Background: Breastfeeding is said to prevent overweight and obesity in childhood but the evidence about its long-term impact on body size into adolescence and adulthood is scarce. We sought to examine the association between feeding types and subsequent physical size at the ages of 3, 6, 12, and 22 years.

Methods: The Ibaraki Children’s Cohort (IBACHIL) Study, which began in 1992, involved a cohort of 4,592 Japanese children from 87 communities of a single prefecture whose parents answered health questionnaires about their child’s health and life habits at the age of 3 years. Follow-up questionnaires were distributed to the same cohort when they were 6, 12, and 22 years old. Self-reported height and weight, body mass index (BMI), and overweight status at ages of 3 (n = 4,290), 6 (n = 1,999; proportion of participants analyzed = 47%), 12 (n = 2,227; 52%), and 22 (n = 1,459; 34%) years were compared according to feeding type (breastfeeding, formula feeding, and mixed feeding) during infancy.

Results: At the age of 3 years, multivariable adjusted-mean weight and prevalence of overweight were less for breastfed children than those formula-fed in both boys (weight: 14.6 kg vs 14.7 kg, P = 0.07, overweight: 6.3% vs 9.3%, P = 0.03) and in girls (14.0 kg vs 14.2 kg, P = 0.01 and 10.4% vs 13.6%, P = 0.06). However, there were no statistically significant differences in weight, BMI, and overweight at the ages of 6, 12, and 22 years according to feeding type.

Conclusion: Breastfeeding may prevent overweight in childhood, but its impact is not significant in adolescence and adulthood.

Background: To provide a better healthcare system for patients with mitochondrial diseases, it is important to understand the basic epidemiology of these conditions, including the number of patients affected. However, little information about them has appeared in Japan to date.

Methods: To gather data of patients with mitochondrial diseases, we estimated the number of patients with mitochondrial diseases from April 2018 through March 2019 using a national Japanese health care claims database, the National Database (NDB). Further, we calculated the prevalence of patients, and sex ratio, age class, and geographical distribution.

Results: From April 2018 through March 2019, the number of patients with mitochondrial diseases was 3,629, and the prevalence was 2.9 (95% confidence interval [CI], 2.8–3.0) per 100,000 general population. The ratio of females and males was 53 to 47, and the most frequent age class was 40–49 years old. Tokyo had the greatest number of patients with mitochondrial diseases, at 477, whereas Yamanashi had the fewest, at 13. Kagoshima had the highest prevalence of patients with mitochondrial diseases, 8.4 (95% CI, 7.1–10.0) per 100,000 population, whereas Yamanashi had the lowest, 1.6 (95% CI, 0.8–2.7).

Conclusion: The number of patients with mitochondrial diseases estimated by this study, 3,269, was more than double that indicated by the Japanese government. This result may imply that about half of all patients are overlooked for reasons such as low severity of illness, suggesting that the Japanese healthcare system needs to provide additional support for these patients.

Background: There is limited evidence regarding the relationship between Diabetes mellitus (DM) in middle age and mild cognitive impairment after a follow-up. Therefore, we investigated the relationship between fasting blood glucose (FBG) levels in middle age and cognitive function assessed using the Japanese version of the Montreal Cognitive Assessment (MoCA-J) in later life, following over 15 years of follow-up in the Aichi Workers’ Cohort Study in Japan.

Methods: Participants were 253 former local government employees aged 60–79 years in 2018 who participated in a baseline survey conducted in 2002. Using baseline FBG levels and self-reported history, participants were classified into the normal, impaired fasting glucose (IFG) and, and DM groups. Total MoCA-J score ranges from 0 to 30, and cognitive impairment was defined as MoCA-J score ≤25 in this study. A general linear model was used to estimate the mean MoCA-J scores in the FBG groups, adjusted for age, sex, educational year, smoking status, alcohol consumption, physical activity, body mass index, systolic blood pressure, total cholesterol, and estimated glomerular filtration rate.

Results: The mean MoCA-J score in the total population was 25.0, and the prevalence of MoCA-J score ≤25 was 49.0%. Multivariable-adjusted total MoCA-J scores were 25.2, 24.8, and 23.4 in the normal, IFG, and DM groups, respectively. The odds ratio of MoCA-J score ≤25 in the DM group was 3.29.

Conclusion: FBG level in middle age was negatively associated with total MoCA-J scores assessed later in life, independent of confounding variables.

Background: Impact of immeasurable time bias (IMTB) is yet to be examined in self-controlled designs.

Methods: We conducted case-crossover, case-time-control, and case-case-time-control analyses using Korea’s healthcare database. Two empirical examples among elderly patients were used: 1) benzodiazepines-hip fracture; 2) benzodiazepines-mortality. For cases, the date of hip fracture diagnosis or death was defined as the index date, and the inherited date of their matched cases for controls or future cases. Exposure was assessed in the 1–30 day (hazard) and 61–90 day (control) windows preceding the index date. A non-missing exposure setting included in- and outpatient prescriptions and the pseudo-outpatient setting included only the outpatients. Conditional logistic regression was done to estimate odds ratios (ORs) with 95% confidence intervals (CIs), where the relative difference in OR among the two settings was calculated to quantify the IMTB.

Results: The IMTB had negligible impacts in the hip fracture example in the case-crossover (non-missing exposure setting OR 1.27; 95% CI, 1.12–1.44; pseudo-outpatient setting OR 1.21; 95% CI, 1.06–1.39; magnitude 0.05), case-time-control (OR 1.18; 95% CI, 0.98–1.44; OR 1.13; 95% CI, 0.92–1.38; 0.04, respectively), and case-case-time-control analyses (OR 0.99; 95% CI, 0.80–1.23; OR 0.94; 95% CI, 0.75–1.18; 0.05, respectively). In the mortality example, IMTB had significant impacts in the case-crossover (non-missing exposure setting OR 1.44; 95% CI, 1.36–1.52; pseudo-outpatient setting OR 0.72; 95% CI, 0.67–0.78; magnitude 1.00), case-time-control (OR 1.38; 95% CI, 1.26–1.51; OR 0.68; 95% CI, 0.61–0.76; 1.03, respectively), and case-case-time-control analyses (OR 1.27; 95% CI, 1.15–1.40; OR 0.62; 95% CI, 0.55–0.69; 1.05, respectively).

Conclusion: Although IMTB had negligible impacts on the drug’s effect on acute events, as these are unlikely to be accompanied with hospitalizations, it negatively biased the drug’s effect on mortality, an outcome with prodromal phases, in the three self-controlled designs.

Background: Few cohort studies have used multiple surveys of screening attendance to simultaneously evaluate the effectiveness of fecal occult blood test (FOBT) and colonoscopy.

Methods: We analyzed data of 30,381 middle-aged Japanese adults from a population-based prospective cohort study. Information on FOBT and colonoscopy was obtained from three questionnaire surveys (every 5 years). We classified the subjects into three groups: the FOBT (15,649 subjects), screening colonoscopy (2,407 subjects), and unscreened (12,325 subjects) groups. We used the unscreened group as the reference group to compare the mortality and incidence of colorectal cancer (CRC).

Results: During the 14-year follow-up, 64, 12, and 104 CRC deaths were identified in the FOBT, screening colonoscopy, and unscreened groups, respectively. The risk of CRC death reduced with increasing the number of FOBTs (P for trend = 0.02) and was reduced by 44% in the subjects screened twice or thrice using FOBT (hazard ratio [HR] 0.56; 95% confidence interval [CI], 0.33–0.94). Significant decreases were seen for the incidence of CRC but not seen for the incidence of non-advanced CRC in the FOBT group. Concerning the screening colonoscopy, subjects screened at the start of follow-up showed a 69% reduced risk of CRC death (HR 0.31; 95% CI, 0.10–0.9996). Significant decreases were also seen for the incidence of CRC and non-advanced CRC in the subjects screened at the start of follow-up.

Conclusion: FOBT, depending on the number of FOBTs, and colonoscopy, depending on recency, reduced the risk of death due to CRC and the incidence of CRC.

Background: In 2012, the Korean government expanded dental insurance for the elderly to promote improved access to dental care. We examined the causal effect of this policy on dental care needs, focusing on low-income older adults.

Methods: We compared data before and after policy implementation using double difference (DD) and triple difference (DDD) analyses. We used the nationally representative data from the Korea National Health and Nutrition Examination Survey from 2010 and 2016–2018. Individuals aged ≥65 years were included in the treatment group, and individuals aged <65 years were included in the control group.

Results: Dental insurance expansion was associated with a paradoxical increase in perceived unmet dental needs among elderly individuals (8.8 percentage points increase, 95% CI: 4.7 to 13.0). However, there were improvements in dental prosthetics outcomes (denture wearing [4.0 percentage points, 95% CI: 0.2 to 7.9] and dental implants [5.0 percentage points, 95% CI: 2.1 to 7.9]; P < 0.01). Upon analyzing low-income elderly individuals using DDD analysis, we found that the insurance expansion led to a 21.6% smaller increase in unmet dental needs among low-income adults, compared to high-income adults (95% CI, −35.0 to −8.5; P < 0.01).

Conclusion: Dental insurance expansion in South Korea resulted in improvements in access to dental prosthetic services overall. It also led to a smaller increase in unmet dental needs among low-income older adults, compared to high-income adults.