BACKGROUND: Few studies have examined social inequalities in self-rated health in Japan, and the issue of gender differences related to social inequalities in self-rated health remains inconclusive. METHODS: The data derived from interviews with 2987 randomly selected Japanese adults in four prefectures in Japan who completed the cross-national World Mental Health survey from 2002 through 2005. We calculated odds ratios (ORs) of having poor self-rated physical and mental health by two social class indicators independently with multivariate logistic regression models, adjusted for age, gender, marital status, and area. Stratified analyses by gender and age group were also conducted. RESULTS: The adjusted ORs of the lowest educational attainment category having poor self-rated physical and mental health were 1.42 (95% confidence interval [CI]: 1.15-1.76) and 1.37 (95% CI: 1.10-1.70), respectively. Among females, educational attainment had significant linear associations with selfrated physical and mental health. Adjusted household income was also significantly associated with self-rated physical health among female respondents. No associations were found among males. While educational attainment was associated with self-rated health among the young age group, adjusted household income was associated with self-rated physical health in the middle and old age group. CONCLUSION: These results indicated social inequalities in self-rated health and prominent social inequalities in self-rated health among females in Japan. Social inequalities in self-rated health seemed to exist across age groups. However, the mechanism of social inequalities in self-rated health could be different depending on the age group. J Epidemiol 2006; 16: 223-232.
BACKGROUND: The Ser326Cys polymorphism in human oxoguanine glycosylase 1 (hOGG1), which is involved in the repair of 8-hydroxy-2-deoxyguanine in oxidatively damaged DNA, has been associated with susceptibility to certain cancers, but has not been examined in causation of hepatocellular carcinoma (HCC). METHODS: We conducted a case-control study to investigate whether this polymorphism was related to HCC risk with any interaction with alcohol consumption and cigarette smoking. Genotyping was performed by a polymerase chain reaction with confronting two-pair primers among 209 newly diagnosed HCC cases, 275 hospital controls, and 381 patients with chronic liver disease (CLD) without HCC. RESULTS: Overall, the hOGG1 genotype was not significantly associated with HCC; adjusted odds ratios (and 95% confidence intervals) for the Ser/Cys and Cys/Cys genotypes compared with the Ser/Ser genotype were 0.79 (0.35-1.79) and 0.48 (0.18-1.27) against hospital controls, and 1.51 (0.96-3.37) and 0.86 (0.50-1.47) against CLD patients. We could not detect any significant gene-alcohol interaction (p = 0.95 or 0.16) or gene-smoking interaction (p = 0.70 or 0.69). CONCLUTIONS: These results suggest that the hOGG1 Ser326Cys polymorphism may not play a major role as an independent factor in hepatocarcinogenesis. J Epidemiol 2006; 16 :233-239.
BACKGROUND: During recent decades, colorectal cancer incidence rates have been rapidly increasing in Japan. To investigate trends in colorectal cancer incidence rates, we analyzed incidence data during 39 years between 1959 and 1997 in Miyagi Prefecture, Japan. METHODS: Using age-period-cohort models, we evaluated the effects of time period and cohort on colon and rectal cancer incidence. Model fitting was based on eleven 5-year age groups (30-34 to 80-84), eight 5-year time periods, and 18 overlapping birth cohorts of 10 years each. RESULTS: The analysis found a significant (p=0.04) and upward period effect on female colon cancer incidence, and a significant (p<0.01) and upward cohort effect on male colon cancer incidence. An upward period effect was also observed for male colon cancer incidence without significance. For rectal cancer incidence, a significant cohort effect was found among both males and females. CONCLUSIONS: In light of known risk factors of colorectal cancer, the effects of period and cohort might be related to the change in the prevalence of risk factors such as high intake of meat and animal fat, and obesity. The improved diagnostic procedures including the spread of cancer screening might be responsible for the period effect. Although the significant cohort effects may give a caution for a continuous increase of colorectal cancer incidence, the future trend may be influenced by the period-related factors. Successive monitoring of cancer incidence and prevalence of risk factors is required. J Epidemiol 2006; 16: 240-248.
BACKGROUND: There are few studies about dietary supplement use and nutrient intake from these products in Japan. The purpose of this study was to clarify (1) the prevalence of dietary supplement use, (2) the characteristics of dietary supplement users, (3) nutrient intake from dietary supplements, and (4) the existence of dietary supplement users who took excessive nutrients from these products. METHODS: To collect the information on dietary supplement use in the previous year and nutrient intake from these products, we conducted a self-administered dietary supplement frequency questionnaire. The subjects were 2,259 people aged 40-82 years. Dietary supplements were grouped into 8 major categories. A dietary supplement database was developed to estimate nutrient intake from these products. Excess users were defined as people who consumed more nutrient than the tolerable upper intake level of the Dietary Reference Intakes for Japanese. RESULTS: In the previous year, 55 % of males and 61 % of females consumed dietary supplements. Dietary supplement use was especially prevalent in females, subjects who felt unhealthy, and subjects who were more careful of maintaining an appropriate weight, though the association was affected by the frequency of dietary supplement use. The most common dietary supplements were drink type in males and vitamins in females. Some nutrient values obtained from dietary supplements were higher than those from food. Excess users were found for intake of vitamin A, B6, K, niacin, iron, and magnesium. CONCLUSIONS: It is important to clarify dietary supplement use and to estimate nutrient intake from these products. J Epidemiol 2006; 16: 249-260.
BACKGROUND: The clinico-epidemiologic relevance of the reduction in the frequency of going outdoors in older adults has not been well characterized. This study examined whether the frequency of going outdoors has predictive values for incident physical disability and recovery among community-dwelling elderly. METHODS: One thousand, two hundred and sixty-seven persons aged 65+ years who lived in a rural community in Niigata, Japan, and participated in the baseline survey were assessed again 2 years later in terms of mobility, and instrumental and basic activities of daily living (IADL and BADL). We compared the incident disability and recovery at follow-up among three subgroups classified by the baseline frequency of going outdoors: once a day or more often, once per 2-3 days, and once a week or less often. Multivariate analyses tested associations between the frequency of going outdoors and functional transition, independent of potential confounders. RESULTS: A lower frequency of going outdoors at baseline was associated with a greater incident disability, and a lower recovery at the two-year follow-up. Even after adjustment, the effects of going outdoors remained significant. Adjusted risks of incident mobility and IADL disabilities were significantly higher (odds ratio[OR]=4.02, 95% confidence interval [CI]: 1.77-9.14 and OR=2.65, 95% CI: 1.06-6.58), respectively, and recovery from mobility disability was significantly lower (OR=0.29, 95% CI: 0.08-0.99) for "once a week or less often" subgroup compared with "once a day or more often" subgroup. CONCLUSION: The frequency of going outdoors is a good predictor for incident physical disability and recovery among community-living elderly. Public health nurses and clinicians should pay more attention how often their senior clients usually go outdoors. J Epidemiol 2006; 16: 261-270.