Published papers

Background: myopia prevalence is high among Japanese schoolchildren, but the underlying causes are unclear. Objective: To examine the distributions of ocular biometry and refraction and their associations with lifestyle variables among Japanese schoolchildren. Methods: This cross-sectional school-based study included 2140 children aged 3–14 years in Tokyo, Japan, and evaluated the distributions under non-cycloplegic conditions and the associated environmental factors. Results: The prevalence of spherical equivalent (SE) ≤−0.75 diopter among preschoolers (aged 3–6 years), elementary school students (aged 6–11 years), and junior high school students (aged 12–14 years) was 49.7%, 72.4%, and 87.7%, respectively. Multiple linear regression analyses showed that the time spent using digital devices was associated positively with lens thickness (β = 0.010; p < 0.050) but not SE, axial length, or vitreous chamber depth. The time spent reading was associated negatively with lens thickness (β = −0.012; p < 0.050), SE (β = −0.152; p < 0.010), axial length (β = 0.110; p < 0.001), and vitreous chamber depth (β = 0.110; p < 0.001). Conclusions: The data indicated that almost half of preschoolers may be myopic. The association with the lens thickness differed depending on the type of near work performed.

Importance: Given the estimates of increasing prevalence of myopia, especially in Asia, it is important to determine the current prevalence of myopia among populations of schoolchildren in Japan. Objective: To investigate the current prevalence rate of myopia and the association between environmental factors and myopia in Japanese schoolchildren. Design, Setting, and Participants: This cross-sectional study assessed 1478 participants, including 726 elementary school students and 752 junior high school students, at 2 schools in Tokyo, Japan, who underwent eye examinations from April 1 to May 31, 2017, that included measurement of the refractive errors by autorefractometry with noncycloplegic refraction and ocular biometric factors. After excluding those who had been treated with atropine or orthokeratology (n = 11), had a history of eye disease (n = 2), had no parental consent (n = 41), and were absent (n = 8), 1416 schoolchildren were analyzed. Main Outcomes and Measures: The primary outcome was the prevalence of myopia and high myopia. Secondary outcomes were environmental factors that were associated with myopia. Results: A total of 1416 schoolchildren (mean [SD] age, 10.8 [2.7] years; 792 [55.9%] male) were studied. The prevalence rates of myopia (spherical equivalent ≤-0.5 diopters [D]) were 76.5% (95% CI, 73.4%-79.7%) among the elementary school students and 94.9% (95% CI, 93.3%-96.5%) among the junior high school students. The prevalence rates of high myopia (spherical equivalent ≤-6.0 D) were 4.0% (95% CI, 2.5%-5.4%) among the elementary school students and 11.3% (95% CI, 8.8%-13.7%) among the junior high school students. The prevalence rates of high myopia classified based on axial length of 26.0 mm or longer were 1.2% (95% CI, 0.4%-2.0%) among elementary school students and 15.2% (95% CI, 12.5%-17.8%) among junior high school students. Multiple regression analysis showed that higher-order aberrations and dry eye disease were associated with refractive error in elementary school students (spherical aberration: β = 6.152; 95% CI, 3.161-9.143; P <.001; dry eye disease: β = -0.626; 95% CI, -1.189 to -0.063; P =.03) and with axial length in junior high school students (spherical-like aberration: β = 26.546; 95% CI, 18.708-34.385; P <.001; dry eye disease: β = 0.354; 95% CI, 0.131-0.578; P <.002). Conclusions and Relevance: Although the use of noncycloplegic autorefraction with a cutoff of -0.50 D could lead to overestimation of results, these findings suggest that the current prevalence rates of myopia among elementary and junior high school students in Asia are high, especially if the results from these 2 schools are generalizable to all schoolchildren in Japan and Asia..

In Japan, approximately 20% of women in their twenties are underweight (BMI < 18.5 kg/m2), representing one of the highest prevalences among developed nations. Underweight and undernutrition are associated with decreased bone mass, menstrual abnormalities, impaired glucose tolerance, sarcopenia-like changes, and systemic symptoms including depression and fatigue, significantly impacting health from young adulthood through the life course. This situation is influenced by complex factors including the societal internalization of thinness ideals, social media and mass media influences, the off-label use of GLP-1 receptor agonists, and socioeconomic factors such as poverty. However, while current healthcare and screening systems have advanced in addressing obesity, systematic approaches to underweight remain inadequately developed. Based on discussions by an expert working group established by the Japan Society for the Study of Obesity in collaboration with multiple related academic societies, this paper proposes a novel disease concept: Female Underweight/Undernutrition Syndrome (FUS). FUS encompasses the diverse physical and psychological health disorders arising from underweight or undernutrition, aiming to establish clear diagnostic criteria and frameworks for early detection and preventive intervention. Comprehensive measures are required, including stigma prevention, collaboration with educational and industrial sectors, integration into health screening systems, and addressing underlying social determinants. Through the proposal of FUS, we anticipate progress toward comprehensive interventions addressing the societal challenges surrounding women's health and body image.

A 43-year-old woman with genetically confirmed glycogen storage disease type Ib was suspected to have left breast cancer. Fluorodeoxyglucose-positron emission tomography showed high fluorodeoxyglucose accumulation in the whole liver as well as left mammary gland. We consider that high fluorodeoxyglucose accumulation in the liver of patients with glycogen storage disease type I is caused by impaired glucose-6-phosphate metabolism due to the congenital deficiency of glucose-6-phosphatase activities in hepatocytes. This study describes fluorodeoxyglucose-positron emission tomography as a potential alternative tool to diagnose glycogen storage disease type I functionally.

Aim: During the coronavirus disease 2019 pandemic, the governments of many countries responded to high levels of infection with lockdowns. As a result, some children were reported to experience weight gain. The aim of the present study was to examine the impact of school closures on body mass index (BMI) in Japanese children. Methods: This was a retrospective study of students enrolled in the participating schools (6- to 11-year-old elementary school students and 12- to 14-year-old junior high school students) between 2015 and 2020. Using school health check-up data, annual changes in the BMI standard deviation score (ΔBMI-SDS) were calculated. We compared ΔBMI-SDS in 2019–2020 with the corresponding control years. Results: 19 565 children with complete data were included in the analysis. Median ΔBMI-SDS in 2019–2020 were 0.24–0.35 in elementary school boys, 0.10–0.13 in junior high school boys, −0.02 to 0.15 in elementary school girls and −0.14 to −0.10 in junior high school girls. In comparison with every control year, ΔBMI-SDS in 2019–2020 were significantly higher in elementary school boys (control years: −0.07 to 0.14) and junior high school boys (control years: −0.04 to 0.06), and significantly lower in junior high school girls (control years: −0.06 to 0.09). Conclusion: BMI-SDS increased significantly in elementary and junior high school boys, but decreased significantly in junior high school girls. The pandemic appears to have had an impact on Japanese children that was different from other countries.

Obesity-related hypertension is increasing in Japan, but limited evidence exists on how weight change in early adulthood affects blood pressure (BP). We aimed to investigate the longitudinal relationship between weight change and BP among Japanese university students. We analyzed data from 20,929 first-year students who underwent annual health checkups at Keio University from 2013 to 2016 and again three years later. Students were categorized into seven groups by percentage weight change. Associations between weight change and changes in systolic and diastolic BP (ΔSBP/ΔDBP) were examined using sex-stratified analyses and restricted cubic spline (RCS) models. Weight gain was linked to BP increases, while weight loss was associated with BP reductions. In men, weight gain >3% increased SBP and DBP, and weight loss >3% reduced SBP; DBP reduction was evident with >10% weight loss. In women, SBP increased with weight gain >5%, and DBP increased with >10% weight gain; SBP decreased with >10% weight loss. RCS models revealed nonlinear, dose-dependent associations with sex-specific patterns. Absolute BMI was also positively associated with BP, with inflection points consistently observed at BMI 21.6 kg/m² for SBP and DBP in women, and for DBP in men. Even moderate weight changes over three years significantly influenced BP, with SBP being more responsive than DBP and stronger effects observed in men. These findings suggest that even during shorter periods in young adults, body weight change has a high impact on BP and highlight the potential public health benefits of strategies aimed at preventing weight gain throughout adulthood.

Background: Low birth weight (LBW) is a risk factor for chronic kidney disease (CKD) in later life and is becoming increasingly common in developed countries, including Japan. Furthermore, a serial decrease in birth weight has been associated with an increasing prevalence of CKD stage 2 in male Japanese adolescents. Sex-specific differences affect CKD susceptibility, and the association between birth weight and CKD in women, has not been elucidated. In this study, we investigated the sex-specific effect of LBW on renal function. Methods: Annual cross-sectional data of 2417 Japanese adolescents (males 1736; females 681), aged 15–16 years, were evaluated over 8 years (2007–2014). Results: Over the study period, mean birth weights decreased significantly in males (p < 0.01) and females (p < 0.05). Furthermore, both sexes showed significant decrease in estimated glomerular filtration rates corresponding to the birth weight reduction. The prevalence of CKD stage 2 also increased in males (from 26.0 to 32.4%, p < 0.01) and females (from 6.3 to 18.5%, p < 0.05). The incidence of CKD stage 2 was significantly related to history of LBW (males: odds ratio 1.73; 95% confidence interval 1.06–2.80; p < 0.05; females: odds ratio 3.29; 95% confidence interval 1.25–8.02; p < 0.05). Conclusions: Our data revealed that renal function and birth weight have decreased over time, in healthy Japanese adolescents. In view of the recent declining trend demonstrated by birth weight in Japan, we speculate that the prevalence of CKD might increase in the future.

Context: Child health statistics are a critical component of child health assessment. However, the importance of nationally representative data on growth is not well recognised for Japanese children. Objective: The aim of this paper is to review the national growth surveys for Japanese children and to discuss the clinical use of the national growth reference values and growth curves. Methods: There are five governmental organisations surveying health and growth in Japanese children. Based on these studies, several aspects of the current governmental policy on child growth assessment have been examined. This review focussed on national anthropometric studies reported by Japanese investigators in English for international readers to understand Japanese issues. Results: A variety of growth reference curves have been developed since the early 1980s in Japan. However, these references have several limitations: incomplete data for both infants and young adults, limited description of socio-economic factors and continued governmental use of weight-for-height rather than BMI. Conclusion: Japanese child health statistics use measures that are applicable only to Japanese children.

Background: Patterns of blood pressure (BP) change from early adolescence to young adulthood have not been well-described. The objective of this study was to examine the predictive value of pediatric BP classification on BP change and identify subpopulations with large BP increases during adolescence and early adulthood. Methods: Baseline data were obtained from medical checkups of Japanese adolescents aged 12–13 years in 2009 or 2010 and subsequent BP values were followed for a 9-year period. Mixed-effects models were used to estimate the effects of baseline factors on subsequent BP changes. Results: Hypertensive and elevated BP group consistently had higher BP values than normal BP group throughout the observation period. Multivariate mixed-effects model analyses revealed group-by-time interactions between systolic BP change and BP category in males and uric acid category in females, and between diastolic BP change and white blood cell count in males and obesity and high-density lipoprotein cholesterol in females; however, these factors had limited effects on the rate of BP increase, indicating that they are not suitable as clinical predictors of BP increase. Conclusions: Pediatric BP category predicted BP values, but there was no factor that identified subpopulations with large BP increases in adolescence and early adulthood. Impact: Blood pressure category in the American Academy of Pediatrics clinical practice guideline at age 12–13 years predicted subsequent blood pressure values during adolescence and early adulthood.No baseline factor that identified a subpopulation with large increase in blood pressure during adolescence and early adulthood in clinical practice was found.Our study contributes to the existing literature by demonstrating the usefulness of the American Academy of Pediatrics clinical practice guideline for blood pressure classification in a Japanese population.

For preterm and very low birthweight infants, the mother’s own milk is the best nutrition. Based on the latest information for mothers who give birth to preterm and very low birthweight infants, medical staff should encourage and assist mothers to pump or express and provide their own milk whenever possible. If the supply of maternal milk is insufficient even though they receive adequate support, or the mother’s own milk cannot be given to her infant for any reason, donor human milk should be used. Donors who donate their breast milk need to meet the Guideline of the Japan Human Milk Bank Association. Donor human milk should be provided according to the medical needs of preterm and very low birthweight infants, regardless of their family’s financial status. In the future, it will be necessary to create a system to supply an exclusive human milk-based diet (EHMD), consisting of human milk with the addition of a human milk-derived human milk fortifier, to preterm and very low birthweight infants.

2008年に「学校のアレルギー疾患に対する取り組みガイドライン」、ならびに学校生活管理指導表(アレルギー疾患用、以下、指導表)の運用が開始され8年が経過するが、学校に提出された指導表の記載内容から中学生の食物アレルギーの実態について検討した報告は少ない。今回我々は、学校健康診断時に収集した食物アレルギーに関する情報、および提出された指導表から中学生の食物アレルギーの実態、ならびに食物アレルギーに関する取り組みに対する課題を検討した。2015年および2016年に東京都および神奈川県内の学校給食を実施していない中学校3校の中学1年生1,318人に、入学時に保護者に対して食物アレルギーの既往に関するアンケート調査を実施した。食物アレルギーを申告した生徒を対象として、学校健康診断時に問診票を用いて聞き取り調査を行い、アナフィラキシーの既往、エピネフリン自己注射薬使用(以下、エピペン)の適応となる症状の既往、多品目にわたる原因食物を申告した者を対象に、学校生活管理指導表の提出を求めた。食物アレルギーを申告した生徒は117人(8.8%)で、このうち医師による診断を受けている者は81人(73%)であった。指導表を提出した37人(2.8%)のうち、新たに診断された6人を含む20人(1.5%)がアナフィラキシーの既往ありと診断された。食物アレルギーを申告した中学生の一部は、医師による診断を受けておらず、加えて、食物アレルギーの症状を過小評価していることが示唆された。(著者抄録)

2016年度の小中学校健康診断において実施した運動器検診の成績評価を通して、運動器検診を実施する際の要点を検討した。小学生1280人、中学生1963人を対象とした2016年度学校健康診断における運動器検診の結果、運動器問診票では小学生10.0%、中学生17.1%において運動器の所見が認められ、学校医による診察では小学生0.4%、中学生2.2%において脊柱側彎が疑われた。医療機関への受診状況等を検討し、小学生0.4%、中学生2.0%が整形外科医による二次検診の対象となった。運動器検診を実施する際の要点として、以下があげられる。(1)運動器検診の目的は、使い過ぎによる運動器疾患および脊柱側彎の有無を診断することにあり、柔軟性やバランス感覚不足などの評価は目的に含まない。(2)運動器問診票(運動器保健調査票)では、運動器の問題点に加えて医療機関への受診状況を同時に調査することが重要である。(3)学校健康診断では、学校医は全員を対象に胸郭変形の視診および脊柱側彎の検査を実施する必要がある。(4)運動器二次検診は、成長期の子どもの運動器疾患について診療経験が豊富な整形外科医に依頼し、事前に運動器検診の趣旨を伝えておくことが重要である。(5)運動器疾患の早期発見、早期診断には、運動器検診だけでなく、教育啓発活動による運動器疾患に関する知識の普及が必須である。(著者抄録)

小学生、中学生、高校生における川崎病既往者増加の実態を明らかにするため、川崎病全国調査成績から、小・中・高校生における川崎病既往者の推定頻度を算出し、年次変化および学校心臓検診における川崎病既往者への対策を検討した。小・中・高校生における川崎病既往者の推定頻度は、年次を追うごとに増加しており、2017年度では小学1年生1.32%、中学1年生0.99%、高校1年生0.82%に達し、学年が低い者ほど川崎病既往者の頻度が高かった。心臓後遺症が出現した川崎病既往者の推定頻度は、小学生では横ばいに推移する一方で、中学生および高校生では減少を認め、2017年度には小・中・高校生(0.038%・0.040%・0.038%)がほぼ横並びとなった。川崎病既往者では、学年が上位の者ほど心臓後遺症が出現した頻度が高かった。小・中・高校生の心臓後遺症が出現した川崎病既往者では、約半数に冠動脈病変が残存している可能性があり、その中には急性冠症候群を起こすリスクの高い者も存在する。小・中・高校生の学校心臓検診では、増加している川崎病既往者を確実に把握し、同時に心臓後遺症の精査状況についての確認を徹底することが必要である。(著者抄録)

インフルエンザ対策では、インフルエンザ流行の増幅因子である学校内での流行をいかに抑えるかが課題である。そのためには、学校内でのインフルエンザ流行状況の把握とワクチンの集団免疫効果の評価が必要であるが、学校における大規模かつ経時的なデータはこれまでにない。本研究では、のべ5,114人の小学生を対象に2010-2015年度6シーズンの全例観察コホート研究を実施し、インフルエンザ罹患率、インフルエンザワクチン接種率、ワクチン有効率、インフルエンザ流行時期の学級閉鎖日数を算出した。6シーズンの平均はインフルエンザ罹患率34%、ワクチン接種率78%、ワクチン有効率17%(低学年:11%、高学年:23.7%)、学級閉鎖日数21日/年であった。インフルエンザ流行株にB型の占める割合は多いシーズンでは、罹患率上昇、有効率低下、学級閉鎖日数増加傾向を認めた。小学生のインフルエンザ罹患率は一般対象に比べて高く、またワクチン有効率は低いことから、学校がインフルエンザ流行の増幅因子であることが示唆された。一方で、学級閉鎖日数はワクチン接種率が低かった過去のシーズンに比べ短縮していることから、ワクチンの集団免疫効果の存在が示唆された。学校におけるワクチンの集団免疫効果はワクチン有効率単独での判定は困難であり、罹患率や学級閉鎖日数等を含めた包括的な評価が必要であること考えられる。(著者抄録)