Capability for suicide is frequently assessed using the Acquired Capability for Suicide Scale (ACSS) or the Acquired Capability for Suicide Scale-Fearlessness About Death (ACSS-FAD); however, the measurement invariance of these self-report measures across relevant demographic groups has not been tested. The current study aimed to examine the measurement invariance of the ACSS and ACSS-FAD across (a) gender; (b) suicide attempt status; and (c) military deployment history in a sample of 2,551 participants (M = 28.92, SD = 10.73; 56.7% male, 68.5% White) who participated in one of several studies funded by the Military Suicide Research Consortium. Results indicated that the ACSS exhibited poor model fit; thus, further investigation of measurement invariance was not conducted. Furthermore, although partial measurement invariance of the ACSS-FAD was met for gender, scalar invariance was not supported across military deployment history, and no form of measurement invariance was met across suicide attempt status. Overall, given the lack of strong model fit and measurement invariance in the ACSS and ACSS-FAD across several demographic groups, new or modified self-report measures for capability for suicide may be warranted.
Public Significance StatementThis study examines the psychometric properties of the most commonly used measures for capability for suicide, the Acquired Capability for Suicide Scale (ACSS) and the Acquired Capability for Suicide Scale-Fearlessness About Death (ACSS-FAD). Results suggested that the ACSS was not suitable for assessing capability for suicide, and that the ACSS-FAD may be understood differently by different groups of people.