The performance of the Japanese version of the K6 and K10 in the World Mental Health Survey Japan

Abstract

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.

Social Support Improves Mental Health among the Victims Relocated to Temporary Housing following the Great East Japan Earthquake and Tsunami

“…Therefore, we used this cutoff score of 13 as the definition of serious psychological distress. We used the Japanese version of the K6, which was developed through a standard back-translation procedure and has been validated (Furukawa et al 2008). The internal consistency reliability (Cronbach's alpha) for the K6 total score in our sample was 0.92.…”

Precarious Employment and Health: Analysis of the Comprehensive National Survey in Japan

“…The questionnaire included the Japanese version of the Kessler 6 (K6), a scale measuring psychological distress that is characterized by high internal consistency and reliability 22,23) . This instrument measures nonspecific psychological distress that is sensitive to discriminating DSM-IV cases from non-cases in the general population 24) .…”

Influences of income and employment on psychological distress and depression treatment in Japanese adults

“…The K6 consists of six questions that assess depressive mood and anxiety during the preceding 1 month, using answers on a 5-point scale ranging from ''none'' to ''very much'' [18,19]. The questionnaire on subjective complaints involved first asking ''Do you have any types of physical complaints?…”

“…Psychological distress was measured using the Japanese version of the K6 and psychological complaints. The K6 was scaled using six questions on a 5-point scale (none = 0 to very much = 4) [18,19]. The sum of six item scores (ranging from 0 to 24) was used to indicate the degree of depression and anxiety.…”