In this era of chronic diseases, large studies are essential in investigating genes, environment, and gene–environment interactions as disease causes, particularly when associations are important but not strong. Moreover, to allow expansion and generalization of the results, studies should be conducted in populations outside Western countries. Here, we briefly describe the Asia Cohort Consortium (ACC), a collaborative cancer cohort research project that was first proposed in 2004 and now involves more than 1 million healthy individuals across Asia. There are approximately 50 active members from Bangladesh, China, India, Japan, Korea, Malaysia, Singapore, Taiwan, Thailand, the United States, and elsewhere. To date, the work of the ACC includes 3 articles published in 2011 on the roles of body mass index, tobacco smoking, and alcohol consumption in mortality, diabetes, and cancer of the small intestine. Many challenges remain, including data harmonization, resolution of ethical and legal issues, establishment of protocols for biologic samples and transfer agreements, and funding procurement.

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Social epidemiology is the field of study that attempts to understand the social determinants of health and the dynamics between societal settings and health. In the past 3 decades, large-scale studies in the West have accumulated a range of measures and methodologies to pursue this goal. We would like to suggest that there may be conceptual gaps in the science if Western research models are applied uncritically in East Asian studies of socioeconomic, gender, and ethnic inequalities in health. On one hand, there are common concerns, including population aging and gendered labor market participation. Further, international comparison must be built on shared concepts such as socioeconomic stratification in market economies. On the other hand, some aspects of health, such as common mental disorders, may have culturally specific manifestations that require development of perspectives (and perhaps novel measures) in order to reveal Eastern specifics. Exploring and debating commonalities and differences in the determinants of health in Oriental and Occidental cultures could offer fresh inspiration and insight for the next phase of social epidemiology in both regions.

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Background: Although associations between snoring and cardiovascular disease have been reported in several prospective studies, there is limited evidence from Asian populations. The objective of this study was to determine if there is an association between self-reported snoring frequency and the incidence of cardiovascular disease in Japanese.
Methods: The subjects were 2350 men and 4163 women aged 40 to 69 years who lived in 3 communities in Japan. All subjects were participants in the Circulatory Risk in Communities Study (CIRCS) and were followed for 6 years. Incidence of cardiovascular disease during the follow-up period comprised events of myocardial infarction, angina pectoris, sudden cardiac death and stroke.
Results: During the 6-year follow-up period, 97 participants (56 men and 41 women) had cardiovascular events. After adjustment for potential confounding factors, self-reported snoring frequency was associated with an increased risk of cardiovascular events among women but not men. The hazard ratios (95% CI) for cardiovascular events were 0.9 (0.4–2.0) for sometimes snoring and 2.5 (1.0–6.1) for everyday snoring in women and 0.7 (0.3–1.3) and 1.0 (0.5–2.1), respectively, in men. Further adjustment for body mass index attenuated the association in women; the respective hazard ratios for cardiovascular events were 0.9 (0.4–1.9) and 2.1 (0.9–5.4).
Conclusions: Self-reported habitual snoring was associated with increased risk of cardiovascular events among Japanese women. Overweight may partly mediate this association.

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Background: We examined trends in chronic obstructive pulmonary disease (COPD) mortality in Japan.
Methods: An age-period-cohort model was used to examine trends in COPD mortality by age, time period, and birth cohort among adults aged 40 years or older from 1950 to 2004.
Results: During the study period, the age-standardized rate of COPD mortality substantially decreased from 71.3 per 100 000 to 19.7 in men and from 41.7 to 4.3 in women. The period effects rapidly declined during the early period in both sexes. They have increased in recent years in men but have continued to decrease in women. The cohort effects began increasing in the 1865–1869 birth cohort, peaked in the 1880–1889 cohort, and decreased thereafter among the recent cohorts.
Conclusions: An early decrease in the period effects might have been associated with changes in disease structure and misclassification of COPD in the early period. Changes in cohort effects might have been mostly associated with changes in cigarette consumption and smoking prevalence in the Japanese population. Changes in those effects may also be a proxy for other social changes over time.

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Background: Although the amount of detail in informed consent documents has increased over time and the documents have therefore become very long, there is little research on whether longer informed consent documents actually result in (1) better informed research subjects or (2) higher consent rates. We therefore conducted an add-on randomized controlled trial to the Takashima Study, a prospective Japanese population-based genetic cohort study, to test the hypothesis that a shorter informed consent form would satisfy both of the above goals.
Methods: Standard (10 459 words, 11 pages) and short (3602 words, 5 pages) consent forms in Japanese were developed and distributed using cluster-randomization to 293 potential cohort subjects living in 9 medico-social units and 288 subjects in 8 medico-social units, respectively.
Results: Few differences were found between the 2 groups with regard to outcome measures, including participants’ self-perceived understanding, recall of information, concerns, voluntariness, trust, satisfaction, sense of duty, and consent rates.
Conclusions: A short informed consent form was no less valid than a standard form with regard to fulfilling ethical requirements and securing the scientific validity of research.

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Background: Obesity is closely associated with chronic diseases such as hypertension, type 2 diabetes mellitus (T2DM), and dyslipidemia. We analyzed the optimal obesity index cut-off values for metabolic syndrome (MetS), and identified the obesity index that is more closely associated with these chronic diseases, in a population of northern Chinese.
Methods: We surveyed 8940 adults (age, 20–74 years) living in northern China for chronic diseases. Receiver operating characteristics (ROC) analysis, relative risk, and multivariate regression were used to develop an appropriate index and optimal cut-off values for MetS and obesity-related chronic diseases.
Results: Waist circumference (WC) and body mass index (BMI) were good markers for MetS, WC was a good marker for T2DM and dyslipidemia, and BMI was a good marker for hypertension. The optimal BMI cut-off value of MetS was 24 kg/m², and the optimal WC cut-offs were 86 cm and 78 cm in men and women, respectively. Relative risk regression models showed that BMI was associated with hypertension, T2DM, and hypertriglyceridemia and a higher prevalence ratio (PR) for hypertension: 2.35 (95% CI, 2.18–2.50). WC was associated with T2DM, hypertension, and hypertriglyceridemia, with PRs of 2.05 (1.63–2.55) for T2DM and 2.47 (2.04–2.85) for hypertriglyceridemia. In multivariate regression models, the standardized regression coefficients (SRCs) of BMI were greater for SBP and DBP, and the SRC of WC was greater for fasting blood glucose, 2-hour postload blood glucose, triglyceride, and total cholesterol.
Conclusions: Our analysis of a population of northern Chinese indicates that the optimal cut-off values for MetS are WCs of 86 cm in men and 78 cm in women and a BMI of 24 kg/m² in both sexes. BMI was strongly associated with hypertension, while WC was strongly associated with T2DM and dyslipidemia.

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Background: Analysis of the effects of social gradients on women’s health requires a suitable means of assessing social standing.
Methods: We compared social gradients in stroke risk among 9317 married Japanese women from the Japan Public Health Center-based Prospective Study over a 16-year period. Social gradient was estimated by 3 methods of indicating social position: education level derived by using the individual approach (woman’s own educational level), the conventional approach (using her partner’s educational level), and the combined approach (combining the woman’s and her partner’s educational levels).
Results: As compared with the lowest educational group, stroke risk was similar among women in the highest educational group using the individual approach and lower, but not significantly so, with the conventional approach. With the combined approach, however, the age- and area-adjusted hazard ratio (HR) was significantly lower among the highest education group as compared with the lowest group (HR = 0.52, 95% CI: 0.36, 0.76), and the relative index of inequality was significant (RII = 0.48, 95% CI: 0.32, 0.72). Using the combined approach, the results were similar irrespective of employment status. In the combined highest educational group, stroke risk among unemployed women was significantly reduced by 54%, while stroke risk for employed women was significantly reduced by 46%, as compared with the lowest educational group, with RIIs of 0.42 (95% CI: 0.21, 0.85) and 0.49 (0.30, 0.80), respectively.
Conclusions: The results suggest that a combined approach better reflects social standing among married women in Japan.

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Background: We assessed the impact of parental history of stroke on stroke mortality, as well as the effect modification between lifestyle and stroke mortality, among Japanese.
Methods: In this community-based, prospective cohort study, 22 763 men and 30 928 women aged 40 to 79 years with no history of cardiovascular disease or cancer at baseline (1988–1990) were followed through 2008. We examined the association between parental history of stroke and stroke mortality and estimated the impact of the combination of lifestyle and parental history on stroke mortality in offspring.
Results: During a mean follow-up period of 15.9 years, there were 1502 stroke deaths. In both sexes, participants with a parental history of stroke had a higher risk of stroke mortality as compared with those without such a history. The respective multivariable hazard ratio (95% CI) and population attributable fraction were 1.28 (1.10–1.49) and 5.4% in men, 1.22 (1.04–1.43) and 4.3% in women, and 1.25 (1.12–1.40) and 4.8% in all participants, for offspring with a maternal and/or paternal history of stroke. There was an inverse association between healthy-lifestyle score and stroke mortality, irrespective of parental history of stroke. The overall multivariable hazard ratio for the highest (6–8) versus the lowest (0–3) score categories was 0.56 (95% CI, 0.43–0.72) for participants with a maternal and/or paternal history of stroke and 0.44 (0.36–0.53) for those without such a history.
Conclusions: Parental history of stroke was associated with stroke mortality in offspring. The inverse association between healthy lifestyle behaviors and stroke mortality, regardless of parental history, suggests that lifestyle modification is beneficial, even among individuals with a parental history of stroke.

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Background: The proportion of Japanese adults aged 65 years or older is predicted to increase; thus, it is becoming more important to identify factors that influence health status among elderly adults in Japan. We conducted a follow-up study of community-dwelling elderly adults to assess the relationship of hobby activities with mortality and incident frailty.
Methods: We randomly selected 3583 individuals aged 65 to 84 years from the residential registries of 7 study areas in Hokkaido, Japan in August 2007. Among them, 1955 (54.6%) returned completed questionnaires with written informed consent by mail. The baseline assessment questionnaire comprised questions on current and past involvement in hobby activities, self-perceived health status, smoking and drinking habits, and body height and weight. Questions on hobby activities were from 4 categories: solitary physical, group physical, solitary cultural, and group cultural activities. We later conducted a follow-up survey of the participants to ascertain all-cause mortality and incident frailty. A Cox proportional hazards model was used for analysis of data from September 2007 to May 2010.
Results: After adjusting for potential confounders, the risk of incident frailty among respondents participating in solitary physical activities was significantly lower than in those who did not participate in such activities (hazard ratio = 0.57; 95% CI 0.33, 0.99). Furthermore, the risk of incident frailty among respondents taking part in group cultural activities was significantly lower than in those who did not participate in such activities (0.41; 0.19, 0.87).
Conclusions: These findings may be important for programs that seek to promote good health among elderly adults.

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Background: We assessed the relationship between height and coronary heart disease (CHD) in an urban population of Tehran.
Methods: 4110 participants of the Tehran Lipid and Glucose Study who were 40 years of age or older (1880 men and 2230 women; mean age, 55.1 and 53.0 years, respectively) and free of CHD at baseline were followed for a mean of 9.1 years. We used Cox proportional hazards regression to evaluate the risk of a first CHD event across height tertiles.
Results: First CHD events occurred in 239 men and 172 women. The estimated crude HR (95% CI) for CHD events associated with an increment of 1 SD in height was 0.96 (0.28–3.33) in men and 0.84 (0.72–0.97) in women. After adjustment for age, the associations were no longer present. Further adjustment for other confounders had little impact on the results: the HR (95% CI) associated with an increase of 1 SD in height was 1.02 (0.87–1.20) in men and 0.82 (0.66–1.02) in women.
Conclusions: After adjustment for age, height was not associated with CHD incidence in men or women.

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Background: We linked viral titers and respiratory symptom scores for seasonal influenza to estimate the effective contact rate among schoolchildren.
Methods: We analyzed 274 diary-based questionnaires. In addition, 2 sets of influenza data from published studies were used to investigate the relationship between viral titer, total symptom score, and normalized contact rate in children.
Results: The mean number (SD) of contacts for children in grades 7 to 9 ranged from 9.44 ± 8.68 to 11.18 ± 7.98 person⁻¹ day⁻¹; contact behavior was similar across school grades. The mean number of contacts was 5.66 ± 6.23 person⁻¹ day⁻¹ (range, 0 to 44 person⁻¹ day⁻¹) for the age group of 13 to 19 years. Estimated contact age, household size, contact duration, and contact frequency were the variables most strongly associated with total number of contacts. We also found that a reduction in total respiratory symptom scores among infected individuals had a positive correlation with an increase in the normalized contact rate.
Conclusions: The relationship between daily virus titer and respiratory symptom score can be used to estimate the effective contact rate in explaining the spread of an airborne transmissible disease. The present findings can be incorporated into population-dynamic models of influenza transmission among schoolchildren.

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Background: We examined the association between parity and risk of lung cancer.
Methods: The study cohort consisted of all women with a record of a first singleton birth in the Taiwanese Birth Register between 1978 and 1987. We tracked each woman from the time of their first childbirth to 31 December 2009. Follow-up was terminated when the mother died, when she reached age 50 years, or on 31 December 2009, whichever occurred first. The vital status of mothers was ascertained by linking records with the computerized mortality database. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) for death from lung cancer associated with parity.
Results: There were 1375 lung cancer deaths during 32 243 637.08 person-years of follow-up. The mortality rate of lung cancer was 4.26 cases per 100 000 person-years. As compared with women who had given birth to only 1 child, the adjusted HR was 1.13 (95% CI, 0.94–1.35) for women who had 2 children, 1.10 (0.91–1.33) for those who had 3 children, and 1.22 (0.96–1.54) for those who had 4 or more children.
Conclusions: The findings suggest that premenopausal women of higher parity tended to have an increased risk of lung cancer, although the trend was not statistically significant.

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Background: Fabry disease (FD) is a rare X-linked lysosomal storage disorder and is included in the Specified Disease Treatment Research Program in Japan, which subsidizes medical care for beneficiaries with rare and other, designated diseases. However, no report on the epidemiologic features of Fabry disease has been published in Japan.
Methods: We used clinical research data reports submitted to the program between 2003 and 2008 to assess the epidemiologic features of 315 beneficiaries with FD.
Results: Of the 315 program beneficiaries, 198 were men (mean age, 37.4 years) and 117 were women (mean age, 51.2 years). The overall incidence in Japan was 0.25 cases per 100 000 individuals, and prevalence among men was 1.78 times that among women. More than 80% of beneficiaries were capable of working, going to school, or doing housework; however, 46 beneficiaries (14.6%) required home care, and 9 (2.9%) were living in hospitals or other medical facilities. As compared with the previous year, the clinical course of FD at beneficiary registration was unchanged for 178 of 290 beneficiaries (61.4%), worse for 81 (27.9%), and improved or cured for 31 (10.7%). The distribution of beneficiary-related characteristics was similar between men and women, and no significant difference was observed.
Conclusions: The high percentage (>80%) of individuals with FD who were able to work, attend school, and perform tasks such as housework could reflect an improvement in the clinical course of FD after enzyme replacement therapy. We must continue data collection and conduct further studies to improve our understanding of the descriptive epidemiology of FD.

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