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This paper quantitatively investigated the historical transition of return transmission, volatility spillovers, and correlations between the US, UK, and Japanese stock markets. Applying a vector autoregressive (VAR)-dynamic conditional correlation (DCC)-multivariate exponential generalized autoregressive conditional heteroscedasticity (MEGARCH) model, we derived new evidence for four historical periods between 1984 and 2024. First, we found that the return transmission from the US to the other markets has historically become stronger, whereas recently, the return transmission from the UK to the US has disappeared. Second, we clarified that volatility spillovers from the US to the other markets have historically become stronger, whereas recently, volatility spillovers from the UK to the US have also disappeared. Third, our analyses of the historical constant correlations and DCCs revealed that stock market connectedness has gradually tightened between the US and Japan and between the UK and Japan, whereas recently, the connectedness between the US and UK has weakened. Fourth, our VAR-DCC analyses also revealed that volatility spillovers between the US, UK, and Japanese stock markets have been asymmetric. Fifth, we further showed that the skew- t errors incorporated into our VAR-DCC model are effective in estimating the dynamic stock return linkages between the US, the UK, and Japan. Finally, based on our findings, we derived many significant and beneficial interpretations and implications for historically and deeply considering return transmission, volatility spillovers, and DCCs between international stock markets. [ABSTRACT FROM AUTHOR]

Objective: To assess rates of traversing barriers to care to access optimal clinical outcomes in people with migraine internationally. Background: People in need of medical care for migraine should consult a health care professional knowledgeable in migraine management, obtain an accurate diagnosis, and receive an individualized treatment plan, which includes scientific society guideline-recommended treatments where appropriate. Methods: The Chronic Migraine Epidemiology and Outcomes-International (CaMEO-I) Study was a cross-sectional, web-based survey conducted from July 2021 through March 2022 in Canada, France, Germany, Japan, the United Kingdom, and the United States (US). Respondents who met modified International Classification of Headache Disorders, 3rd edition, criteria for migraine and had Migraine Disability Assessment Scale (MIDAS) scores of ≥ 6 (i.e., mild, moderate, or severe disability) were deemed to need medical care and were included in this analysis. Minimally effective treatment required that participants were currently consulting a health care professional for headache (barrier 1), reported an accurate diagnosis (barrier 2), and reported use of minimally appropriate pharmacologic treatment (barrier 3; based on American Headache Society 2021 Consensus Statement recommendations). Proportions of respondents who successfully traversed each barrier were calculated, and chi-square tests were used to assess overall difference among countries. Results: Among 14,492 respondents with migraine, 8,330 had MIDAS scores of ≥ 6, were deemed in need of medical care, and were included in this analysis. Current headache consultation was reported by 35.1% (2926/8330) of respondents. Compared with the US, consultation rates and diagnosis rates were statistically significantly lower in all other countries except France where they were statistically significantly higher. Total appropriate treatment rates were also statistically significantly lower in all other countries compared with the US except France, which did not differ from the US. All 3 barriers were traversed by only 11.5% (955/8330) of respondents, with differences among countries (P < 0.001). Conclusions: Of people with migraine in need of medical care for migraine, less than 15% traverse all 3 barriers to care. Although rates of consultation, diagnosis, and treatment differed among countries, improvements are needed in all countries studied to reduce the global burden of migraine. Trial registration: NA. [ABSTRACT FROM AUTHOR]