2019 年 90 巻 5 号 p. 473-483
The interpersonal-psychological theory of suicide proposes that suicide occurs in the presence of three factors: perceived burdensomeness, thwarted belongingness, and acquired capability for suicide. The Interpersonal Needs Questionnaire (INQ) was developed to assess the first two factors, and the Acquired Capability for Suicide Scale (ACSS) was developed for the third. Our study presented here developed and evaluated Japanese versions of the INQ and ACSS, and determined the best ones for Japanese samples. In Study 1, we asked 189 university undergraduates to evaluate each scale’s clarity. In Study 2, 812 undergraduates were asked about the INQ, the ACSS, and validity items, and 225 undergraduates participated in a second survey approximately one-month from the initial survey for test-retest reliability. In Study 3, 104 psychiatric patients completed the INQ and ACSS and were asked about suicidal ideation and suicidal attempt. Content, structural, generalizability, and external validity results showed that each version of the INQ and ACSS demonstrated acceptable validity. Our comprehensive evaluation provides evidence that INQ-10/INQ-15, and ACSS-5/ACSS-FAD can yield reliable data from Japanese-language population samples.