The association between nonsuicidal and suicidal self-injurious behaviors: A systematic review and expanded conceptual model.

Objectives: Nonsuicidal self-injury (NSSI) is one of the strongest predictors of suicidal behavior. Despite this, the field still has a limited understanding of the mechanisms by which this relationship is conferred.

Method: We conducted a systematic review of the empirical research examining potential factors driving (i.e., moderators, mediators) the relationship between NSSI and suicidal behavior to address this gap in the literature.

Results: We identified only 15 studies examining moderators or mediators of this relationship, examining 40 unique mediators and 22 unique moderators. Three prominent weaknesses were identified in the reviewed literature: (1) limited intersection with existing theoretical models of the NSSI - suicidal behavior relationship, (2) little replication of findings across studies (i.e., only four mediators and four moderators assessed in multiple studies), and (3) only one of the included studies utilized a prospective design. Research to date does little to improve our understanding of the theoretical or prospective relationship between NSSI and suicidal behavior, highlighting a foundational gap in the literature.

Discussion: We propose the Nonsuicidal to Suicidal Self-Injury Pathway Model, a new conceptual model of the relationship between NSSI and suicidal behavior, drawing on extant theory and empirical research; we discuss future directions for work in this area.