Evaluating the Psychometric Properties of the Interpersonal Needs Questionnaire and the Acquired Capability for Suicide Scale in Military Veterans

Joiner's (2005) interpersonal-psychological theory of suicide (IPTS) has become one of the most frequently studied in the field. Currently there are 2 primary measures designed to assess the 3 main constructs of the theory-the Interpersonal Needs Questionnaire (INQ; Van Orden, Witte, Gordon, Bender, & Joiner, 2008) and the Acquired Capability for Suicide Scale (ACSS; Van Orden et al., 2008). The psychometric properties of these 2 measures were evaluated in a sample of 477 U.S. military veterans. It was determined that the factor structure for both measures is consistent with the underlying theory and that all internal consistency reliability estimates are good. Acceptable convergent validity was found for the INQ, but not for the ACSS. Recommendations for refining the ACSS based on the results of the current analyses are provided. Comparisons of scale performance were made with data from participants with and without a history of 1 or more suicide attempts. Burdensomeness alone and the interaction between thwarted belongingness and burdensomeness were associated with prior suicide attempts. In conclusion, although some refinement may improve performance of the ACSS, both measures are appropriate and psychometrically sound for use in research and clinical applications with veterans of the U.S. military.