Background: Tobacco exposure during pregnancy is associated with several adverse outcomes in infants. We investigated the association between tobacco exposure during pregnancy (both active and second-hand) and various infections in infants up to 1 year.

Methods: This prospective cohort study used a fixed dataset (jecs-an-20180131) from the Japan Environment and Children’s Study of registered births in Japan during 2011–2014 that included 104,065 fetal records from enrolled pregnant women. Based on the participants’ responses to the questionnaire on smoking status, mothers were first divided into “never smoked,” “quit smoking,” and “current smoker” groups and then into “no second-hand smoking (SHS)” and “SHS” groups. Infectious diseases included central nervous system infection, otitis media (OM), upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), gastroenteritis (GI), and urinary tract infection. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated using logistic regression analysis and adjusted for maternal, socioeconomic, and postnatal confounding factors.

Results: Among the 73,205 newborns enrolled, multivariable analysis revealed that the aOR of LRTI and GI was 1.20 (95% CI, 1.07–1.33) and 1.18 (95% CI, 1.04–1.35), respectively, for the “current smoker with/without SHS” group compared with the “never smoked without SHS” group. “Quit smoking without SHS” was not associated with the risk of LRTI. SHS was associated with an increased risk of OM, URTI, LRTI, and GI, especially with LRTI and GI.

Conclusion: Exposure to tobacco smoke during pregnancy was associated with an increased risk of OM, URTI, LRTI, and GI in infants during their first year of life.

Background: Recent literature suggest the effect of maternal smoking on risk of hypertensive disorders in pregnancy (HDP) and preeclampsia may differ by ethnicity; however, studies on Asians are limited.

Methods: We investigated the association of maternal smoking with HDP and preeclampsia using a common analysis protocol to analyze the association in six birth cohorts participating in a Japanese consortium of birth cohorts (JBiCC). Results were compared with-published results from cohorts not included in this consortium, and, where possible, we produced a meta-analysis including these studies.

Results: Meta-analysis of four cohort studies including 28,219 participants produced an odds ratio (OR) of 1.24 (95% confidence interval [CI], 0.88–1.87) for the effect of smoking beyond early pregnancy compared to women who did not smoke during pregnancy. These results combined with those from the Japan Environment and Children’s Study (JECS) yielded an OR of 1.19 (95% CI, 1.00–1.43, P = 0.056). Meta-analysis results for categories of smoking volume were insignificant, but when combined with JECS yielded an OR of 0.86 (95% CI, 0.65–1.12) for smoking 1–4 cigarettes, 1.25 (95% CI, 0.98–1.60) for smoking 5–9 cigarettes, and 1.27 (95% CI, 1.04–1.54) for smoking 10 or more cigarettes per day. All effects were insignificant for preeclampsia.

Conclusion: Our results suggest that the protective effects of smoking longer and smoking more on HDP and preeclampsia repeatedly observed among Europeans and North Americans likely do not hold for the Japanese.

Background: In case-cohort studies with binary outcomes, ordinary logistic regression analyses have been widely used because of their computational simplicity. However, the resultant odds ratio estimates cannot be interpreted as relative risk measures unless the event rate is low. The risk ratio and risk difference are more favorable outcome measures that are directly interpreted as effect measures without the rare disease assumption.

Methods: We provide pseudo-Poisson and pseudo-normal linear regression methods for estimating risk ratios and risk differences in analyses of case-cohort studies. These multivariate regression models are fitted by weighting the inverses of sampling probabilities. Also, the precisions of the risk ratio and risk difference estimators can be improved using auxiliary variable information, specifically by adapting the calibrated or estimated weights, which are readily measured on all samples from the whole cohort. Finally, we provide computational code in R (R Foundation for Statistical Computing, Vienna, Austria) that can easily perform these methods.

Results: Through numerical analyses of artificially simulated data and the National Wilms Tumor Study data, accurate risk ratio and risk difference estimates were obtained using the pseudo-Poisson and pseudo-normal linear regression methods. Also, using the auxiliary variable information from the whole cohort, precisions of these estimators were markedly improved.

Conclusion: The ordinary logistic regression analyses may provide uninterpretable effect measure estimates, and the risk ratio and risk difference estimation methods are effective alternative approaches for case-cohort studies. These methods are especially recommended under situations in which the event rate is not low.

Background: The prevalence of overweight and obesity are well known risk factors of atherosclerotic cardiovascular disease (ASCVD). We aimed to examine the association between body mass index (BMI) and ASCVD over a 23-year follow-up in young adults. We also qualified how much of the effects of obesity on ASCVD were mediated through blood pressure, cholesterol, and glucose.

Methods: Data are from the Korean Life Course Health Study, a cohort study of 226,955 Korean young adults aged 20–39. At baseline, the participants undertook routine health assessments where their BMI was measured in 1992–1994; and the metabolic mediators including systolic blood pressure (SBP), fasting serum glucose (FSG), and total cholesterol (TC) were re-measured in 2002–2004. The main outcomes of the study include incident events of ischemic heart disease (IHD), stroke, and ASCVD between 2005 and 2015. Cox proportional model was used to calculate adjusted hazard ratios (HRs) for ASCVD.

Results: In both men and women, the direct effect of BMI on ASCVD was greater than the indirect effect. The percentage of excess HR of BMI mediated by all of the metabolic mediators, including SBP, FSG, and TC, was 45.7% for stroke and 18.7% for IHD in men and 27.5% for stroke and 17.6% for IHD in women.

Conclusion: High BMI in young adults increases the risk of metabolic mediators in their middle age, and metabolic mediators explain the adverse effects of high BMI on stroke risk than IHD risk.

Background: Previous studies have shown that socioeconomic factors are associated with cancer incidence and stage at diagnosis; however, relevant findings in Japan are limited. We examined the association between socioeconomic status and cancer incidence, stage at diagnosis, and detection status by screening, as assessed using the areal deprivation index (ADI), in population-based cancer registry data.

Methods: A total of 79,816 cases, including stomach, colorectal, lung, female breast, and cervical cancer diagnosed in Miyagi Prefecture between 2005 and 2010, were analyzed. After calculating the ADI at the place of residence in each case, we examined the association between quintiles of ADI and age-adjusted incidence rates of all stages and advanced stages by sex and site using Poisson regression analysis. The association between the ADI and the proportion of screen-detected cancers was also examined using logistic regression analysis.

Results: The age-adjusted incidence rates of all sites and lung cancer in men and lung cancer and cervical cancer in women tended to increase significantly in areas with a higher ADI. The age-adjusted incidence rates of advanced-stage cancers were significantly higher for all sites and lung cancer in both sexes, and for stomach and colorectal cancer in men. The proportion of screen-detected cancer tended to be significantly lower in areas with a higher ADI for stomach and colorectal cancer in men.

Conclusion: Our results indicate that socioeconomic disparities may affect cancer incidence and early diagnosis in Japan. These results suggest the importance of cancer control measures targeting people with low socioeconomic status in Japan.

Background: The Japan Coma Scale (JCS) is the most frequently adopted method for evaluating level of consciousness in Japan. However, no validated method for converting the JCS to the Glasgow Coma Scale (GCS) exists. The aims of the present study were to develop and validate a method to convert the JCS to GCS.

Methods: This is a multicenter retrospective analysis involving three emergency departments (EDs) in Japan. We included all adult patients who visited the ED between 2017 and 2020. The participating facilities were divided into two cohorts—one cohort to develop a table to convert the JCS to GCS (development cohort), and the other cohort to validate the conversion table (validation cohort). The conversion table of the JCS to GCS was developed based on the median values of the GCS. The outcome was the concordance rate between the JCS and GCS.

Results: We identified 8,194 eligible patients. The development cohort included 7,373 patients and the validation cohort included 821 patients. In the validation cohort, the absolute and relative concordance rates were 80.3% (95% confidence interval, 77.4–82.9%) and 93.2% (95% confidence interval, 91.2–94.8%), respectively.

Conclusion: This study developed and validated a novel method for converting the JCS to GCS. Assuming the offset by a single category between the JCS and GCS is acceptable, the concordance rate was over 90% in the general adult patient population visiting the ED. The conversion method may assist researchers to convert JCS scores into GCS scores, which are more commonly recognized among global audiences.

Background: Limited reports from prospective human studies investigated the possible role of vitamin K in the development of lung cancer although vitamin K’s anticarcinogenic activities were verified from several in vitro and in vivo studies. We investigated the associations between total vitamin K intake from food and the development of lung cancer based on this large prospective cohort study.

Methods: A validated food frequency questionnaire was used to examine vitamin K intake among 42,166 (16,341 men and 25,825 women) at the Japan Collaborative Cohort Study’s baseline (1988–1990). Hazard ratios (HRs) and 95% confidence intervals (CIs) of incident lung cancer were calculated using the Cox proportional hazard regression method based on vitamin K consumption quartiles.

Results: 430 cases (308 males and 122 women) of lung cancer were documented during a total of 564,127 person-years of follow-up (median follow-up, 14.6 years). Vitamin K consumption was shown to be inversely related to lung cancer risk; the multivariable hazard ratio [HR] for the highest versus lowest quartiles was 0.67 (95% confidence interval [CI], 0.46–0.96; P for trend = 0.010). This relationship appears to be stronger in males (HR 0.62; 95% CI, 0.40–0.96; P for trend = 0.016) than in females (HR 0.82; 95% CI, 0.42–1.61; P for trend = 0.39) (P for interaction = 0.012), and in ever smokers (HR 0.57; 95% CI, 0.36–0.91; P for trend = 0.006) than in never smokers (HR 0.79; 95% CI, 0.40–1.55; P for trend = 0.37) (P for interaction = 0.30). The individuals’ age, body mass index, or alcohol consumption status had no effect on the observed connection.

Conclusion: Vitamin K consumption reduces the risk of lung cancer. More research is needed to clarify the molecular processes behind this connection.