Assessment of acquired capability for suicide in clinical practice

The Interpersonal Psychological Theory of suicide proposes that the interaction between Thwarted Belongingness, Perceived Burdensomeness, and Acquired Capability for Suicide (ACS) predicts proximal risk of death by suicide. Instruments to assess all three constructs are available. However, research on the validity of one of them, the acquired capability for suicide scale (ACSS), has been limited, especially in terms of its clinical relevance. This study aimed to explore the utility of the different versions of the ACSS in clinical assessment. Three versions of the scale were investigated, the full 20-item version, a 7-item version and a single item version representing self-perceived capability for suicide. In a sample of patients recruited from a clinic specialising in the treatment of suicidality and in a community sample, all versions of the ACSS were found to show reasonable levels of reliability and to correlate as expected with reports of suicidal ideation, self-harm, and attempted suicide. The item assessing self-perceived acquired capacity for suicide showed highest correlations with all levels of suicidal behaviour. However, no version of the ACSS on its own showed a capacity to indicate suicide attempts in the combined sample. It is concluded that the versions of the scale have construct validity, but their clinical utility is limited. An assessment using a single item on self-perceived ACS outperforms the full and shortened versions of ACSS in clinical settings and can be recommended with caution for clinicians interested in assessing this characteristic.