Characteristics and Functions of Non-Suicidal Self-Injury That Inform Suicide Risk

Although non-suicidal self-injury (i.e., NSSI) has been suggested as a robust risk factor of suicide, NSSI related information that is most related to suicide risk remains unclear. Commonly studied NSSI characteristics are its frequency and the number of methods endorsed. However, it may not be merely how frequent or how many different methods that matters, but "why," which alludes to the importance of NSSI functions (or why individuals engage in NSSI). Thus, this study examined how the interactions between NSSI characteristics and functions are associated with suicide risk.

Undergraduate students (n = 820) with a lifetime history of NSSI, filled out self-report measures on NSSI and suicide risk. A hierarchical regression analysis was conducted to examine the moderation effects between four 2-way interactions (i.e., method X intrapersonal; method X interpersonal; frequency X intrapersonal; frequency X interpersonal) on suicide risk.

Main effects of all four independent variables were statistically significant. In terms of interactions, the intrapersonal function moderated both the effects of NSSI frequency and methods on suicide risk, whereas the interpersonal function moderated the effects of NSSI frequency on suicide risk.

Our results highlight that some NSSI related information than others are more indicative of suicide risk. In particular, the combination of NSSI functions, along with its frequency and number of methods, holds promise when assessing for current and lifetime suicidal thoughts and behaviors.