Two new screening scales for psychological distress, the K6 and K10, have been developed using the item response theory and shown to outperform existing screeners in English. We developed their Japanese versions using the standard back-translaton method and included them in the World Mental Health Survey Japan (WMH-J), which is a psychiatric epidemiologic study conducted in seven communities across Japan with 2436 participants. The WMH-J used the WMH Survey Initiative version of the Composite International Diagnostic Interview (CIDI) to assess the 30-day Diagnostic and Statistical Manual of Mental Disorders--Fourth Edition (DSM-IV). Performance of the two screening scales in detecting DSM-IV mood and anxiety disorders, as assessed by the areas under receiver operating characteristic curves (AUCs), was excellent, with values as high as 0.94 (95% confidence interval = 0.88 to 0.99) for K6 and 0.94 (0.88 to 0.995) for K10. Stratum-specific likelihood ratios (SSLRs), which express screening test characteristics and can be used to produce individual-level predicted probabilities of being a case from screening scale scores and pretest probabilities in other samples, were strikingly similar between the Japanese and the original versions. The Japanese versions of the K6 and K10 thus demonstrated screening performances essentially equivalent to those of the original English versions.

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The aim of the present study was to provide basic descriptive data regarding utilization of 12-month mental health services in the Japanese community population. Face-to-face household surveys were carried out in four areas (two urban cities and two rural municipalities), and a total of 1663 persons participated (overall response rate: 56.4%). For data collection, the structured psychiatric interview, World Mental Health version of the World Health Organization Composite International Diagnostic Interview (WMH-CIDI) was used, allowing DSM-IV diagnoses, severity, and service utilization. It was found that 7.3% of total respondents had received any service, either professional or non-professional, in the past 12 months, including 20.0% of those with 12-month DSM-IV disorders and 6.2% of those without. Thirty-three percent of those with any mood disorder used any service, and 26.8% of those used some type of health care. The probability of people with 13-15 years of education receiving mental health treatment was fourfold higher than those with ≥16 years of education. Gender, age, or income were not found to contribute to utilization of mental health services. The results confirm that the majority of people with a recent psychiatric disorder have not used mental health care or other support systems. The mental health care system in Japan has improved over the past decade, but not enough for people suffering from mental disturbances.