Background: Both short and long interpregnancy intervals (IPIs) have been associated with risk of preterm birth, but the evidence is limited in Asians. It is also uncertain whether the association is modified by dietary folate intake or folic acid supplementation during pregnancy. Thus, we examined associations between IPI and risk of preterm birth and effect modification of those associations by dietary intake of folate and supplementation with folic acid on the basis of a nationwide birth cohort study.

Methods: Among 103,062 pregnancies registered in the Japan Environment and Children’s Study, 55,203 singleton live-birth pregnancies were included in the analysis. We calculated IPI using birth date, gestational age at birth of offspring, and birth data of the latest offspring. Odds ratios (ORs) and 95% confidence intervals (CIs) of the risk of preterm birth were estimated according to IPI categories.

Results: Both <6-month and ≥120-month IPIs were associated with an increased risk of preterm birth, compared with an 18–23-month IPI. The multivariable ORs were 1.63 (95% CI, 1.30–2.04) for <6-month and 1.41 (95% CI, 1.11–1.79) for ≥120-month IPIs. These associations were confined to women with inadequate intake of dietary folate and folic acid supplementation during pregnancy. Multivariable ORs were 1.76 (95% CI, 1.35–2.29) for <6-month IPI and 1.65 (95% CI, 1.24–2.19) for ≥120-month IPI.

Conclusion: Both <6-month and ≥120-month IPIs were associated with an increased risk of preterm birth. These higher risks were confined to women with inadequate intake of dietary folate and folic acid supplementation during pregnancy.

Background: The place of death and related factor, such as diseases, symptoms, family burden, and cost, has been examined, but social background and lifestyle were not considered in most studies. Here, we assessed factors that are associated with the place of death using the largest cohort study in Japan.

Methods: A total of 17,781 deaths from the cohort study were assessed. The study database was created from the Japan Public Health Center-based Prospective Study (JPHC Study), in which demographic data were collected from Japanese Vital Statistics. Adjusted odds ratios for home death were calculated using logistic regression.

Results: Multivariate analysis adjusted for various factors showed that unmarried status (odds ratio [OR] 2.4; 95% confidence interval [CI], 2.0–2.9), unemployed male (OR 1.3; 95% CI, 1.1–1.5), and high drinking level in male (OR 1.3; 95% CI, 1.1–1.6) were associated with home death. Regarding the cause of death, cardiovascular disease (OR 3.3; 95% CI, 2.9–3.8), cerebrovascular disease (OR 1.9; 95% CI, 1.6–2.2), and external factors (OR 4.1; 95% CI, 3.5–4.8) were significantly associated with home death, compared with cancer. The risk of death at home was significantly higher among unmarried subjects stratified by cause of death (cardiovascular disease: OR 3.2; 95% CI, 2.2–4.7; cerebrovascular disease: OR :5.1; 95% CI, 2.9–9.1; respiratory disease: OR 3.4; 95% CI, 1.6–7.6; and external factors: OR 2.3; 95% CI, 1.4–3.7), but for cancer, the risk of death at home tended to be higher among married participants.

Conclusion: This study found that various factors are associated with home death using the largest cohort study in Japan. There is a high possibility of home deaths in people with fewer social connections and in those with diseases leading to sudden death.

Background: The present study analyzed the relation of disaster exposure prior to pregnancy with maternal characteristics and obstetric outcomes.

Methods: The participants were 13,148 pregnant women recruited from 2013 to 2017. The women were classified into three groups by the severity of housing damage caused by the Great East Japan Earthquake of 2011: group A, house was not destroyed/did not live in the disaster area; group B, half/part of the house was destroyed; and group C, house was totally/mostly destroyed. Maternal characteristics, hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM), and gestational weeks were obtained using questionnaires and medical records. Multiple logistic regression analyses were performed to investigate the relation between disaster exposure and maternal characteristics, HDP, and GDM. A structural equation model was applied to investigate the relation of disaster exposure with HDP and gestational weeks.

Results: The homes of about 11% of the women were totally/mostly destroyed. For groups B and C compared with those in group A, the adjusted ORs for HDP were 1.04 and 1.26 (P for trend = 0.01), and for GDM were 0.89 and 1.14 (P for trend = 0.9), respectively. Pre-pregnancy body mass index (BMI) mediated 23.2% of the relation between disaster exposure and HDP. Disaster exposure was associated with gestational weeks.

Conclusion: Disaster exposure at least 2.5 years before pregnancy was found to be associated with maternal characteristics and the prevalence of HDP. Pre-pregnancy BMI mediated the relation between disaster exposure and the prevalence of HDP, and gestational weeks were reduced through HDP.

Background: Basic and instrumental activities of daily living (BADL and IADL, respectively) are known predictors of mortality. However, the relationship between higher-level functional capacity (HLFC) and mortality and related sex differences have rarely been investigated.

Methods: A prospective population-based cohort study was conducted in 1,824 older residents (≥65 years) with independent BADL from 300 randomly selected areas in Japan from 1995, and the participants were followed up until 2010. Using the Cox proportional hazards model, the relationship between HLFC and mortality risk was investigated, with adjustment for possible confounders. HLFC was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence. Baseline data were collected using a questionnaire or by home-visit interviews.

Results: During an average 12.2-year follow-up, all-cause death was observed in 836 (45.8%) participants. Impaired HLFC was significantly associated with mortality (hazard ratio [HR] 1.37; 95% confidence interval [CI], 1.13–1.65). Lower social role was significantly associated with higher mortality risk in men (HR 1.38; 95% CI, 1.13–1.68). Lower IADL and intellectual activity were significantly associated with higher mortality risk in women (HR 1.50; 95% CI, 1.15–1.95 and HR 1.46; 95% CI, 1.19–1.79, respectively). The relationship between HLFC and mortality risk showed a similar tendency among cardiovascular diseases, stroke, cancer, and pneumonia.

Conclusion: Impaired HLFC was associated with a high risk of all-cause mortality among community-dwelling older people with independent BADL. In particular, social role in men and IADL and intellectual activity in women were associated with long-term mortality risk.

Background: The association between changes in estimated glomerular filtration rate (eGFR) over time and the risk of stroke remains inconclusive. We aimed to evaluate the relation of eGFR change during the China Stroke Primary Prevention Trial (CSPPT) with the risk of first stroke during the subsequent post-trial follow-up.

Methods: A total of 11,742 hypertensive participants with two eGFR measurements (median measure interval, 4.4; interquartile range, 4.2–4.6 years) and without a history of stroke from the CSPPT were included in this analysis.

Results: Over a median post-trial follow-up of 4.4 years, 729 first strokes were identified, of which 635 were ischemic, 88 were hemorrhagic, and 6 were uncertain types of strokes. Compared with those with 1 to <2% per year increase in eGFR (with the lowest stroke risk), those with an increase in eGFR of ≥4% per year had significantly increased risks of first stroke (adjusted hazard ratio [HR] 1.96; 95% confidence interval [CI], 1.10–3.50) and first ischemic stroke (adjusted HR 2.14; 95% CI, 1.17–3.90). Similarly, those with a decline in eGFR of ≥5% per year also had significantly increased first stroke (adjusted HR 2.13; 95% CI, 1.37–3.31) and first ischemic stroke (adjusted HR 1.89; 95% CI, 1.19–3.02) risk. However, there was no significant association between eGFR change and first hemorrhagic stroke. A similar result was found when the change in eGFR was quantified as an absolute annual change.

Conclusion: In Chinese hypertensive patients, both the decline and increase of eGFR levels were independently associated with the risks of first stroke or first ischemic stroke.

Background: Reports of mortality-associated risk factors in patients with the novel coronavirus disease 2019 (COVID-19) are limited.

Methods: We evaluated the clinical features that were associated with mortality among patients who died during hospitalization (n = 158) and those who were alive at discharge (n = 2,736) from the large-scale, multicenter, retrospective, observational cohort CLOT-COVID study, which enrolled consecutively hospitalized COVID-19 patients from 16 centers in Japan from April to September 2021. Data from 2,894 hospitalized COVID-19 participants of the CLOT-COVID study were analyzed in this study.

Results: Patients who died were older (71.1 years vs 51.6 years, P < 0.001), had higher median D-dimer values on admission (1.7 µg/mL vs 0.8 µg/mL, P < 0.001), and had more comorbidities. On admission, the patients who died had more severe COVID-19 than did those who survived (mild: 16% vs 63%, moderate: 47% vs 31%, and severe: 37% vs 6.2%, P < 0.001). In patients who died, the incidence of thrombosis and major bleeding during hospitalization was significantly higher than that in those who survived (thrombosis: 8.2% vs 1.5%, P < 0.001; major bleeding: 12.7% vs 1.4%, P < 0.001). Multivariable logistic regression analysis revealed that age >70 years, high D-dimer values on admission, heart disease, active cancer, higher COVID-19 severity on admission, and development of major bleeding during hospitalization were independently associated with a higher mortality risk.

Conclusion: This large-scale observational study in Japan identified several independent risk factors for mortality in hospitalized patients with COVID-19 that could facilitate appropriate risk stratification of patients with COVID-19.