Although the causal relationships of high serum levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) with coronary artery disease (CAD) are well established, there have been few community-based epidemiologic studies of these relations in Japan. Furthermore, even when analysis is restricted to ischemic stroke, the relationship between dyslipidemia and stroke is very weak. Accordingly, it is difficult to perform cohort studies of dyslipidemia and cardiovascular disease. A series of studies, such as the NIPPON DATA (National Integrated Project for Prospective Observation of Non-communicable Disease and Its Trends in the Aged) cohort study of a representative sample of Japanese, have greatly increased existing evidence. NIPPON DATA80 revealed a clear positive relationship between TC and CAD, and indicated that reverse causality between hypocholesterolemia and liver disease may increase all-cause mortality in hypocholesterolemic Japanese. NIPPON DATA90 showed that serum high-density lipoprotein cholesterol (HDL-C) was inversely associated with all-cause mortality, even when HDL-C was very high. NIPPON DATA80 revealed that low-normal levels of serum albumin and TC are associated with a decline in activity during old age, especially in women. The Suita study—a unique cohort study of urban residents—showed that LDL-C and non–HDL-C were equally accurate in predicting the incidence of myocardial infarction. Further research of this quality is needed to ascertain the public health burden of dyslipidemia in Japan.
Homocysteine is a risk factor for atherosclerosis, and the level of homocysteine in plasma is known to be strongly influenced by genetic factors—not only rare variants, but also common polymorphisms. This report describes a comprehensive postgenomic strategy for elucidating useful genetic information about homocysteine metabolism. The standard method for gathering such information is the candidate gene approach, which is an effective method based on known biological information. After collecting evidence from independent research projects, a critical epidemiological review permits a determination as to whether a putative association is true or not. A genome-wide association study (GWAS), which requires no biological information, can identify new candidates and confirm associations suggested by the candidate gene approach. The importance of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism, which was shown in a randomized controlled trial conducted by the present author, and in other studies, was independently confirmed by a large-scale GWAS. GWASs have also identified new candidate genes, but these must be confirmed by independent studies. In homocysteine metabolism, the classical candidate gene approach was sufficiently robust to detect the true association. However, candidate markers newly discovered by GWAS need to be confirmed by well-designed epidemiological studies to determine their significance. International statements, such as CONSORT and STREGA, provide useful principles for conducting such research.
Background: The prevalence of tinnitus is reported to be high in older Western populations, and several risk factors have been suggested. However, community-based evidence on prevalence is limited and, to our knowledge, there is no such information from older non-Western populations. The purpose of this study was to determine the prevalence and factors associated with tinnitus in community-dwelling Japanese elders. Methods: In this community-based cross-sectional study, 1320 residents of Kurabuchi Town aged 65 years or older (584 men and 736 women; participation proportion = 98.7%) were interviewed at home in 2006, and information on tinnitus and factors associated with tinnitus was collected. We estimated the prevalence of tinnitus by age group and sex and used a logistic regression model to investigate associated factors. Results: The prevalence of tinnitus was 18.6% (men: 18.0%; women: 19.0%); there were no statistically significant differences by age group or sex. Hearing difficulty, depressive mood, prescribed medication, past/current history of coronary heart disease, and knee joint pain requiring medical consultation were associated with tinnitus. Conclusions: These findings suggest that tinnitus is common in Japanese aged over 65 years. Because the factors associated with tinnitus in this cross-sectional study are potentially modifiable, they should be thoroughly investigated in a longitudinal study.
Background: Recent research highlights the importance of environment as a determinant of physical activity; however, evidence among Japanese is sparse. The aim of this study was to examine the association between perceived neighborhood environment and neighborhood walking for multiple purposes among Japanese. Methods: We conducted a population-based, cross-sectional study of 1461 Japanese adults (age: 48.2 ± 14.1 years, men: 44.8%). Neighborhood environment and walking were assessed by a validated questionnaire. The odds ratio of active walkers was calculated in relation to environmental characteristics after adjustment for age, sex, and other potential confounders. Results: Participants were more likely to walk when they perceived that there was high residential density (odds ratio, 1.47; 95% confidence interval, 1.11–1.96), fair land use mix–diversity (1.37, 1.04–1.81), good walking/cycling facilities (1.56, 1.19–2.04), and attractive aesthetics (1.49, 1.14–1.95). Environmental factors associated with walking differed with respect to the purpose for walking. The environmental characteristics associated with walking for daily errands and with walking for commuting were similar, and included residential density and land use mix. Walking for leisure was associated with walking/cycling facilities, aesthetics, and traffic safety. Stratified analyses showed some sex-specific associations. Among women, there was an unexpected inverse association of leisure walking with both residential density and land use mix–diversity. Conclusions: The association between neighborhood environment and walking differed by walking purpose. The results were generally consistent with those of studies conducted in Western countries, except for the association of high residential density and good land use mix–diversity with less leisure walking in women. These results suggest possible targets for environmental interventions to promote walking.
Background: The use of high-density barium sulfate was recommended by the Japan Society of Gastroenterological Cancer Screening (JSGCS) in 2004. We evaluated the diagnostic validity of gastric cancer screening that used high-density barium sulfate. Methods: The study subjects were 171 833 residents of Osaka, Japan who underwent gastric cancer screening tests at the Osaka Cancer Prevention and Detection Center during the period from 1 January 2000 through 31 December 2001. Screening was conducted using either high-density barium sulfate (n = 48 336) or moderate-density barium sulfate (n = 123 497). The subjects were followed up and their medical records were linked to those of the Osaka Cancer Registry through 31 December 2002. The results of follow-up during 1 year were defined as the gold standard, and test performance values were calculated. Results: The sensitivity and specificity of the screening test using moderate-density barium sulfate were 92.3% and 91.0%, respectively, while the sensitivity and specificity of the high-density barium test were 91.8% and 91.4%, respectively. The results of area under receiver-operating-characteristic (ROC) curve analysis revealed no significant difference between the 2 screening tests. Conclusions: Screening tests using high- and moderate-density barium sulfate had similar validity, as determined by sensitivity, specificity, and ROC curve analysis.
Background: We conducted a case-control study to examine the relationship between human leukocyte antigen-A (HLA-A) allele polymorphism and the pathogenesis of cervical neoplasia among Japanese women. Methods: A total of 119 patients with invasive cervical squamous cell carcinoma were compared to 119 age- and menopausal status-matched non-cancer controls. Blood samples were taken from all cases and controls and lifestyle information was collected by means of a self-administered questionnaire. The estimated impact of HLA-A alleles on cervical cancer risk was evaluated by unconditional logistic regression models. Results: The frequency of HLA-A*0206 among cases was significantly lower than among controls (P = 0.006). There was an inverse association between A*0206 and cervical cancer risk (odds ratio [OR] = 0.31, 95% confidence interval [95% CI] = 0.15 to 0.65, P = 0.002), and a positive association for HLA-A*2402 (OR = 1.76, 95% CI = 1.00 to 3.09, P = 0.048). After correction for multiple comparisons, A*0206 was significantly associated with reduced cervical cancer risk (corrected P = 0.036). Furthermore, the inverse association between A*0206 and cervical cancer risk was independent of smoking status (never smoker: OR = 0.37, 95% CI = 0.15 to 0.90; ever smoker: OR = 0.23, 95% CI = 0.06 to 0.89). Conclusions: There was an inverse association between HLA-A*0206 and cervical cancer risk among Japanese women, which suggests that HLA-A polymorphism influences cervical cancer risk. Further investigation in other populations is thus warranted.
Background: The most recent epidemiologic features of Kawasaki disease (KD) are unknown. Methods: The 20th nationwide survey of KD was conducted in 2009, and included patients treated for the disease in 2007 and 2008. Hospitals specializing in pediatrics, and hospitals with pediatric departments and 100 or more beds, were asked to report all patients with KD during the 2 survey years. Results: From a total of 1540 departments and hospitals, 23 337 patients (11 581 in 2007 and 11 756 in 2008) were reported: 13 523 boys and 9814 girls. The annual incidence rates were 215.3 and 218.6 per 100 000 children aged 0–4 years in 2007 and 2008, respectively. These were the highest annual KD incidence rates ever recorded in Japan. The monthly number of patients peaked during the winter months; smaller increases were noted in the summer months. The age-specific incidence rate showed a monomodal distribution with a peak at age 9–11 months. The prevalences of both cardiac lesions during the acute phase of the disease and cardiac sequelae were higher among infants and older age groups. Conclusions: The incidence rate and number of patients with KD in Japan continue to increase.
Background: In Japan, life expectancy at birth is currently the highest in the world. However, recent trends in disability-free life expectancy in Japan have not been examined. Methods: We used data from Japanese national surveys for the period 1995–2004. These surveys included information on activity status measured by common self-reported instruments. The numbers of expected years with and without activity limitation were estimated by using the Sullivan method. Results: The numbers of expected years of life without activity limitation, at birth, in 1995 and 2004 were 68.5 and 69.7, respectively, in males and 72.1 and 73.0 in females. As a proportion of total life expectancy, at birth, these values represent a decrease from 89.7% to 88.6% in males and from 87.1% to 85.3% in females. The proportion of expected years with a limitation of some activities except activities of daily living (ADL) increased in males and females. The proportion of those with an ADL limitation increased in females, but not in males. Conclusions: The trends in expected years with and without activity limitation suggest that the duration of life with a light or moderate disability increased in Japanese males and females during the period 1995–2004.
Background: Individuals with a self-reported history of sexually transmitted infection (STI) are at high risk for depression. However, little is known about how social support affects the association between STI and depression among young women in Canada. Methods: Data were drawn from the Canadian Community Health Survey (CCHS), conducted in 2005. A total of 2636 women aged 15–24 years who provided information on STI history were included in the analysis. Depression was measured by a depression scale based on the Composite International Diagnostic Interview Short-Form (CIDI-SF). The 19-item Medical Outcomes Study (MOS) Social Support Survey assessed functional social support. A log-binomial model was used to estimate the prevalence ratio (PR) for self-reported STI history associated with depression and to assess the impact of social support on the association. Results: The adjusted PR for self-reported STI history associated with depression was 1.61 (95% CI, 1.03 to 2.37), before social support was included in the model. The association between STI history and depression was no longer significant when social support was included in the model (adjusted PR, 1.28; 95% CI, 0.83 to 1.84). The adjusted PRs for depression among those with low and intermediate levels of social support versus those with a high level of social support were 5.62 (95% CI, 3.50 to 9.56) and 2.19 (1.38 to 3.68), respectively. Conclusions: Social support is an important determinant of depression and reduces the impact of self-reported STI on depression among young women in Canada.
Background: Health literacy affects the acquisition of health knowledge and is thus linked to health outcomes. However, few scales have been developed to assess the level of health knowledge among the general public. Methods: The 15-item Japanese Health Knowledge Test (J-HKT) was developed by using item response theory to score an item pool. We examined the construct validity of the J-HKT in relation to health literacy items, and analyzed the sociodemographic and behavioral factors associated with poor health knowledge. Results: We enrolled 1040 adult participants (mean age, 57 years; women, 52%). The 15 items that best identified people with poor health knowledge were selected. For all items on the J-HKT, the information function curves had a peak in the negative spectrum of the latent trait. As compared with participants reporting high levels of income, educational attainment, and literacy, those with low levels of income, education, and literacy had a lower total score on the J-HKT. As compared with non/light drinkers, moderate and heavy drinkers had lower total scores on the J-HKT. Conclusions: The J-HKT may prove useful in measuring health knowledge among the general public, and in identifying and characterizing those with poor health knowledge.
Background: Polymorphisms in methylenetetrahydrofolate reductase (MTHFR), such as MTHFR C677T and A1298C, are associated with several cancers. This study aimed to evaluate the effects of MTHFR polymorphisms on colon cancer risk and possible interactions with environmental factors in a population from northeastern Thailand. Methods: This hospital-based case–control study was conducted during 2002–2006; 130 colon cancer cases and 130 age- and sex-matched controls were enrolled. Information was collected and blood samples were obtained for assay of MTHFR C677T and A1298C polymorphisms by polymerase chain reaction with restriction fragment length polymorphism techniques. Associations between variables of interest and colon cancer were assessed using conditional logistic regression. Results: Increased risk of colon cancer was associated with alcohol consumption and bowel habits. Alcohol drinkers who consumed ≤0.50 or >0.50 units of alcohol per day had elevated risks (ORadj = 3.5; 95% CI: 1.19–10.25 and ORadj = 1.71; 95% CI: 0.74–3.96, respectively). The risk was also higher in subjects with frequent constipation (11.69; 2.18–62.79) and occasional constipation (3.43; 1.72–6.82). An interaction was observed between the MTHFR C677T polymorphism and freshwater fish consumption on colon cancer risk (P value for interaction = 0.031). Interactions were observed between the MTHFR A1298C polymorphism and bowel habits, family history of cancer, alcohol consumption, and beef consumption on colon cancer risk (P-value for interaction = 0.0005, 0.007, 0.067, 0.003, respectively). Conclusions: In a Thai population, colon cancer risk was associated with alcohol and beef consumption, bowel habits, and family history of cancer. Interactions between MTHFR polymorphisms and environmental factors were also observed.
Background: The aim of the present study was to determine the prevalence of and factors associated with smoking among Japanese medical students, to help promote effective antismoking measures in this population. Methods: From the 80 university medical schools in Japan, 20 were randomly selected and invited to participate in our survey. The survey focused on medical students and employed an anonymous self-administered questionnaire. Information on each university’s antismoking measures was obtained using a separate questionnaire administered to teaching staff. The survey was conducted from December 2006 through March 2007. Factors associated with smoking were identified by using the chi-square test and multiple logistic regression analysis. Results: A total of 1619 valid surveys were returned. The overall prevalence of smoking was 13.7% (18.1% among men and 5.1% among women). Factors associated with smoking among medical students were male sex, enrollment at a private medical university, smoking by siblings, alcohol consumption, coffee consumption, insomnia, and less than 6 hours of sleep per night. Conclusions: Antismoking education must be further promoted to Japanese medical students, with consideration given to the factors associated with smoking behavior found in the present study.