Early adolescence is the peak period of onset for non suicidal self-injury (NSSI)  providing, if detected, an opportunity for early intervention as the youth is at risk of developing a repetitive maladaptive coping strategy. In clinical practice, there are currently no routine standardized self report measures used to inform the understanding and treatment of NSSI despite its high prevalence rates in clinical populations [2, 3]. The majority of NSSI measures remain research tools. Having a measure of NSSI that is valid and clinically useful can inform case conceptualization and treatment planning.
While the clinical interview provides important information and the opportunity to develop a therapeutic alliance, many youth may not share the extent of their NSSI due to shame or difficulty expressing themselves fully in one on one questioning. Many find that self report measures are helpful to share information they would otherwise be reluctant to disclose . In addition, clinicians may not be able to provide as comprehensive questioning specific to NSSI nor necessarily have the time to do so in the first assessment interview. Many aspects of NSSI have been poorly understood in terms of its functions and other characteristics. The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5)  has included criteria for NSSI to the section “requiring further study” indicating that NSSI requires more research and proposing that NSSI does not solely exist as a symptom of borderline personality disorder.
Theories regarding the reasons or functions of NSSI have been postulated for several decades with an understanding that NSSI may serve more than one function . Klonsky  completed a comprehensive review of theoretical understandings of the functions of NSSI and research to date in the field. Seven main categories of functions of NSSI were derived from this review: affect regulation, self-punishment, antidissociation, interpersonal influence, interpersonal boundaries, sensation-seeking, and anti-suicide. The most commonly endorsed reason for NSSI is affect regulation with the intent to relieve negative affective states such as tension, depression, and/or anger. This category was the most highly endorsed function in a study of hospitalized adolescents where the mean number of endorsed reasons per individual, regardless of category of function, was approximately eight . In a paper entitled “Why do people hurt themselves?”, M. Nock provides an integrated theoretical model of the development and maintenance of NSSI. Distal risk factors such as genetic predisposition to high emotional/cognitive reactivity, intra and interpersonal vulnerability factors, responses to stress and specific NSSI vulnerability factors in the generation of NSSI are illustrated in how they may interact. This model helps to consider those at more risk for development of NSSI and incorporates the role and underpinnings of the potential functions of NSSI .
There remains some controversy regarding whether NSSI can become an addictive behaviour despite many youths self reporting this anecdotally and several studies providing evidence of addictive features. In a clinical study of youth with NSSI to study addictive features, Nixon Cloutier and Aggarwal , showed that 97.6 % of a clinical sample of 42 repetitive self injuring adolescents endorsed at least three dependence items on a seven-point criteria scale for addictive features of NSSI. This scale was adapted from the Diagnostic Statistical Manual of Mental Disorders IV TR (substance dependence criteria) . Schaub, Holly, Toste, and, Heath [personal communications, 2006], in a university sample of self-injurers, showed that 31 % endorsed at least three of the addictive features using the same seven-item scale. More recently, Moumne, Heath, Schaub, and Nixon [personal communications; 2014] found that of 137 out of 710 high school students surveyed that endorsed lifetime presence of NSSI, 20.4 % reported three or more Additive Features on the OSI addictive features scale. Those with addictive features had higher frequency, more methods and more locations of NSSI. Opposing the concept that NSSI has the potential as an addictive behaviour, Victor, Glenn, and Klonsky  found in comparing drug users and self injuring adolescents that cravings occurred primarily while experiencing negative emotions for NSSI with cravings of drug users being higher than that of self injurers.
In reviews of NSSI assessment tools [12, 13] there appears to be significant variability in functions that are measured between assessment tools. Despite the number of self-report measures assessing NSSI functions (e.g., Inventory of Statements About Self-Injury , Functional Assessment of Self-Mutilation ) none, except the OSI, assess potential addictive features in addition to functions of NSSI. The OSI is a self-report measure that offers a comprehensive assessment of NSSI, including both measurement of its functions and potential addictive features. The inventory was developed based on a comprehensive literature review, clinician feedback and input from adolescent psychiatric inpatients with NSSI. It contains a number of scales including an indication of frequency of recent NSSI thoughts and acts, reasons for starting and reasons for continuing to self injure (i.e., functions), addictive features, level of motivation to stop the behaviour and other characteristics of the nature of NSSI. Youth also respond to questions regarding what has or has not helped in terms of previous treatment (s).
The OSI has been previously validated in a community sample of self-injuring university students . Exploratory factor analyses revealed four function factors (Internal Emotion Regulation, Social Influence, External Emotion Regulation, and Sensation Seeking) and a single Addictive Features factor. Convergent evidence for the functions factors scores was demonstrated through significant correlations with the Functional Assessment of Self-Mutilation measure , a known tool for assessing the functions of NSSI. Convergent evidence was also noted for indications of psychological well being, risky behaviours, and context and frequency of NSSI. Convergent evidence for the Addictive Features scores was demonstrated through associations with NSSI frequency, feeling relieved following the act of NSSI, and the inability to resist urges to self injure. The conclusions of this preliminary research were that the OSI is a valid and reliable assessment tool that can be used in both research and clinical settings and that further research is warranted.
The purpose of this report is to describe a confirmatory factor analysis of the functions and addictive scales of the Ottawa Self-Injury Inventory (OSI) on youth hospitalized in a child and adolescent psychiatric inpatient unit in Ontario, Canada. These analyses were performed on data collected for a study on the characteristics of youth who accessed inpatient psychiatric care regarding nonsuicidal self-injury and suicidal behaviour . Comprehensive, accessible and user friendly measures such as the OSI fill a gap in the practice of assessment and offer clinicians a means to objectively assess the behaviour in a standardized fashion.