Functions of nonsuicidal self-injury: exploratory and confirmatory factor analyses in a large community sample of adolescents.

Abstract

Given that nonsuicidal self-injury (NSSI) is prevalent in adolescents, structured assessment is an essential tool to guide treatment interventions. The Functional Assessment of Self-Mutilation (FASM) is a self-report scale that assesses frequency, methods, and functions of NSSI. FASM was administered to 3,097 Swedish adolescents in a community sample. With the aim of examining the underlying factor structure of the functions of FASM in this sample, the adolescents with NSSI who completed all function items (n = 836) were randomly divided into 2 subsamples for cross-validation purposes. An exploratory factor analysis (EFA) was followed by a confirmatory factor analysis (CFA) using the mean and variance adjusted weighted least squares (WLSMV) estimator in the Mplus statistical modeling program. The results of the EFA suggested a 3-factor model (social influence, automatic functions, and nonconformist peer identification), which was supported by a good fit in the CFA. Factors differentiated between social/interpersonal and automatic/intrapersonal functions. Based on learning theory and the specific concepts of negative and positive reinforcement, the nonconformist peer identification factor was then split into 2 factors (peer identification and avoiding demands). The resulting 4-factor model showed an excellent fit. Dividing social functions into separate factors (social influence, peer identification, and avoiding demands) can be helpful in clinical practice, where the assessment of NSSI functions is an important tool with direct implications for treatment.