Late Dr Takeshi Hirayama and his colleagues conducted a mortality follow-up of a large-scale cohort in six prefectures in Japan. This study is called the six-prefecture cohort study or Hirayama Cohort Study. The study subjects were residents aged 40 years or older at the baseline survey in 1965, which covered 94.8% of residents identified in the study area by the National Census conducted on October 1, 1965. The mortality of 264,118 cohort members was followed until the end of 1982. One of the most important findings made by this study was an association between second-hand smoke exposure and lung cancer. This finding is the origin of the worldwide spread of smoking ban in indoor public venues and workplaces. Other major findings obtained from the study are also briefly described in this article.
Background: Guidelines recommend against all codeine use in children for its common indications of analgesia and cough suppression because of uncertain benefits and potential risk of death. However, because of its rarity, the occurrence of severe respiratory depression associated with codeine-containing antitussives has been poorly investigated. The objective of this study was to investigate the association between codeine-containing antitussives and severe respiratory depression in children.
Methods: We retrospectively identified Japanese children who were prescribed antitussives for respiratory diseases from a large Japanese administrative claims database (JMDC, Tokyo, Japan). We collected data on baseline characteristics including age, sex, and comorbidity. Each case was matched with four controls with the same sex and age in the same year from the same type of medical institution. We then examined the association between codeine-containing antitussives and subsequent severe respiratory depression using multivariable conditional logistic regression analysis.
Results: Of 164,047 children, 18,210 (11.1%) were prescribed codeine-containing antitussives. Of the children who took codeine-containing drugs, seven experienced severe respiratory depression. After adjusting for confounding factors, there was no significant difference in the proportion of severe respiratory depression between children with and without codeine-containing antitussives (odds ratio 1.15; 95% confidence interval, 0.48–2.78).
Conclusion: Occurrence of respiratory depression was very rare, and the association of codeine with respiratory depression was insignificant, even in a large sample of children in Japan.
Background: Cognitive dysfunction has been recognized as a diabetes-related complication. Whether hyperglycemia or elevated fasting glucose are associated with cognitive decline remains controversial. We aimed to investigate the relationship between fasting glucose levels and cognitive function in diabetic and non-diabetic individuals.
Methods: Participants were Japanese diabetic (n = 191) and non-diabetic (n = 616) men, aged 46–81 years, from 2010–2014. Blood samples were taken after a 12 h fast. The Cognitive Ability Screening Instrument (CASI), with a maximum score of 100, was used for cognitive assessment. Cognitive domains of CASI were also investigated. Fractional logit regression with covariate adjustment for potential confounders was used to model cross-sectional relationships between fasting blood glucose and CASI score.
Results: For diabetic individuals, CASI score was 0.38 (95% confidence interval: 0.66–0.12) lower per 1 mmol/L higher fasting glucose level. Short-term memory domain also exhibited an inverse association. For non-diabetic individuals, a reverse U-shaped relationship was observed between fasting glucose and cognitive function, identifying a threshold for highest cognitive performance of 91.8 CASI score at 3.97–6.20 mmol/L (71.5–111.6 mg/dL) fasting glucose. Language ability domain displayed a similar relationship with fasting glucose.
Conclusions: Elevated fasting glucose levels in diabetic men were associated with lower cognitive function, in which short-term memory was the main associated domain. Interestingly, in non-diabetic men, we identified a threshold for the inverse relationship of elevated fasting glucose with cognitive function. Contrastingly to diabetic men, language ability was the main associated cognitive domain among non-diabetic men.
Background: The prevalence of overweight is increasing dramatically worldwide. The aim of our study was to investigate the association of plain water intake (PWI) with the risk of new-onset overweight risk among Chinese adults.
Methods: A total of 3,200 adults aged 18–65 who were free of overweight at baseline were enrolled from China Health and Nutrition Survey (CHNS) cohort study in 2006–2011. The risk of new-onset overweight with different amounts of PWI per day was analyzed in this 5-year cohort. A multiple logistic regression model was used to assess the association of PWI and the risk of new-onset overweight and adjust for potential confounders. Moreover, dose-response models were developed to estimate the linear relationship.
Results: During 5 years of follow-up, 1,018 incident cases were identified. Our analysis indicated an inverse association of more than 4 cups of PWI per day and the risk of new-onset overweight among normal weight individuals. Compared with participants who drank 2 to 3 cups PWI, the adjusted odds ratios (OR) of overweight were 0.741 (95% confidence interval [CI], 0.599–0.916) in participants who drank 4 to 5 cups PWI, and 0.547 (95% CI, 0.435–0.687) in participants who drank more than 6 cups PWI. The dose-response analysis showed that every cup of PWI was associated with a 6.5% and 8.4% decrease in the risk of new-onset overweight among men and women, respectively. The interactions of PWI and covariates on the risk of overweight were not found.
Conclusion: Drinking more than 4 cups (≈1 liter) per day of plain water is associated with decrease in the risk of new-onset overweight among normal-weight individuals.
Background: Higher smoking prevalence in less educated persons and manual workers is well known. This study examines the independent relationship of education and occupation with tobacco use.
Methods: We used anonymized data from a nationwide population survey (30,617 men and 33,934 women). Education was divided into junior high school, high school, or university attainment. Occupation was grouped into upper non-manual, lower non-manual, and manual. Poisson regression models stratified by age and gender were used to estimate adjusted prevalence ratio (PR) and 95% confidence interval (CI) for current smoking.
Results: After adjustment for covariates, education, and occupation, education was significantly related to current smoking in both genders; compared to university graduates, PRs of junior high school graduates aged 20–39, 40–64, and ≥65 were 1.74 (95% CI, 1.53–1.98), 1.50 (95% CI, 1.36–1.65), and 1.28 (95% CI, 1.08–1.50) among men, and 3.54 (95% CI, 2.92–4.30), 2.72 (95% CI, 2.29–3.23), and 1.74 (95% CI, 1.14–2.66) among women, respectively. However, significantly higher smoking prevalence in manual than in upper non-manual was found only in men aged 20–64; compared to upper non-manual, the PRs of manual workers aged 20–39, 40–64, and ≥65 were 1.11 (95% CI, 1.02–1.22), 1.18 (95% CI, 1.10–1.27), and 1.10 (95% CI, 0.89–1.37) among men, and 0.95 (95% CI, 0.75–1.20), 0.92 (95% CI, 0.75–1.12), and 0.46 (95% CI, 0.22–0.95) among women, respectively.
Conclusions: Independent of occupation, educational disparities in smoking existed, regardless of age and gender. Occupation-smoking relationship varied with age and gender. Our study suggests that we should pay attention to social inequality in smoking as well as national smoking prevalence.
Background: Accumulating evidence has shown that high-quality early childhood education and care may be an effective way of promoting children’s optimal health and development, especially for the most disadvantaged. However, socially disadvantaged families are less likely to enroll children in center-based childcare. In this study, we explored characteristics associated with use of center-based childcare among Japanese families.
Methods: We used data from two Japanese birth cohorts in 2001 (n = 17,019) and 2010 (n = 24,333). Enrollment in center-based childcare was assessed at the ages of three and four years in the 2001 cohort and at the age of three in the 2010 cohort. Logistic regression analyses were conducted.
Results: Children in the lowest quintile of household income were 1.54 (95% confidence interval, 1.20–1.98) times more likely to not receive center-based childcare than those in the highest-income quartile at the age of four in the 2001 cohort. Other socio-economic disadvantage (mother’s low education, non-Japanese parent, and higher number of siblings) and child’s health and developmental problems (preterm birth, congenital diseases, and developmental delay) were also associated with the non-use of center-based childcare at the age of three in the 2001 and 2010 cohorts.
Conclusions: An inverse care law operates in the use of early childhood education (ie, children with the least need enjoy the highest access). Children with socio-economic, health, and developmental disadvantages are at a greater risk of not receiving early childhood education and care. Social policies to promote equal access to early childhood education are needed to reduce future socio-economic inequalities.