This study aimed to identify factors associated with the prevalence and severity of menstrual-related symptoms. The protocol was registered in PROSPERO (CRD42021208432). We conducted literature searches of PubMed and Ichushi-Web and used the Jonna Briggs Institute critical appraisal checklist to assess the quality. Of the 77 studies included in the meta-analysis, significant odds ratios (ORs) were obtained for eight factors associated with primary dysmenorrhea (PD): age ≥ 20 years (OR: 1.18; 95% confidence interval [CI]: 1.04–1.34), body mass index (BMI) < 18.5 kg/m² (OR: 1.51; 95% CI: 1.01–2.26), longer menstrual periods (OR: 0.16; 95% CI: 0.04–0.28), irregular menstrual cycle (OR: 1.28; 95% CI: 1.13–1.45), family history of PD (OR: 3.80; 95% CI: 2.18–6.61), stress (OR: 1.88; 95% CI: 1.30–2.72), sleeping hours < 7 h (OR: 1.19; 95% CI: 1.04–1.35), and bedtime after 23:01 (OR: 1.30; 95% CI: 1.16–1.45). Two factors were associated with severity of PD (moderate vs. severe): BMI < 18.5 kg/m² (OR: 1.89; 95% CI: 1.01–3.54) and smoking (OR: 1.94; 95% CI: 1.08–3.47). PD severity (mild vs. severe) and prevalence of premenstrual syndrome were associated with BMI < 18.5 kg/m² (OR: 1.91; 95% CI: 1.04–3.50) and smoking (OR: 1.86; 95% CI: 1.31–2.66), respectively. The identified risk factors could be utilized to construct an appropriate strategy to improve menstrual symptoms and support women’s health.

Background: The Longevity Improvement & Fair Evidence (LIFE) Study, which was launched in 2019, is a multi-region community-based database project that aims to generate evidence toward extending healthy life expectancy and reducing health disparities in Japan. Herein, we describe the LIFE Study’s design and baseline participant profile.Methods: Municipalities participating in the LIFE Study provide data from government-administered health insurance enrollees and public assistance recipients. These participants cover all disease types and age groups. Centered on healthcare claims data, the project also collects long-term care claims data, health checkup data, vaccination records, residence-related information, and income-related information. The different data types are converted into a common data model containing five modules (health care, long-term care, health checkup, socioeconomic status, and health services). We calculated the descriptive statistics of participants at baseline in 2018.Results: The LIFE Study currently stores data from 1,420,437 residents of 18 municipalities. The health care module contains 1,280,756 participants (mean age: 65.2 years), the long-term care module contains 189,069 participants (mean age: 84.3 years), and the health checkup module contains 274,375 participants (mean age: 69.0 years). Although coverage and follow-up rates were lower among younger persons, the health care module includes 74,151 children (0–19 years), 273,157 working-age adults (20–59 years), and 933,448 older persons (≥60 years).Conclusion: The LIFE Study provides data from over 1 million participants and can facilitate a wide variety of life-course research and cohort studies. This project is expected to be a useful platform for generating real-world evidence from Japan.

The most powerful earthquake ever recorded in Japan, with a magnitude of 9.0 on the Richter scale, struck the northeast region of Japan on March 11, 2011 ( Figure 1A ).^1,2 Earthquakes are known to increase the risk of sudden cardiac arrest.³ Using a nationwide population-based database, we assessed the association between this earthquake and the occurrence of out-of-hospital cardiac arrest of presumed cardiac origin.^4,5