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Background: An administrative database covering a whole population such as the national database in Japan may be used to estimate the nationwide prevalence of diseases including rheumatoid arthritis (RA) when a well-validated definition of the disease is available. In Japan, the record linkage between the administrative database and medical charts in hospitals is strictly prohibited. A "hospital-based" validation study is one of few possible validation studies where claims kept inside the study hospital are rearranged into the database structure.Methods: We selected random samples of 19,734 patients from approximately 1.6 million patients who received medical care between February 2018 and January 2019 in one of the 64 hospitals of the Tokushukai Medical Group. We excluded patients whose observation period was less than 365 days and identified 334 patients who met the definition of "possible cases of RA" whose medical charts were then independently evaluated by two rheumatologists. In a sensitivity analysis, we assessed bias due to misclassifying some patients with RA who did not meet the definition of "possible cases of RA" as a patient with no RA.Results: The kappa coefficient between the two rheumatologists was 0.80. The prevalence of RA in the study population was estimated to be 0.56%. We found that [condition code of RA] and ([any disease-modifying antirheumatic drug] or [oral corticosteroid with no systemic autoimmune diseases (other than RA) and no polymyalgia rheumatica]) had a relatively high sensitivity (approximately 73%) and a high positive predictive value (approximately 80%). In a sensitivity analysis, we found that when some patients with RA who did not meet the definition of "possible cases of RA" were misclassified as a patient with no RA, then this would lead to underestimation of the prevalence of the definition-positive patients and the adjusted prevalence.Conclusions: We recommend using the claims-based definition of RA (found in the current validation study) to estimate the prevalence of RA in Japan. We also suggest estimating the adjusted prevalence using the quantitative bias analysis method, since the prevalence of the disease in the "hospital-based" validation study is different from that in the administrative database.Trial Registration: The current study is not a clinical trial and hence not subject to trial registration. [ABSTRACT FROM AUTHOR]

Expressed emotion (EE) research has been productive in investigating the influence of the interpersonal environment on a range of disorders. The majority of EE research on the influence of carers has been carried out in the west. This is the first EE study of the carers of people with dementia in Japan. The aim of this study was to investigate the relationships between EE status and aspect of burden through cross-cultural comparison of the two countries, Japan and England, with large cultural and linguistic differences. Comparisons were made between samples of EE of carers of dementia and schizophrenic patients. In total, data on 80 carer/relative-patient dyads were collected and examined: (1) 20 Japanese carers of people with dementia (JD), (2) 20 English carers of patients with Alzheimer's disease (ED), (3) 20 Japanese relatives of patients with schizophrenia (JS), and (4) 20 English relatives of patients with schizophrenia (ES). The Camberwell Family Interview was administered in each country to ascertain levels of EE. Large differences between Japan and England were found in the frequency of critical comments, in which ES>ED>JS>JD. EE correlated significantly with burden in the JD sample alone. With an operational cut-off of 2CC (CC, critical comments), EE correlated significantly with cognitive impairment as well as with clinical severity in the JD sample. There was a tendency for lower expression of both positive and negative emotional reactions towards family members in the Japanese sample. The results of this study indicate that EE is an appropriate measure for use with carers of sufferers of dementia and can be utilized across different cultures. However, flexibility with the cut-offs may be required in Eastern cultures. This needs to be tested on larger samples with sensitivity to illness and cross-cultural differences.