Background: Helicobacter pylori (H. pylori) is an established causative factor of gastric cancer. Although the expansion of insurance coverage has led to an increase in the number of patients treated for H. pylori, the population impact of eradication treatment for H. pylori has been scarcely investigated. This study aimed to clarify the long-term responses of H. pylori antibody titer after eradication treatment using large scale cross-sectional data from the Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT Study).

Methods: A total of 55,282 Japanese participants aged 40 to 74 years residing in 16 areas provided blood samples from 2011 through 2016. From these, treated (n = 6,276) and untreated subjects who were seropositive for H. pylori or had serological atrophy (n = 22,420) formed the study population (n = 28,696). Seropositivity was defined as an anti-H. pylori IgG titer of ≥10 U/mL. Antibody level was compared among subjects according to self-reported treatment history as untreated, and treated for less than 1 year (<1Y), 1 through 5 years (1–5Y), and 6 or more years ago (6Y+).

Results: Median serum antibody titer was 34.0 U/mL, 7.9 U/mL, 4.0 U/mL, and 2.9 U/mL for the untreated, <1Y, 1–5Y, and 6Y+ groups, respectively. While those treated for H. pylori within the previous year had a 76.8% lower antibody titer compared to untreated subjects, approximately 41% of subjects were still seropositive.

Conclusion: A significant reduction in H. pylori antibody titer occurs within 1 year after eradication treatment, but that a long period is needed to achieve complete negative conversion.

Background: While a wide range of predictors of postpartum smoking relapse have been suggested, population-based studies have rarely examined these factors exclusively among women who quit in early pregnancy. Furthermore, workplace secondhand smoke (SHS) exposure has never been examined.

Methods: We analyzed data from 10,466 pregnant women who participated in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study. Age, education, parity, breastfeeding, postpartum depression, SHS exposure at home, and SHS exposure at work (not working, working without SHS exposure, working with SHS exposure) were evaluated as possible predictors. Multiple logistic regression analyses were conducted to examine the associations between these factors and smoking relapse by 1 year postpartum among women who quit in early pregnancy. Analyses stratified by SHS exposure at home were also conducted.

Results: About one-fourth of early-pregnancy quitters had relapsed into smoking by 1 year postpartum. Lower education, multiparity, not breastfeeding, postpartum depression, and SHS exposure at home were associated with increased risks of smoking relapse. Working with SHS exposure was associated with an increased risk of smoking relapse; the multivariate-adjusted odds ratios of working without SHS exposure and working with SHS exposure compared with not working were 1.14 (95% confidence interval [CI], 0.82–1.59) and 2.18 (95% CI, 1.37–3.46), respectively. The significant association of workplace SHS exposure was observed only among women without SHS exposure at home.

Conclusion: SHS exposure at work, as well as education, multiparity, breastfeeding, postpartum depression, and SHS exposure at home were associated with postpartum smoking relapse among early-pregnancy quitters.

Background: Encouraging older adults to continue working longer would be a realistic solution to the shrinking labor force, which is a result of the aging population. This study examined whether working longer improves the health of older adults.

Methods: We used repeated cross-sectional data from 1,483,591 individuals aged 55–69 years collected from 11 waves of a nationwide population-based survey conducted in Japan from 1986 to 2016. We estimated pooled regression models to explain health outcomes by work status, controlling for potential endogeneity biases. Based on the estimation results, we conducted simulations to predict the health impact of policy measures that encourage older adults to participate in the labor force.

Results: The regression analysis showed that work status had a mixed health impact. For example, work reduced the probability of poor self-rated health by 6.7 (95% confidence interval [CI], 6.2–7.2) percentage points and increased that of psychological distress by 12.2 (95% CI, 11.3–13.1) percentage points. The simulation results showed that raising both the mandatory retirement age and eligibility age for claiming public pension benefits to 70 years would increase the employment rate by 27.8 (standard deviation [SD], 4.2) percentage points among those aged 65–69 years, which would reduce their probability of poor self-rated health by 1.8 (SD, 0.4) percentage points and raise that of psychological distress by 4.1 (SD, 0.8) percentage points for that age group.

Conclusion: The results suggest the need to pay attention to the health outcomes of policy measures that encourage older adults to work longer.

Background: No studies have examined the associations between adult height and ischemic stroke subtypes.

Methods: We conducted a population-based case-control study that included 2,451 thrombotic and 687 embolic stroke cases, as well as 1,623 intracerebral and 768 subarachnoid hemorrhage cases without history of stroke aged 40–79 years, and the same number of sex- and age-matched controls. Cases and controls were grouped according to the quintile cut-off values of height in controls, and the third quintile, which was approximately the average height group, was used as the reference group. Height divided by one standard deviation of height in controls was also examined as a continuous variable. The analyses were carried out separately for participants aged 40–59 years and 60–79 years.

Results: In both younger and older men, height was linearly inversely associated with total and thrombotic strokes, and the shortest quintile compared to the reference group was associated with increased risks of these strokes. Although height was linearly inversely associated with embolic stroke and intracerebral hemorrhage in younger men, the shortest quintile did not show increased risks of these strokes. Height did not seem to be associated with total stroke and any stroke subtypes in younger women. In contrast, the tallest quintile was significantly associated with increased risks of total stroke and intracerebral hemorrhage, and height tended to be positively associated with these strokes in older women.

Conclusion: We reported the associations between adult height and ischemic stroke subtypes for the first time, which differed according to sex and age group.

Background: Both decreased insulin sensitivity and impaired insulin secretion are common in Asian populations with diabetes, in contrast to Western populations. There is limited evidence regarding the association between insulin response in diabetes in Asian populations and serum 25-hydroxyvitamin D₃ (25[OH]D₃) insufficiency.

Methods: The present cross-sectional study compared the prevalence of diabetes, defined as a fasting plasma glucose level ≥126 mg/dL and/or a HbA1c level ≥6.5%, among 480 participants aged 35–79 years not taking anti-diabetes medications, based on serum 25(OH)D₃ levels. A logistic regression model was used to calculate the odds ratios for diabetes in each serum 25(OH)D₃ group. Furthermore, this study examined the association between serum 25(OH)D₃ levels and the index of homeostasis model assessment of insulin resistance (HOMA-IR) using a linear regression model.

Results: The prevalence of diabetes was 7.29% in the study population, and was higher in lower serum 25(OH)D₃ quartile groups. The odds ratios for diabetes in the first, second, and third serum 25(OH)D₃ quartile groups (25[OH]D₃: ≤18.10, 18.11–22.90, and 22.91–28.17 ng/mL) were 4.02 (95% confidence interval [CI], 1.25–12.92), 2.50 (95% CI, 0.77–8.10), and 1.91 (95% CI, 0.60–6.09), respectively, with the fourth quartile group (⩾28.18 ng/mL) serving as the reference group, after adjusting for sociodemographic, lifestyle, physical and environmental factors. Serum 25(OH)D₃ levels showed an inverse association with log-transformed HOMA-IR after adjusting for similar factors (standardized β = −0.08; 95% CI, −0.14 to −0.02).

Conclusion: Serum 25(OH)D₃ levels were inversely associated with diabetes prevalence in a general Japanese population, with a slight inverse association between serum 25(OH)D₃ levels and HOMA-IR.

Background: Prioritization for novel coronavirus disease 2019 (COVID-19)-related health policies usually considers age and certain other characteristics, but sex is rarely included, despite the higher risk of severe disease in men. The aim of this study was to compare the impact of sex and age on the severity of COVID-19 by estimating the age difference in years for which the risk for men versus women is the same.

Methods: We analyzed 23,414 Japanese COVID-19 inpatients aged 20–89 years (13,360 men and 10,054 women). We graded the severity of COVID-19 (0 to 5) according to the most intensive treatment required during hospitalization. The risk of grade 2/3/4/5 (non-invasive positive pressure ventilation/invasive mechanical ventilation/extracorporeal membrane oxygenation/death), grade 3/4/5, and separately grade 5 was analyzed using a multiple logistic regression model.

Results: The odds ratio (OR) of grades 2/3/4/5, 3/4/5 (primary outcome), and 5 for men relative to women was 2.76 (95% CI, 2.44–3.12), 2.78 (95% CI, 2.42–3.19), and 2.60 (95% CI, 2.23–3.03), respectively, after adjustment for age and date of admission. These risks for men were equivalent to those for women 14.1 (95% CI, 12.3–15.8), 11.2 (95% CI, 9.7–12.8), and 7.5 (95% CI, 6.3–8.7) years older, respectively.

Conclusion: The risks of worse COVID-19 prognosis (grades 3/4/5) in men were equivalent to those of women 11.2 years older. Reanalyzing data extracted from four previous studies also revealed a large impact of sex difference on the severity of COVID-19. We should pay more attention to sex differences to predict the risk of COVID-19 severity and to formulate public health policy accordingly.

Background: Japan has witnessed an unusual increase in the number of suicides among women during the coronavirus disease 2019 pandemic. An analysis is required to identify the influencing factors during the pandemic and develop new measures for preventing suicides.

Methods: Data on the number of monthly suicides were collected from the National Police Agency of Japan. The expected number of suicides among women during the pandemic was estimated using a time-series model based on pre-pandemic data, considering year-to-year trends. The observed-to-expected (O/E) ratio of suicides was estimated from March 2020 to October 2021 using job status, suicide motive, and age.

Results: The number of suicides among women in Japan increased beyond the expected number until October 2021. The O/E ratio based on job status, suicide motive, and age (except self-employed, unknown job status, and women aged ≥80 years) was significantly above 1.0 from March–December 2020, and the increase in suicides continued in almost all categories in 2021.

Conclusion: Although several reasons were reported for increased suicides among women in Japan during the pandemic (eg, economic downturn, financial instability, and loneliness), suicides increased irrespective of job status, suicide motive, or age. Comprehensive measures to prevent suicide might have been important during the pandemic, instead of limiting interventions to the reported specific population.

Background: This cohort was established to evaluate whether 38-year radiation exposure (since the start of nuclear reactor operations) is related to cancer risk in residents near three nuclear power plants (NPPs).

Methods: This cohort study enrolled all residents who lived within 8 km of any of the three NPPs in Taiwan from 1978 to 2016 (n = 214,502; person-years = 4,660,189). The control population (n = 257,475; person-years = 6,282,390) from three towns comprised all residents having lived more than 15 km from all three NPPs. Radiation exposure will be assessed via computer programs GASPAR-II and LADTAP-II by following methodologies provided in the United States Nuclear Regulatory Commission regulatory guides. We calculated the cumulative individual tissue organ equivalent dose and cumulative effective dose for each resident. This study presents the number of new cancer cases and prevalence in the residence-nearest NPP group and control group in the 38-year research observation period.

Conclusion: TNPECS provides a valuable platform for research and opens unique possibilities for testing whether radiation exposure since the start of operations of nuclear reactors will affect health across the life course. The release of radioactive nuclear species caused by the operation of NPPs caused residents to have an effective dose between 10⁻⁷ and 10⁻³ mSv/year. The mean cumulative medical radiation exposure dose between the residence-nearest NPP group and the control group was not different (7.69; standard deviation, 18.39 mSv and 7.61; standard deviation, 19.17 mSv; P = 0.114).