Background We set out to investigate the reliability and validity of the Japanese version of the CDC core healthy day measures assessing health‐related quality of life (CDC HRQOL‐4) in Japanese workers. Methods This cross‐sectional study was conducted among 1360 Japanese workers of one Japanese company located in Kyushu. Cronbach's alpha was calculated to evaluate the internal consistency of CDC HRQOL‐4 items. The concurrent validity was tested by assessing whether the CDC HRQOL‐4 items correlated well with the corresponding domains of the SF‐8 and the overall WFun score. The construct validity was tested by assessing the ability of the CDC HRQOL‐4 to discriminate groups with and without any current disease, pain, mental problem, and sleeping disorder. Results Cronbach's alpha for three of the four CDC HRQOL‐4 items was 0.80, which is greater than the minimal standard (0.70) recommended for internal consistency reliability. Correlation coefficients ranging from 0.25 to 0.67 were obtained between CDC HRQOL‐4 items and the SF‐8 domains and WFun score. Workers with any current disease, mental problem, pain or sleeping disorder reported higher numbers of unhealthy days, and a higher odd of poor health than those without such problems. Japanese version of the CDC HRQOL‐4 shows a good concurrent validity with the SF‐8 and the WFun tool and good construct validity among Japanese workers in the current study. Conclusions Japanese version of the CDC HRQOL‐4 is a reliable and valid instrument that may be used to assess overall health and physically and mentally unhealthy days in Japanese workers.

Background To combat coronavirus disease 2019 (COVID-19), many countries have used contact tracing apps, including Japan’s voluntary-use contact-confirming application (COCOA). The current study aimed to identify industry and workplace characteristics associated with the downloading of this COVID-19 contact tracing app. Methods This cross-sectional study of full-time workers used an online survey. Multiple logistic regression analysis was used to evaluate the associations of industry and workplace characteristics with contact tracing app use. Results Of the 27,036 participants, 25.1% had downloaded the COCOA. Workers in the public service (adjusted odds ratio [aOR] = 1.29, 95% confidence interval [CI] 1.14–1.45) and information technology (aOR = 1.38, 95% CI 1.20–1.58) industries were more likely to use the app than were those in the manufacturing industry. In contrast, app usage was less common among workers in the retail and wholesale (aOR = 0.87, 95% CI 0.76–0.99) and food/beverage (aOR = 0.81, 95% CI 0.70–0.94) industries, but further adjustment for company size attenuated these associations. Workers at larger companies were more likely to use the app. Compared with permanent employees, the odds of using the app were higher for managers and civil servants but lower for those who were self-employed. Conclusions Downloading of COCOA among Japanese workers was insufficient; thus, the mitigating effect of COCOA on the COVID-19 pandemic is considered to be limited. One possible reason for the under-implementation of the contact tracing app in the retail and wholesale and food/beverage industries is small company size, as suggested by the fully adjusted model results. An awareness campaign should be conducted to promote the widespread use of the contact tracing app in these industries.

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.

International immigration into Japan is increasing. It would make sense that investigating the health status of immigrants would be associated with improvements in their health and would be beneficial in building a complete social security system in which minorities can live safely and securely. The objective of this study is to describe the health status of immigrants in Japan and to explore the association between self-rated health status and employment status. As a result, half of those surveyed had some health problem, particularly a lot of mental stress. We did not find a significant relationship between self-rated health status and employment status, but it seems that people who stay in Japan 5 years or more tend to have poor self-rated health status. The factors associated with poor self-rated mental health status were being a non-employee, and having visited a hospital 1 time or more during the past 12 months. A system of mental stress care would be the most necessary health care for international students in Japan.

Objectives: To combat coronavirus disease 2019 (COVID-19), many countries have used contact tracing apps, including Japan's voluntary-use contact-confirming application (COCOA). The current study aimed to identify industry and workplace characteristics associated with the use of this COVID-19 contact tracing app. Methods: This cross-sectional study of full-time workers used an online survey. Multiple logistic regression analysis was used to evaluate the associations of industry and workplace characteristics with contact tracing app use. Results: Of the 27,036 participants, 25.1% had downloaded the COCOA. Workers in the public service (adjusted odds ratio [aOR] = 1.29, 95% confidence interval [CI]: 1.14-1.45) and information technology (aOR = 1.38, 95% CI: 1.20-1.58) industries were more likely to use the app than were those in the manufacturing industry. In contrast, app usage was less common among workers in the retail and wholesale (aOR = 0.87, 95% CI: 0.76-0.99) and food/beverage (aOR = 0.81, 95% CI: 0.70-0.94) industries, but further adjustment for business size attenuated these associations. Workers at larger companies were more likely to use the app. Compared with permanent employees, the odds of using the app were higher for managers and civil servants but lower for those who were self-employed. Conclusions: One possible reason for the under-implementation of the contact tracing app in the retail and wholesale and food/beverage industries is small business size, as suggested by the fully adjusted model results. An awareness campaign should be conducted to promote the widespread use of the contact tracing app in these industries.