It has been suggested that soy isoflavones have protective effects against breast cancer. However, data from epidemiological studies are not conclusive. A recent meta-analysis showed that soy intake was inversely associated with breast cancer risk in Asian but not Western populations, which indicates that protection against breast cancer may require that women consume levels of soy typical in Asian diets. In addition to the amount of soy isoflavones consumed, the form and food source of isoflavones, timing of isoflavone exposure, estrogen receptor status of tumors, and equol-producer status and hormonal profile of individuals may modify the association between soy isoflavone intake and the risk of breast cancer. These factors might explain the heterogeneity of results from studies. This present report contrasts background data from Japanese and Western women to identify the potential modifying of these factors.

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In Japan, cancer has long been recognized as a major component of the overall pattern of disease. Currently, there is a need to implement practical control measures with specific numerical targets appropriate for the Japanese population. Using data from the Japan Public Health Center-based Prospective Study, the author estimated the impact of major risk factors on overall cancer risk among a Japanese population. These risk factors included tobacco smoking, alcohol drinking, body mass index, history of diabetes, physical activity, and metabolic factors and their aggregates. The results show that tobacco smoking and heavy alcohol drinking were significantly positively associated with overall cancer risk, and that total physical activity was significantly inversely associated with the risk of cancer. Although people with a history of diabetes may be at increased risk of cancer, extreme body mass index and metabolic factors in the aggregate had little impact on overall cancer risk in the Japanese population.

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Background: Appendicitis is one of the most frequent acute surgical conditions of the abdomen, and appendectomy is one of the most commonly performed operations in the world. However, epidemiological data on appendicitis have not been reported for South Korean or East Asian populations.
Methods: We analyzed the epidemiological features and lifetime risk of appendicitis and appendectomy in South Korea using data collected for the national health insurance database from 2005 through 2007.
Results: Appendectomy was performed in 59.70% of inpatients diagnosed with appendicitis. The overall incidences of appendicitis, total appendectomy, and perforated appendectomy were 22.71, 13.56, and 2.91 per 10 000 population per year, respectively. The incidence of appendicitis and appendectomy showed clear seasonality, with a peak in summer. The standardized lifetime risks of appendicitis and appendectomy were constant from 2005 through 2007. A life table model suggests that the lifetime risk of appendicitis is 16.33% for males and 16.34% for females, and that the lifetime risk of appendectomy is 9.89% for males and 9.61% for females.
Conclusions: As compared to results obtained in research on Western populations, appendicitis and appendectomy had a similar perforation rate and seasonality, but a higher overall incidence, in South Koreans. Between 2005 and 2007, the incidence of appendicitis and appendectomy was constant. Overall, an estimated 15 incidental appendectomies are performed to prevent 1 inpatient with suspected appendicitis, and 26 incidental appendectomies are performed to prevent 1 appendectomy. Incidental appendectomy may have greater preventive value in Koreans.

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Background: Although sleep is one of the most important health-related factors, the relationship between sleep duration and the incidence of cardiovascular events has not been fully described.
Methods: The present study comprised the 11 367 study subjects (4413 men and 6954 women) of the Jichi Medical School Cohort Study, a population-based prospective study. Baseline data were obtained by questionnaire and health examinations between April 1992 and July 1995 in 12 rural areas in Japan, and the main outcome measures were the incidence of cardiovascular diseases (stroke and myocardial infarction [MI]). Cox proportional hazards models were used to analyze the association between sleep duration and the incidence of cardiovascular events.
Results: A total of 481carciovascular events (255 men and 226 women) were observed during an average follow-up period of 10.7 years. After adjusting for age, systolic blood pressure, serum total cholesterol, body mass index, smoking habits, and alcohol drinking habits, the hazard ratios (95% confidence intervals) for the incidence of cardiovascular diseases for individuals sleeping less than 6 hours and 9 hours or longer were 2.14 (1.11–4.13) and 1.33 (0.93–1.92) in men, and 1.46 (0.70–3.04) and 1.28 (0.88–1.87) in women, respectively, relative to those who reported sleeping 7 to 7.9 hours per day.
Conclusions: Our data indicate that men who sleep less than 6 hours a day have a higher risk of cardiovascular events than those sleeping 7 to 7.9 hours.

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Background: We attempted to apply the model of effort–reward imbalance (ERI) to school settings in order to measure students’ psychosocial stress and analyze its association with self-rated health in adolescents.
Methods: A cross-sectional survey was conducted in Kunming, China among 1004 Chinese students (468 boys and 536 girls) in grades 7 through 12, using a 19-item effort–reward imbalance questionnaire.
Results: Satisfactory internal consistencies for the scales for effort and reward were obtained; the value for the scale for overcommitment was acceptable. Factor analysis replicated the theoretical structure of the ERI construct in this sample of Chinese students. All 3 scales were associated with an elevated odds ratio for diminished self-rated health, and the effect was strongest for the effort–reward ratio, as predicted by the theory. Sex and grade differences were also observed.
Conclusions: The ERI questionnaire is a valid instrument for identifying sources of stressful experience, in terms of effort–reward imbalance, among adolescents in school settings.

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Background: The Standard Tables of Food Composition in Japan do not include information on trans fatty acids. Previous studies estimating trans fatty acid intake among Japanese have limitations regarding the databases utilized and diet assessment methodologies. We developed a comprehensive database of trans fatty acid food composition, and used this database to estimate intake among a Japanese population.
Methods: The database was developed using analytic values from the literature and nutrient analysis software encompassing foods in the US, as well as values estimated from recipes or nutrient compositions. We collected 16-day diet records from 225 adults aged 30 to 69 years living in 4 areas of Japan. Trans fatty acid intake was estimated based on the database and the 16-day diet records.
Results: Mean total fat and trans fatty acid intake was 56.9 g/day (27.7% total energy) and 1.7 g/day (0.8% total energy), respectively, for women and 66.8 g/day (25.5% total energy) and 1.7 g/day (0.7% total energy) for men. Trans fatty acid intake accounted for greater than 1% of total energy intake, which is the maximum recommended according to the World Health Organization, in 24.4% of women and 5.7% of men, and was particularly high among women living in urban areas and those aged 30–49 years. The largest contributors to trans fatty acid intake were confectionaries in women and fats and oils in men.
Conclusions: Although mean trans fatty acid intake was below the maximum recommended intake of the World Health Organization, intake among subgroups was of concern. Further public health efforts to reduce trans fatty acid intake should be encouraged.

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Background: Young age at onset of smoking is a known risk factor for cancer; however, few studies have investigated the risk of cancer associated with onset of smoking during adolescence in Japan.
Methods: We analyzed a portion of the data from a population-based cohort of 40 897 subjects aged 40 to 69 years with a history of smoking and no history of cancer at baseline.
Results: During a 14-year follow-up period, 4386 total cancers and 681 lung cancers were newly diagnosed. As compared with smokers who started smoking after the age of 20 years, those who started before the age of 17 years smoked a significantly larger number of cigarettes per day for a significantly longer duration; they also had a significantly higher risk of lung cancer. The hazard ratios in men and women were 1.48 (95% confidence interval, 1.11–1.96) and 8.07 (2.34–27.85), respectively. After further adjustment for smoking amount, the associations remained significant. There was a statistically significant inverse correlation between lung cancer risk and age at onset of smoking in male current smokers whose baseline age was 50 to 59 years; no such association was detected among other age strata.
Conclusions: There was no clear evidence of increased risk of cancer due to adolescent smoking. However, adolescent smoking appeared to indirectly increase lung cancer risk because it was associated with a longer duration and larger amount of smoking.

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Background: Although seasonal variation in stroke incidence has been reported, it is not known whether year-long exposure to particular meteorological conditions affects the risk of stroke independently of conventional cardiovascular risk factors.
Methods: We conducted a cohort study involving 4849 men and 7529 women residing in 12 communities dispersed throughout Japan. Baseline data were obtained from April 1992 through July 1995. Follow-up was conducted annually to capture first-ever-in-life stroke events. Weather information during the period was also obtained for each community. Multilevel logistic regression analysis was conducted to evaluate the association between stroke incidence and each meteorological parameter adjusted for age, obesity, smoking status, total cholesterol, systolic blood pressure, diabetes, and other meteorological parameters.
Results: Over an average of 10.7 years of follow-up, 229 men and 221 women had stroke events. Among women, high annual rainfall (OR per 1000 mm, 1.46; 95% confidence interval, 1.05–2.03), low average ambient temperature (OR per 1 °C, 0.79; 0.66–0.94), and number of cold days per year (OR per 10 days, 3.37; 1.43–7.97) were associated with increased risk of stroke incidence, independent of conventional risk factors. Among men, number of cold days (OR per 10 days, 1.07; 1.02–1.12) was associated with an increased risk of stroke incidence, but the association became nonsignificant after adjustment for other risk factors. Similar results were obtained for cerebral infarction and cerebral hemorrhage.
Conclusions: Long-term exposure to some meteorological conditions may affect the risk of stroke, particularly in women, independent of conventional risk factors.

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Background: Sleep pattern is an important factor in a child’s mental, behavioural and physical status. To evaluate the sleep patterns of children, subjective tools such as sleep logs and questionnaires are still widely used in addition to objective methods of sleep assessment. Despite the established correlation between subjective and objective sleep variables, the characteristic features of subjective assessment have not been elucidated.
Methods: To investigate the characteristics of parental sleep assessment (daily sleep log and brief questionnaire) in preschool children, a 7-day actigraphic sleep study was conducted in 48 healthy 5-year-old children.
Results: Sleep schedule variables in the parental reports generally correlated well with actigraphic assessment of sleep patterns; however, sleep periods were longer in parental reports than in actigraphic recordings. Although the daily sleep log was better correlated with actigraphy, the brief questionnaire showed a good correlation with sleep pattern on weekday actigraphic assessments. Parental reports recorded fewer than 10% of the night wakings recorded by actigraphy.
Conclusions: Subjective sleep assessments remain useful, although their utility depends on the purpose and size of the study in question. However, knowledge of the potential biases and characteristics of such assessments is essential for correct interpretation of the data.

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Objective: To examine the validity and reproducibility of food groups in the semi-quantitative food frequency questionnaire (FFQ) developed for the Tehran Lipid and Glucose Study (TLGS).
Methods: To evaluate the reproducibility of food groups included in the FFQ, 132 subjects (61 men and 71 women) aged 20 years or older twice completed a 168-item FFQ (FFQ1, FFQ2), with a 14-month interval between FFQ1 and FFQ2. Over the 1-year interval, 12 dietary recalls (DRs) were collected (1 each month) to assess the validity of the FFQ. Seventeen food groups were derived from the FFQ based on methods described in previous studies. Age-adjusted and deattenuated Spearman correlation coefficients were used to assess the validity of the FFQ.
Results: The mean (SD) age and body mass index of subjects were 35.5 (16.8) years and 25.5 (5.2) kg/m², respectively. Validity correlation coefficients ranged from 0.03 (liquid oil) to 0.77 (simple sugars) in men (median, 0.44), and from 0.12 (snacks) to 0.79 (simple sugars) in women (median, 0.37). The energy-adjusted intraclass correlation coefficient, which reflects the reproducibility of the FFQ, was 0.51 in men and was highest for tea and coffee (0.91); in women it was 0.59 and was highest for simple sugars (0.74). The highest percentage of complete agreement and disagreement was observed for snacks and desserts (60.6%) and potatoes and dairy products (12.8%), respectively, in men, and tea and coffee (62.9%) and legumes (15.7%) in women.
Conclusions: The FFQ that was designed for the TLGS was found to be reliable and valid for assessing the intake of several food groups.

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Background: Mortality/incidence predictions are used for allocating public health resources and should accurately reflect age-related changes through time. We present a new forecasting model for estimating future trends in age-related breast cancer mortality for the United States and England–Wales.
Methods: We used functional data analysis techniques both to model breast cancer mortality-age relationships in the United States from 1950 through 2001 and England–Wales from 1950 through 2003 and to estimate 20-year predictions using a new forecasting method.
Results: In the United States, trends for women aged 45 to 54 years have continued to decline since 1980. In contrast, trends in women aged 60 to 84 years increased in the 1980s and declined in the 1990s. For England–Wales, trends for women aged 45 to 74 years slightly increased before 1980, but declined thereafter. The greatest age-related changes for both regions were during the 1990s. For both the United States and England–Wales, trends are expected to decline and then stabilize, with the greatest decline in women aged 60 to 70 years. Forecasts suggest relatively stable trends for women older than 75 years.
Conclusions: Prediction of age-related changes in mortality/incidence can be used for planning and targeting programs for specific age groups. Currently, these models are being extended to incorporate other variables that may influence age-related changes in mortality/incidence trends. In their current form, these models will be most useful for modeling and projecting future trends of diseases for which there has been very little advancement in treatment and minimal cohort effects (eg. lethal cancers).

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Background: An ideal classification should have maximum intercategory variance and minimal intracategory variance. Health insurance claims typically include multiple diagnoses and are classified into different disease categories by choosing principal diagnoses. The accuracy of classification based on principal diagnoses was evaluated by comparing intercategory and intracategory variance of per-claim costs and the trend in accuracy was reviewed.
Methods: Means and standard deviations of log-transformed per-claim costs were estimated from outpatient claims data from the National Health Insurance Medical Benefit Surveys of 1995 to 2007, a period during which only the ICD10 classification was applied. Intercategory and intracategory variances were calculated for each of 38 mutually exclusive disease categories and the percentage of intercategory variance to overall variance was calculated to assess the trend in accuracy of classification.
Results: A declining trend in the percentage of intercategory variance was observed: from 19.5% in 1995 to 10% in 2007. This suggests that there was a decline in the accuracy of disease classification in discriminating per-claim costs for different disease categories. The declining trend temporarily reversed in 2002, when hospitals and clinics were directed to assign the principal diagnosis. However, this reversal was only temporary and the declining trend appears to be consistent.
Conclusions: Classification of health insurance claims based on principal diagnoses is becoming progressively less accurate in discriminating per-claim costs. Researchers who estimate disease-specific health care costs using health insurance claims must therefore proceed with caution.

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