutants (POPs) has been associated with epigenetic changes such as DNA methylation, which can influence human health. However, the association between POPs and DNA methylation by sex was not shown in previous studies. OBJECTIVES: We investigated the association between POPs and DNA methylation in men and women using a larger population. METHODS: A cross-sectional study was conducted using the data of 444 Koreans (253 men and 191 women). Measurements for sixteen different POPs, including six organochlorine pesticides (OCPs) and ten polychlorinated biphenyls (PCBs) were taken in serum. DNA methylation via Alu and LINE-1 in peripheral leukocytes was measured by pyrosequencing. To evaluate the association between POPs and DNA methylation, the Pearson's correlation and multiple linear regression analyses were performed. RESULTS: Except for PCB52 and PCB101, we found significant inverse associations between p,p'-DDE, cis-Heptachlor epoxide, and PCBs and Alu assay in men after adjusting for age, BMI, smoking status, and alcohol consumption (ß = -0.67 for p,p'-DDE; -0.28 for cis-Heptachlor epoxide; in the range from -0.43 to -1.60 for PCBs). In women, PCB153 and PCB180 showed statistically significant inverse association with Alu assay (ß = -0.22 for PCB153; -0.22 for PCB180). Except for PCB101, p,p'-DDE and PCBs were positively associated with LINE-1 assay in women (ß = 0.48 for p,p'-DDE; in the range from 0.40-0.89 for PCBs) while p,p'-DDE, PCB153, and PCB180 showed positive associations with LINE-1 assay in men (ß = 0.55 for p,p'-DDE; 0.65 for PCB153; 1.02 for PCB180). CONCLUSIONS: We found that several POPs were associated with global DNA hypomethylation in the Alu assay for men and global DNA hypermethylation in the LINE-1 assay for women.

Biological age as a useful index to predict seventeen-year survival and mortality in Koreans.

BACKGROUND: Many studies have been conducted to quantitatively estimate biological age using measurable biomarkers. Biological age should function as a valid proxy for aging, which is closely related with future work ability, frailty, physical fitness, and/or mortality. A validation study using cohort data found biological age to be a superior index for disease-related mortality than chronological age. The purpose of this study is to demonstrate the validity of biological age as a useful index to predict a person's risk of death in the future. METHODS: The data consists of 13,106 cases of death from 557,940 Koreans at 20-93 years old, surveyed from 1994 to 2011. Biological ages were computed using 15 biomarkers measured in general health check-ups using an algorithm based on principal component analysis. The influence of biological age on future mortality was analyzed using Cox proportional hazards regression considering gender, chronological age, and event type. RESULTS: In the living subjects, the average biological age was almost the same as the average chronological age. In the deceased, the biological age was larger than the chronological age: largest increment of biological age over chronological age was observed when their baseline chronological age was within 50-59 years. The death rate significantly increased as biological age became larger than chronological age (linear trend test, p value < 0.0001). The largest hazard ratio was observed in subjects whose baseline chronological age was within 50-59 years when the cause was death from non-cancerous diseases (HR = 1.30, 95% confidence intervals = 1.26 - 1.34). The survival probability, over the 17 year term of the study, was significantly decreased in the people whose biological age was larger than chronological age (log rank test, p value < 0.001). CONCLUSIONS: Biological age could be used to predict future risk of death, and its effect size varied according to gender, chronological age, and cause of death.

Body mass index and incidence of thyroid cancer in Korea: the Korean Cancer Prevention Study-II.

PURPOSE: The prevalence of thyroid cancer and obesity has increased worldwide. However, their association has remained controversial and few studies have been performed in Asia. Our study evaluated the correlation between the incidence of thyroid cancer and body mass index (BMI) in Korea. METHODS: This is a multi-centered, prospective cohort study from the Korean Cancer Prevention Study-II. A total of 141,157 individuals between 1994 and 2012, including 1546 newly developed thyroid cancer patients, were enrolled. Subjects were divided into four groups on the BMI. Person-years, incidence rate, and hazard ratios (HRs) were calculated using the Cox proportional hazard model. RESULTS: The increasing trends of HRs of thyroid cancer in men and women younger than 50 years of age were observed as BMI increased (P trend <0.001 in both groups). However, in women older than 50 years of age, there was no association between thyroid cancer incidence and BMI. CONCLUSIONS: Our findings suggest that positive association between thyroid cancer incidence and high BMI in men and women under 50 years old. Based on these results, we suggest that obese men and women under 50 years old are better to be considered for the higher possibility of thyroid cancer development, and more efforts are needed to control weight gain.

Fruit and vegetable consumption, Helicobacter pylori antibodies, and gastric cancer risk: A pooled analysis of prospective studies in China, Japan, and Korea.

Epidemiological findings on the association between fruit and vegetable consumption and gastric cancer risk remain inconsistent. The present analysis included 810 prospectively ascertained non-cardia gastric cancer cases and 1,160 matched controls from the Helicobacter pylori Biomarker Cohort Consortium, which collected blood samples, demographic, lifestyle, and dietary data at baseline. Conditional logistic regression adjusting for total energy intake, smoking, and H. pylori status, was applied to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for gastric cancer risk across cohort- and sex-specific quartiles of fruit and vegetable intake. Increasing fruit intake was associated with decreasing risk of non-cardia gastric cancer (OR = 0.71, 95% CI: 0.52-0.95, p trend = 0.02). Compared to low-fruit consumers infected with CagA-positive H. pylori, high-fruit consumers without evidence of H. pylori antibodies had the lowest odds for gastric cancer incidence (OR = 0.12, 95% CI: 0.06-0.25), whereby the inverse association with high-fruit consumption was attenuated among individuals infected with CagA-positive H. pylori (OR = 0.82, 95% CI: 0.66-1.03). To note, the small number of H. pylori negative individuals does influence this finding. We observed a weaker, nondose-response suggestion of an inverse association of vegetable intake with non-cardia gastric cancer risk. High fruit intake may play a role in decreasing risk of non-cardia gastric cancer in Asia.

Helicobacter pylori blood biomarker for gastric cancer risk in East Asia.

BACKGROUND: Incidence and mortality rates for gastric cancer, the fifth most commonly diagnosed and third most deadly cancer worldwide, are highest in East Asia. We sought to identify gastric cancer risk biomarkers among eight prospective studies from China, Japan and Korea. METHODS: This pooled nested case-control study included 1608 incident non-cardia gastric cancer cases and 1958 matched controls. Pre-diagnostic antibody levels to 15 Helicobacter pylori proteins were assessed using multiplex serology. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Sero-positivity to 10 H. pylori antigens (Omp, CagA, VacA, HcpC, HP 0305, GroEL, NapA, HyuA, Cad, HpaA) was associated with a 1.29- to 3.26-fold increase in odds of gastric cancer. Omp and HP 0305 consistently remained associated with gastric cancer risk after mutually adjusting for all other markers. Sero-positivity to both Omp and HP 0305 was associated with an over 4-fold increase in gastric cancer incidence (OR, 4.09; 95% CI 3.26-5.13). When limited to only those who are CagA+ H. pylori+, Omp/HP 0305 sero-positivity remained strongly associated with an over 3-fold increase in the odds of gastric cancer (OR, 3.34; 95% CI 2.27-4.91). The results were highly consistent among the cohorts. CONCLUSIONS: We have confirmed new H. pylori biomarkers that are strongly associated with gastric cancer risk, even among those infected with the known H. pylori virulence factor CagA. These results may help to design cost-efficient prevention strategies to reduce gastric cancer incidence in East Asia.

Effect of obesity on the association between MYL2 (rs3782889) and high-density lipoprotein cholesterol among Korean men.

High-density lipoprotein (HDL) cholesterol levels are associated with a decreased risk of coronary artery disease. Several genome-wide association studies that have examined HDL cholesterol levels have implicated myosin light chain 2 regulatory cardiac slow (MYL2) as a possible causal factor. Herein, the association between the rs3782889 single-nucleotide polymorphism (SNP) in the MYL2 gene and HDL cholesterol levels was tested in the Korean population. A total of 4294 individuals were included in a replication study with MYL2 SNP rs3782889. SNP rs3782889 in the MYL2 gene was associated with mean HDL cholesterol level (effect per allele, -1.055 mg dl(-1), P=0.0005). Subjects with the CT/CC genotype had a 1.43-fold (range 1.19-1.73-fold) higher risk of an abnormal HDL cholesterol level (<40 mg dl(-1)) than subjects with the TT genotype. When analyzed by sex, the MYL2 association was stronger in men than that in women. When analyzed by body mass index (BMI), the MYL2 association was much stronger in male subjects with BMI ⩾26.44 kg m(-2) (odds ratio (OR)=2.68; 95% confidence interval (CI)=1.87-3.84; P<0.0001) than that in male subjects with BMI <26.44 kg m(-2). When compared with subjects having the TT genotype and BMI <26.44 kg m(-2), ORs (95% CI) were 3.30 (2.41-4.50) in subjects having the CT/CC genotype and BMI ⩾26.44 kg m(-2) (P for interaction <0.0001). Our results clearly demonstrate that genetic variants in MYL2 influence HDL cholesterol levels in Korean obese male subjects.

Longitudinal course of insomnia: age-related differences in subjective sleepiness and vigilance performance in a population-based sample.

OBJECTIVE: The present study utilized a population-based sample investigating the following aims: (1) compare the longitudinal course of insomnia in middle-aged and older adults and (2) examine age-related differences on subjective complaint and objective performance in middle-aged and older adults based on the course of insomnia. METHODS: 1657 middle-aged adults (48.16% male, mean age=55.35±4.03years) and 405 older adults (48.40% male, mean age=70.13±3.88years) from the Korean Genome and Epidemiology Study (KoGES) were classified into 4 groups - no insomnia (NI), single episode insomnia (SEI), remitted persistent insomnia (PI-R), and ongoing persistent insomnia (PI-O) based on their course of insomnia over 5 time points spaced two years apart. Their performance on the psychomotor vigilance task (PVT) and subjective daytime sleepiness were compared across different insomnia groups, and the results were compared between middle-aged adults and older adults. RESULTS: Analysis of covariance indicated that subjective daytime sleepiness was significantly different across the insomnia groups in middle-aged adults based on insomnia group (P=<.0001), but, did not affect objective vigilance performance. In contrast, older adults displayed significantly different PVT response time, but not daytime sleepiness, based on insomnia group (P=0.03). CONCLUSION: Insomnia impacts psychomotor performance and subjective sleepiness differently, based on age group. There may be underlying processes associated with the aging that amplifies the impact of insomnia on vigilance performance, yet lessens perceived sleepiness in older adults.

Obstructive sleep apnea as a risk factor for cerebral white matter change in a middle-aged and older general population.

STUDY OBJECTIVE: Obstructive sleep apnea (OSA) contributes to the development of systemic hypertension, and hypertension strongly predicts the development of white matter change (WMC). Thus, it is plausible that OSA mediates WMC. The goal of the current study is to determine whether a contextual relationship exists between OSA and cerebral WMC. DESIGN: Cross-sectional analyses conducted in a population-based study. SETTING: Korean community-based sample from the Korean Genome and Epidemiology Study (KoGES) who attended examinations in 2011 at a medical center. PARTICIPANTS: There were 503 individuals (mean ± SD, age 59.63 ± 7.48 y) who were free of previously diagnosed cardiovascular and neurologic diseases. MEASUREMENTS AND RESULTS: Participants underwent 1-night polysomnography and were classified as no OSA (obstructive apnea-hypopnea index [AHI] < 5, n = 289), mild OSA (AHI 5-15, n = 161), and moderate to severe OSA (AHI ≥ 15, n = 53). WMC was identified with brain magnetic resonance imaging (MRI) and was found in 199 individuals (39.56%). Multivariate logistic regression analyses adjusted for covariates revealed that moderate to severe OSA was significantly associated with the presence of WMC (odds ratio [OR] 2.08, 95%, confidence interval [CI] 1.05-4.13) compared with no OSA. Additional adjustment of hypertension to the model did not alter the significance of the association (OR 2.03, 95% CI 1.02-4.05). CONCLUSIONS: Moderate to severe OSA is an independent risk factor for WMC in middle-aged and older individuals. Thus, early recognition and treatment of OSA could reduce the risk of stroke and vascular dementia.

Testing bidirectional relationships between marital quality and sleep disturbances: a 4-year follow-up study in a Korean cohort.

OBJECTIVE: Both poor marital quality and sleep disturbances are risk factors for a broad range of mental and physical health morbidities. The purpose of the study was to investigate bidirectional relationships between marital quality and sleep disturbance and the moderating effects of age and gender. METHODS: Data from 1081 married individuals who participated in the Korean Genome and Epidemiology Study were analyzed. A marital quality questionnaire and the Pittsburgh Sleep Quality Index were used to assess marital quality and sleep disturbances at baseline and 4-year follow-up. Relevant covariates including sociodemographics, health status, health behaviors, and depressive symptoms were also measured. RESULTS: Hierarchical multiple regression models revealed that there was a significant interaction between marital quality and age predicting sleep disturbance (P=.017). While there was no association between marital quality and sleep disturbances for the younger group (ages 45-54; n=680), persons with lower marital quality were more likely to have greater sleep disturbances 4 years later for the older group (ages 55-74; n=401). By contrast, sleep disturbance was a significant predictor of marital quality 4 years later, regardless of age or gender (P=.025). CONCLUSION: Poor marital quality is a risk factor for sleep disturbance for older adults but not for middle-aged individuals. In turn, sleep disturbance may lead to lower marital quality for all age groups. Clinicians should be aware of the bidirectional relationships between marital and sleep problems for more effective treatments for both.

Longitudinal course of depression scores with and without insomnia in non-depressed individuals: a 6-year follow-up longitudinal study in a Korean cohort.

STUDY OBJECTIVE: This is a population-based longitudinal study that followed insomnia symptoms over a 6-year period in non-depressed individuals. The purpose of the study was to (1) investigate the longitudinal course of depression based on number of insomnia episodes; and (2) describe longitudinal associations between insomnia and depression, and insomnia and suicidal ideation. DESIGN: Population-based longitudinal study. SETTING: Community-based sample from the Korean Genome and Epidemiology Study (KoGES). PARTICIPANTS: 1,282 non-depressed individuals (44% male, mean age 52.3 ± 7.14 years). MEASUREMENTS AND RESULTS: This study prospectively assessed insomnia, depression, and suicidal ideation with 4 time points. Individuals were classified into no insomnia (NI), single episode insomnia (SEI), and persistent insomnia (PI; ≥ insomnia at 2+ time points) groups based on number of times insomnia was indicated. Mixed effects modeling indicated that depression scores increased significantly faster in the PI group compared to the NI (P < 0.001) and SEI (P = 0.02) groups. Additionally, the PI group had significantly increased odds of depression as compared to NI or SEI (OR 2.44, P = 0.001) groups, with 18.7% meeting criteria for depression compared to the NI (5.3%) and SEI (11.6%) groups at end point. The PI group also had significantly increased odds of suicidal ideation as compared to NI or SEI (OR 1.86, P = 0.002) groups. CONCLUSIONS: Persistent insomnia significantly increases the rate in which depression occurs over time in non-depressed individuals, which ultimately leads to higher risk for depression. Additionally, having persistent insomnia also increased the risk of suicidal ideation. CITATION: Suh S; Kim H; Yang HC; Cho ER; Lee SK; Shin C. Longitudinal course of depression scores with and without insomnia in non-depressed individuals: a 6-year follow-up longitudinal study in a Korean cohort. SLEEP 2013;36(3):369-376.

Obstructive sleep apnea as a risk factor for silent cerebral infarction.

Previous studies have suggested that obstructive sleep apnea (OSA) may be a risk factor for stroke. In this study, we assessed that OSA is an independent risk factor of silent cerebral infarction (SCI) in the general population, and in a non-obese population. This study recruited a total of 746 participants (252 men and 494 women) aged 50-79 years as part of the Korean Genome and Epidemiology Study (KoGES); they underwent polysomnography, brain magnetic resonance imaging and health screening examinations. SCI was assessed by subtypes and brain regions, and lacunar infarction represented lesions <15 mm in size in the penetrating arteries. Moderate-severe OSA was determined by apnea-hypopnea index ≥15. The results indicated that 12.06% had moderate-severe OSA, 7.64% of participants had SCI and 4.96% had lacunar infarction. Moderate-severe OSA was associated positively with SCI [odds ratio (OR): 2.44, 95% confidence interval (CI): 1.03-5.80] and lacunar infarction (OR: 3.48, 95% CI: 1.31-9.23) in the age ≥65-year group compared with those with non-OSA. Additionally, in the basal ganglia, OSA was associated with an increase in the odds for SCI and lacunar infarction in all age groups, and especially in the ≥65-year age group. In the non-obese participants, OSA was also associated positively with SCI in the ≥65-year age group, lacunar infarction in all age groups, and especially in the ≥65-year age group. There was also a positive association with the basal ganglia. Moderate-severe OSA was associated positively with SCI and lacunar infarction in elderly participants. Treatment of OSA may reduce new first-time cerebrovascular events and recurrences.

Dietary patterns and their associations with health behaviours in Korea.

OBJECTIVE: Dietary habits, including dietary patterns, have been associated with the risk of chronic diseases, including cancer. The objective of the present study was to evaluate Korean dietary patterns as assessed by using an FFQ and associations of dietary patterns with lifestyle risk factors. DESIGN: Dietary patterns were analysed by factor analysis using a sixteen-group FFQ. The associations between dietary patterns and lifestyle risk factors were investigated by logistic regression analysis. SETTING: The National Cancer Center in South Korea. SUBJECTS: The study population included 11 440 participants aged ≥ 30 years who were recruited between 2002 and 2007. RESULTS: Compared with the lowest quartile intake of each dietary pattern, current smoking was positively associated with the Western pattern (OR = 1·55 for the highest quartile, 95 % CI 1·27, 1·88; P < 0·001) and the traditional pattern (OR = 1·34, 95 % CI 1·11, 1·62; P = 0·002) in men, but was inversely associated with the healthy pattern in both genders (P < 0·001) and the traditional pattern (OR = 0·52, 95 % CI 0·36, 0·75; P = 0·001) in women. Alcohol consumption was positively associated with all patterns in both genders, while no association was observed with the healthy pattern in women. Physical activity and dietary supplement use were positively associated with all patterns in both genders, with the exception of physical activity in women, which showed an inverse association with the traditional pattern. CONCLUSIONS: Dietary patterns are strongly associated with health behaviours. The possible confounding effect of other risk behaviours should be appropriately considered when conducting nutritional epidemiological studies.

Factors associated with use of ultrasonography screening for hepatocellular carcinoma among hepatitis B or C carriers.

OBJECTIVES: Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are important risk factors for hepatocellular carcinoma (HCC). Yet, there have been few studies on adherence to screening recommendations for groups at high risk for HCC. We assessed whether demographic factors or medical conditions affected screening participation among HBV/HCV carriers. METHODS: The study population consisted of 15565 men and women who visited the National Cancer Center, Korea between August 2002 and July 2009. A self-administered questionnaire was used to collect information on demographic characteristics, medical history, including chronic HBV and HCV infection, and health check-up history. HBV surface antigen and HCV antibody levels were measured in serum. RESULTS: Among 781 HBV carriers, 596 (76.3%) were aware of their infection and 451 (57.8%) had ever been tested by ultrasonography. Among HCV carriers, 49 of 127 (36.6%) were aware of their infection and 61 (48.0%) had ever been tested by ultrasonography. Among HBV carriers, male sex (OR, 1.68; 95% CI, 1.22-2.31), family history of liver disease (OR, 2.04; 95% CI, 1.43-2.90), medical history of hyperlipidemia (OR, 2.70; 95% CI, 1.36-5.33), and awareness of infection status (OR, 4.30; 95% CI, 2.99-6.17) were associated with being tested. Among HCV carriers, awareness of infection (OR, 3.77; 95% CI, 1.72-8.26) was significantly associated with being tested by ultrasonography. CONCLUSION: Male sex, family history of liver disease, medical history of hyperlipidemia, and awareness of high risk status were associated with being tested by ultrasonography.

Hepatitis B virus infection and risk of non-Hodgkin lymphoma in South Korea: a cohort study.

BACKGROUND: Hepatitis B virus (HBV) infection is common throughout Asia and Africa. Whether chronic HBV infection increases risk of non-Hodgkin lymphoma (NHL) is unclear. We aimed to assess the association between chronic HBV infection and subsequent development of NHL in a South Korean cohort. METHODS: The Korean Cancer Prevention Study is a cohort study of South Korean workers and their dependants enrolled during 1992-95. From this cohort, we excluded individuals who died before Jan 1, 1993, who had cancer at or before the initial visit, who had missing information about weight, height, alanine aminotransferase or aspartate aminotransferase concentrations, or alcohol use, or who had evidence of HIV or HCV infection. Of 1,284,586 eligible participants, 603,585 had baseline data for serum hepatitis B surface antigen (HBsAg) status and were included in our study. We regarded HBsAg positivity at baseline as evidence of chronic HBV infection. Participants were followed up from baseline until Dec 31, 2006. We used national databases of inpatient and outpatient diagnoses and mortality records to ascertain occurrence of haematological malignancies. We assessed incidence of NHL overall and of NHL subtypes, malignant immunoproliferation, Hodgkin's lymphoma, multiple myeloma, and various leukaemias. We used Cox regression to evaluate associations with HBsAg status, adjusting for sex, age, and enrolment year. FINDINGS: 53,045 (9%) of 603,585 participants tested positive for HBsAg at baseline. Subsequently, 133 HBsAg-positive and 905 HBsAg-negative individuals developed NHL. HBsAg-positive participants had an increased risk of NHL overall compared with those who were HBsAg-negative (incidence 19.4 vs 12.3 per 100,000 person-years; hazard ratio [HR] 1.74, 95% CI 1.45-2.09, adjusted for sex, age at baseline, and enrolment year). Among NHL subtypes, HBsAg positivity was associated with increased risk of diffuse large B-cell lymphoma (n=325, incidence 6.86 vs 3.79 per 100,000 person-years; adjusted HR 2.01, 1.48-2.75) and other or unknown subtypes (n=591, incidence 10.5 vs 7.07 per 100,000 person-years; adjusted HR 1.65, 1.29-2.11), compared with HBsAg negativity. Increased risk was also recorded for malignant immunoproliferation (n=14, incidence 0.44 vs 0.15 per 100,000 person-years; adjusted HR 3.79, 1.05-13.7). Risk of these malignancies was consistently raised in HBsAg-positive participants throughout 14 years of follow-up. HBsAg positivity was not associated with follicular or T-cell NHL, Hodgkin's lymphoma, multiple myeloma, or various leukaemias. INTERPRETATION: During extended follow-up, HBsAg-positive individuals had an increased risk of NHL, suggesting that chronic HBV infection promotes lymphomagenesis. FUNDING: Korean Seoul City Research and the National Research and Development Program for Cancer Control, Ministry for Health, Welfare and Family Affairs, Republic of Korea; US National Cancer Institute.

Leisure-time physical activity is associated with a reduced risk for metabolic syndrome.

PURPOSE: The objective of this study was to evaluate the cross-sectional relationship between leisure-time physical activity and the prevalence of metabolic syndrome in the Korean population. METHODS: The study population included 11,925 participants (6,878 men and 5,047 women), aged 30-79 years. Metabolic syndrome was defined based on the National Cholesterol Education Program criteria of having three or more cardiovascular risk factors, with a modified obesity index. Self-reported leisure-time physical activity was calculated using metabolic equivalents (MET) scores. Logistic regression was used to estimate the association between leisure-time physical activity and the prevalence of metabolic syndrome, with adjustment for other risk factors. RESULTS: The prevalence of metabolic syndrome was 18.2% in men and 8.5% in women. After adjustments for age and education levels, household income, smoking status, and alcohol consumption, the prevalence of metabolic syndrome among participants in the middle and top tertiles of leisure-time physical activity was significantly lower than that among those with no physical activity; the odds ratios (95% confidence intervals) were 0.84 (0.71-0.99) and 0.75 (0.62-0.89), respectively, in men and 0.54 (0.39-0.76) and 0.65 (0.48-0.88), respectively, in women. CONCLUSIONS: These results suggest that increasing levels of leisure-time physical activity, in terms of duration or intensity, are linearly associated with a reduced risk for metabolic syndrome.

Factors associated with awareness of infection status among chronic hepatitis B and C carriers in Korea.

Hepatitis B (HBV) and hepatitis C (HCV) viral infections are the most important risk factors for hepatocellular carcinoma (HCC), which is responsible for 17.5% of cancer deaths in Korea. The objectives of this study were to identify demographic characteristics that may affect hepatitis carriers' awareness of their infection status, and to assess whether health-related behaviors differed by awareness of the infection. Among 18,636 persons who were recruited from a cancer screenee cohort, 904 were HBV carriers and 146 were HCV carriers. Among the HBV carriers, 74.2% were aware of their infection status. Higher education (odds ratio, 1.8; college versus middle school or less), family history of liver cancer or disease, and marriage were associated with awareness of HBV infection status. Participants who were aware of their HBV carrier status were more likely to be former smokers or drinkers than those who were not aware of their status. Only 34.9% of HCV carriers were aware of their HCV infection status. No demographic characteristics were related to awareness of HCV infection status among HCV carriers. However, HCV carriers who were aware of their infection status were more likely to be former drinkers (odds ratio, 9.2; 95% confidence interval, 1.8-47.2). In conclusion, two thirds of HCV carriers and one fourth of HBV carriers in this study population were not aware of their infection status, and awareness of hepatitis infection status was significantly associated with other risk behaviors, such as alcohol consumption and cigarette smoking.

Body mass index and cancer risk in Korean men and women.

Obesity is associated with diverse health risks, but the role of body weight (BMI) as a risk factor for all and site-specific cancers remains controversial and risks for cancer associated with obesity have not been well-characterized in Asians. Body weight and risk for cancer were examined in a 14-year prospective cohort study of 1,213,829 Koreans aged 30-95 years insured by the National Health Insurance Corporation who had a biennial medical evaluation in 1992-1995. Incidence rates for all cancers and site-specific cancers were examined in relation to BMI. Age- and smoking-status adjusted hazard ratios (HR) with 95% confidence intervals (CI) were examined using the Cox proportional hazards model. For both sexes, the average baseline BMI was 23.2 kg/m(2), and the association of risk for all-cancers with BMI was positive. Obese men (BMI >or= 30 kg/m(2)) were at increased risk for developing the following cancers: stomach (1.31, 1.05-1.64), colon (1.42, 1.02-1.98), liver (1.63, 1.27-2.10) and gallbladder (1.65, 1.11-2.44). Obese women (BMI >or= 30 kg/m(2)) were at increased risk for developing liver cancer (1.39, 1.00-1.94), pancreatic cancer (1.80, 1.14-2.86) and breast cancer among women aged >or=50 years old (1.38, 1.00-1.90). The HRs were comparable in never and ever smokers for all cancers and all specific sites except for lung cancer. For all cancers common to both sexes, the association was significantly weaker (p < 0.01) in females. Our study provides further confirmation of the excess cancer risk associated with obesity. Rising obesity in Asian populations raises concern that increasing numbers of avoidable cancer cases will occur among Asians.